water efficiency in green building assessment tools

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Water Efficiency in Green

Building Assessment ToolsDissertation for the Masters of Science in Environmental Systems

Engineering

University College London07/09/2012

Ziad AwadSupervised by: Dr. Sara Bell


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AbstractThere are great challenges facing the construction industry; water resources are becoming scarce,

fossil fuel resources are running up, levels of air pollution in urban environments are rapidly

increasing and pressure is growing to achieve high levels of vital and green urban areas. In the

last years, a series of environmental assessment tools have been developed by commercial and

governmental research organizations, aiming at assessing the performance of buildings and

dwellings with regards to energy and water consumption, environment and ecology,

considering technology as well as social aspects of projects based on a life-cycle perspective.

The construction and operation of buildings are processes with substantial water footprints. This

study targets the water standards incorporated in three residential building assessment/rating

tools: the Leadership in Energy and Environmental Design for Homes (LEED for Homes) in the

United States, The Code for Sustainable Homes in the United Kingdom, and Green Star for

Multi-unit Residential in Australia. The research shows how these tools measure and prioritize

water efficiency with regards to the respective countrys water situation, and the extent to which

these measurement methods are able to account for behavioural as well as technical elements of

domestic water consumption, trade-offs between water, energy efficiency and carbon footprint,

and the need for regional flexibility to account for water resource availability. Based on internet

available information, literature reviews, data from environmental and governmental agencies, as

well as national statistics and past research reports, research showed that LEED for Homes and

the Code for Sustainable Homes do not account for regional environmental variations and water

availability throughout the country, in contrast with Green Star that sets different weighing

factors for each major Australian State and territory when addressing water and energy

efficiency. The study shows that it has nevertheless become necessary to adapt the rating tools

used in the U.S and UK according to the different regions water availability and carbon

footprint, especially since in these two countries, most areas with water availability tend to

witness high carbon emissions, and areas with water scarcity have low emissions. Moreover,

carbon emitting on-site rain water harvesting systems can be superfluous in regions rich with

water, and can be side stepped as requirements in green building rating tools, whereas they areessential in dry and arid regions.

Keywords: Water efficiency, energy efficiency, carbon emissions, green buildings, green

building rating tools, green building assessment tools, per capita consumption.


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AcknowledgementsI would like to gratefully and sincerely thank Dr Sarah Bell for her invaluable guidance and

patience throughout this project as well as her supportive assistance throughout the academic

year.

I would also like to thank DEFRA, the Environment Agency and the U.S Environmental

Protection Agency for providing helpful information as regards to this project.


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Tableof Contents

Abstract ......................................................................................................................................................... 1

Acknowledgements ....................................................................................................................................... 2

Chapter 1. Introduction and Scope ............................................................................................................... 7

1.1. What are green buildings? ............................................................................................................ 7

1.2. Scope of Study............................................................................................................................... 8

1.2.1. Aims and objectives .............................................................................................................. 9

1.3. Project plan and structure .......................................................................................................... 10

Chapter 2. Green Building Rating Tools and Water Efficiency .................................................................... 11

2.1. International rating tools ............................................................................................................ 11

2.4.1. History ................................................................................................................................. 12

2.2. Water efficiency and green buildings ......................................................................................... 13

2.2.1. The water-energy nexus in green buildings ........................................................................ 14

Water heating ................................................................................................................................. 16

Rainwater harvesting ...................................................................................................................... 17

Grey water recycling ....................................................................................................................... 17

Chapter 3. LEED for Homes ......................................................................................................................... 19

3.1. Overview ..................................................................................................................................... 193.2. The water situation in the U.S .................................................................................................... 20

3.3. Overview of the LEED for Homes water efficiency criteria ......................................................... 23

3.4. The need for regional flexibility of LEED for Homes ................................................................... 25

3.4.1. Synergies and trade-offs between water, energy and carbon footprint ............................ 26

3.5. Conclusions and recommendations ........................................................................................ 27

Chapter 4. The Code for Sustainable homes (U.K)...................................................................................... 28

4.1. Overview ..................................................................................................................................... 28

4.2. The water situation in the U.K .................................................................................................... 29

4.3. Overview of the Code for Sustainable Homes water criteria ..................................................... 30

4.4. The need for regional flexibility of the Code for Sustainable Homes ......................................... 32

4.4.1. Synergies and trade-offs between water, energy and carbon footprint ............................ 34


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4.5. Conclusions and recommendations ............................................................................................ 36

Chapter 5. Green Star for Multi-Unit Residential (Australia) ...................................................................... 38

5.1. Overview ..................................................................................................................................... 38

5.2. The water situation in Australia .................................................................................................. 41

5.2.1. Water shortages and drought ............................................................................................. 42

5.3. Overview of Green Star for Multi-Unit residential water criteria ............................................... 43

5.4. Water shortages resulting in increased awareness and water savings ...................................... 45

5.5. Conclusions and recommendations ............................................................................................ 47

Chapter 6. A Comparison of the Water Criteria in the three Green Building Assessment Tools ............... 48

Chapter 7. Conclusion and Recommendations ........................................................................................... 50

Bibliography ................................................................................................................................................ 53

Appendix 1 .................................................................................................................................................. 57

Appendix 2 .................................................................................................................................................. 58


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List of Figures

Figure 1: Rating Systems in the world (from Reed et. al, 2009) .................................................. 11

Figure 2: Timeline of the Development of Rating Tools in Different Countries (Reed et al. 2009)

....................................................................................................................................................... 12

Figure 3: CO2 emissions associated with water abstraction, treatment, conveyance, use and

disposal (from Clark et al., 2009). ................................................................................................ 15

Figure 4: CO2 emissions from domestic water use in a home with gas heating (from

Environment Agency, 2009) ......................................................................................................... 16

Figure 5: Indoor water use in the U.S (from EPA, 2009) ............................................................. 20

Figure 6: Per capita water consumption and expected population growth throughout the U.S

(from EPA, 2009).......................................................................................................................... 21

Figure 7: Precipitation in the U.S (from EPA, 2009) ................................................................... 22

Figure 8: Pathway through water efficiency (from LEED for Homes, 2008) .............................. 23

Figure 9: Areas of predicted relative water stress (from NRDC, 2010) ....................................... 25

Figure 10: Per capita carbon emissions in the U.S (from Mongabay, 2008) ................................ 26

Figure 11: UK domestic Water use (from Waterwise, 2010). ...................................................... 29

Figure 12: EU countries per capita water consumption (litres/person/day) (from Waterwise,

2006)............................................................................................................................................. 31

Figure 13: UK per capita water consumption (from Environment Agency, 2008) ..................... 32

Figure 14: Water availability in the UK (from DEFRA, 2008) .................................................... 33

Figure 15: Per capita carbon emissions in the U.K (from the Department of Energy and Climate

Change, 2007)............................................................................................................................... 35

Figure 16: Areas of relative water stress in the UK (from Environment Agency, 2007) ............ 35

Figure 17: Areas of average domestic usage (Riverina Water, 2012).......................................... 41

Figure 18: change in amount of rainwater tank installed (from ABS, 2010) ............................... 45

Figure 19: change in the amount of houses with water saving products (from ABS, 2010) ........ 45
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List of Tables

Table 1: Points required to achieve each level of the LEED for Homes rating system ................ 19Table 2: Summary of water efficiency requirements in LEED for Homes .................................. 23

Table 3: : Minimum water requirements for each code level (from The Code for Sustainable

Homes, 2007) ............................................................................................................................... 30

Table 4: Points awarded for different water standards (from the Code for Sustainable Homes,

2007)............................................................................................................................................. 30

Table 5: Minimum water and energy requirements to achieve each level of the Code (from the

Code for Sustainable Homes, 2007) ............................................................................................. 34

Table 6: Points required to achieve each level of Green Star ....................................................... 39

Table 7: Green star for Multi-Unit residential water criteria (adapted from Green Star Multi-Unit

residential rating tool) ................................................................................................................... 43

Table 8: Comparative table of the three building rating tools ...................................................... 48


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Chapter 1. Introduction and Scope

The Brundtland report, published by the World Commission on Environment and Development,defines sustainable development as development that meets the needs of the present without

compromising the ability of future generations to meet their own needs. Paradoxically, the

world today is witnessing significant depletion of resources that will imminently be felt by future

generations (Kothari, 2010). Buildings construction and operations currently account for

approximately 45-50% of the worlds energy consumption (WilmottDixon, 2010), 43% of all

emitted carbon dioxide (Kelly, 2008), and 20% of the worlds available water (United Nations

Environmental Programme, 2008) with a higher share in developed economies. As with the

expected growth of the worlds population and modernization of infrastructures, the built

environment will only expand further into the natural environment, and green efficient buildings

are becoming increasingly crucial to cutting resource consumption and achieving a sustainable

development. While there are different types of green structures (office, industrial, education )

targeting the efficiency of all natural resources, this particular study aims at evaluating the water

situation and domestic water consumption in the USA, UK and Australia, as well as the water

criteria in the three green residential building assessment tools used in these countries: LEED for

Homes, The Code for Sustainable Homes, and Green Star for Multi-unit Residential.

1.1. What are green buildings?There are major challenges facing the construction industry; fossil fuel resources are running up,

levels of air pollution in urban environments and drinking water resources are very scarce. These

challenges imply that our built environments need to evolve to meet the increasing demand on

land-use and natural resources, while simultaneously reducing their contribution to greenhouse

gas emissions and resource consumption, along with improving environmentally safety,

economically productive and socially inclusive environments. According to the green building

index organization (2011), a green building focuses on increasing the efficiency of resource use

energy, water, and materials while reducing building impact on human health and the

environment during the buildingslifecycle.


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Green or sustainable buildings are structures using environmentally friendly and resource

efficient processes throughout their life-cycle: from siting to design, construction, operation,

maintenance, renovation, and demolition. They are intended to use energy, water and other

natural resources much more efficiently when compared to conventional buildings, as well as

minimize pollution, waste and any negative environmental impacts, while assuring occupants

comfort , safety and well-being. There are minimum requirements that a building must meet in

order to be given the green status. These requirements were set by green building councils

worldwide, creating as a result green building assessment/rating tools that will be discussed in

more detail in the following chapter.

1.2. Scope of StudyBuilding sustainability assessment tools, also known as green building assessment tools or rating

tools, differ in how they measure and prioritize water efficiency. This project will review three

methods for addressing water efficiency in green dwellings: LEED for Homes in the US, The

Code for Sustainable Homes in the UK (hereafter referred to as the Code or CSH), and Green

Star for Multi-unit residential in Australia, which are the most recent design assessment tools

developed in each country.These particular schemes have been selected because CSH and LEED

have been introduced by very well-known world leading organisations (BRE and USGBC) that

have a proven record in the domain of sustainability development, and because Green Star was

practically entirely built on both the BREEAM and the LEED rating systems. In addition, the

three systems are related to three major developed countries with different environmental

conditions and geographical locations.

The study will evaluate the extent to which these measurement methods are able to account for

behavioural as well as technical elements of domestic water consumption, trade-offs between

water and energy efficiency, and the need for regional flexibility to account for water resource

availability. Although each country adapts its own rating tool conforming to their relative

environment, Green star is the only one that accounts for regional environmental variations

within the country. Following an overview of the concerned countrys water situation, the study

will evaluate the water criteria in the three rating tools mentioned, followed by an assessment of

the rapport between water and carbon emissions, and the need for regional flexibility of the


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assessment method within each country. A comparison of the water efficiency requirements of

the three rating tools will be conducted, which will show differences and consistencies between

them. Based on the analysis of each rating tools, recommendations to improve the applicability

of each tool will be stated. The findings, data, and information compiled in this document were

collected through internet available information, literature reviews, environmental and

governmental agencies, as well as national statistics and past research reports.

1.2.1. Aims and objectivesThe aim of this study is to show to which extent is the water criteria in the three studied green

building rating tools well suited for their specific countrys climate and water conditions, and

what can be done to improve their applicability.

The objectives of the project are as follows:

Describe the areas in which energy and water consumption are interdependent in adomestic building.

Clearly illustrate and describe each assessment tool and their relative water standards. Quantitatively and qualitatively assess the countrys water situation. Establish a link between the countrys water situation, the water efficiency standards of

the building assessment tool used in that country and the need for its regional flexibility. Compare the three rating tools and locate differences and consistencies. Create a preliminary set of recommendations for each rating tool that can help improve

their application in each country.


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1.3. Project plan and structureTo complete the studys objectives, this report was divided into 7 chapters. The following

chapter will give an overview of the green building rating tools currently being used in the

world, as well as explain the goals and components of water efficiency in green buildings, and

the energy and carbon footprint related to water efficiency methods specified in green building

assessment tools. Chapter 3, 4 and 5 will illustrate and evaluate the water criteria in the three

green building tools concerned in this study: LEED for Homes, The Code for Sustainable

Homes, and Green-Star for Multi-Unit residential. The individual analysis will comprise an

overview of the tools water criteria, and the extent to which they are flexible within the country.

Consequently, a comparison of the three rating tools will be done in chapter 6, summarizing the

main findings in each part of the individual analysis. The last chapter will consist of a

conclusion, outlining the main findings of the study, and discussing further research topics and

recommendations for future development of each rating tool.


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Chapter 2. Green Building Rating Tools and

Water Efficiency

2.1. International rating toolsIn order to classify a building as green, rating tools have been created containing a set of criteria

that green buildings have to abide by. These sustainability assessment tools award credits for

building features that support green and sustainable design, in categories such as location and

maintenance of building site, waste and pollution prevention, conservation of building materials,

energy and water efficiency, and occupant comfort and health. The number of credits typically

determines the level of achievement i.e. the higher the level achieved, the greener the building.

While it is acknowledged that there are no identical parcels of land in the world (Australian

Property Institute, 2007), the World Green Building Council concedes that one tool cannot fit all

countries, with each country having different climate and environmental conditions, notably

when it comes to water resources and availability. Green building councils for each country have

implemented country specific rating tools as shown in the figure below:

Figure 1: Rating Systems in the world (from Reed et. al, 2009)


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2.4.1.HistoryBuilding assessment/rating tools were primarily developed to evaluate specific aspects of a

building pertaining to sustainability goals (McKay, 2007). They were meant to address key waste

issues and inefficiencies in buildings, mainly focusing on three main areas; energy, water and

material use in buildings (World Green Building Council, 2007).

To develop green building assessment tools, authors used existing sustainable practices, such as

increased day lighting, operable windows, improved efficiencies in energy and water use, and

promoted biodiversity, material reuse, recycling, and urban infill or densification (McKay,

2007). The varying backgrounds and opinions of authors helped in providing a holistic approach

to building design. The content of the tools was also influenced by political and corporate

interest (incentives or interested directions), and environmental trends (recycling, oil crises)

(Elisa Campbell Consulting, 2006).

The tools aimed at providing a process that will allow the comparison of different building traits,

and provide in the end a numerical value to compare with other assessed buildings. The

birthplace of environmental assessment tools is considered by many to be UKs BREEAM

(British Research Establishments Environmental Assessment Method), which is the first

assessment tool ever drafted for green buildings in 1990. Many of todays tools are based upon

or were influenced by BREEAM (McKay, 2007). Once BREEAM was created, other assessmenttools in different countries succeeded as shown below:

Figure 2: Timeline of the Development of Rating Tools in Different Countries (Reed et al. 2009)


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Since 1998, national council representatives have met to review global activities and offer

support for each other's efforts. Formal incorporation of the World Green Building Council took

place in 2002, aiming to formalize international communications, help industry leaders access

emerging markets, and provide an international voice for green building initiatives (World

Green Building Council, 2007).

A list of most of the worlds green building rating tools can be found in Appendix 1. LEED,

BREEAM and Green Star are three of the most common rating tools used in the world (Reed et

al, 2009), and initiated in three countries with significant differences in climate and

environmental conditions. It has been reported that BREEAM, LEED, and Green Star, are

seeking to develop common metrics that will help international stakeholders compare buildings

in different cities using an international language (Kennett, 2009). In addition, most of the

rating tools created in the world can be traced back to these three tools (Reed et al, 2009). As

only green residential houses and buildings will be studied in this project, the concerned rating

tools for this project are LEED for Homes (by USGBC), The Code for Sustainable Homes (by

the Communities and Local Government, UK), and Green Star for Multi-unit residential (by

GBCA) .

2.2. Water efficiency and green buildingsIn 1999, the United Nations Environment Programme (UNEP) reported that scientists in50

different countries had identified water shortage as one of the two mosttroubling problems for

the new millennium, with the other being global warming. There are several reasons for water

shortages, one being the simple rise in population, and the desire for better living standards.

Another is the inefficiency of the way we use much of our water (Kirby, 2000). The issue in

water consumption is that in many regions, the demands on the supplying aquifer exceed its

ability to replenish itself. To compensate, facilities can increase their dependence on water that

is collected, used, purified, and reused on-site, to the maximum extent feasible. Water

conservation efforts can play a major role on sustainability by assuring that the rate of water

replacement in the ecosystem is greater than that of which the water is being abstracted,

consequently leading to water preservation.


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Protecting water quality and reducing water consumption are essential elements in sustainable

green buildings. Water efficiency measures in buildings are based on three criteria: Rainwater

harvesting, water recycling and water-saving fittings. The protection, management and

conservation of water throughout the life of a building may be achieved through several methods

such as installing dual plumbing that recycles flushed water in toilets and utilizing water

preserving fixtures such as low flush toilets and low-flow shower heads to minimise waste water.

Besides, point of use water treatment and heating can improve both water quality and energy

efficiency while reducing the amount of water in circulation, and the use of harvested rain water

and recycled greywater for indoor use as well as on-site use such as site-irrigation can minimize

demands on the local aquifer. Green building rating tools award credits for such applications

leading to water savings. Further details will be discussed in the individual rating tools chapters.

Nonetheless, it is important to point out that the value and cost-effectiveness of a water

efficiency measuremust be evaluated in relation to its effects on the use and cost of other natural

resources and environmental implications such as energy use and carbon footprint. This can be

done based on the environmental nature of a specific region. For instance, in humid and water

profuse climates, where the aquifer is capable of quickly replenishing itself, it is necessary to

evaluate whether it is more viable to install on-site water recycling systems for homes which can

have weighty carbon footprints, or acquire water from local supply systems. To do so, numerical

benchmarks must be set for a specific region to evaluate whether or not the water savings from

on-site harvesting and recycling systems would compensate for their energy and carbon

footprint.

2.2.1.The water-energy nexus in green buildingsWater and energy in buildings are intertwined, not only at the point of consumption, but at the

point of generation as well. Providing households with safe drinking water and wastewater

disposal is an energy-intensive process (US Army Corps of Engineers, 2006). Reducing water

consumption saves energy since less water needs to be treated and pumped to end users. The

main energy consuming and CO2emitting activities related to water in a home and regulated in

building assessment tools are concerned with heating water, treating greywater and harvesting

rainwater. It is important to evaluate how water efficiency can affect energy consumption and


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carbon emissions, in order to state whether greywater recycling and rainwater harvesting can be

sidestepped when constructing a green building, in regions where water is abundant. Given that

buildings using harvested rainwater or treated greywater typically increase greenhouse gas

emissions compared to using mains water (Parkes et al., 2010), it has become necessary to weigh

the advantages, depending on the climate of the corresponding region, of harvesting rainwater

and treating greywater against using mains water in homes. Figure 3 illustrates the carbon

emissions that result from a typical home:

Figure 3: CO2 emissions associated with water abstraction, treatment, conveyance, use and disposal (from Clark et al., 2009).

As shown in Figure 3, most CO2emissions associated with the supply-use-treatment cycle of

water related to the domestic sector are during the use phase of water with 89% of emissions

attributable to water use in the home and the remaining 11% attributable to utility companies.

The emissions from water use in households result mostly from water heating (Clark et al.,

2009). Adding on-site water recycling and harvesting systems can increase net CO2 emissions in

households. The next sections are based on three studies conducted by the Environment Agency

in conjunction with the Energy Trust, and will briefly outline the relationship between water

efficiency, energy efficiency and carbon footprint in three systems applied in residential

dwellings.


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Water heating

Figure 4: CO2 emissions from domestic water use in a home with gas heating (from Environment Agency, 2009)

The major CO2 emissions from heating water in homes are related to the volume of hot water

used. Hot water use in new houses is higher in volume than in the existing housing stock, mainly

because of increased ownership of showers, higher flow rates and more frequent use (Clarkes et

al., 2009). According to the above graph, the CO2 emissions from water use in new houses

almost equates to those in existing houses, despite increases in boiler efficiency and decreases in

water use for flushing toilets in new homes. For that reason, water efficient fittings stated in

building assessment tools might not be as effective when it comes to carbon footprint of water

heating, if the amount of water used by the occupants is increasing. Although water efficient

fittings will help occupants to reduce the amount of water needed for certain tasks, occupants

awareness is necessary in order to decrease the use of hot water and hence the amount of carbon

emissions resulting from heating water. Figure 4 clearly illustrates this fact by showing that a

home built to code level 6 (highest level that can be achieved by the Code for Sustainable

Homes) almost results in the same amount of carbon emissions from a regular dwelling

(delivered hot water bar in dark blue).


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Rainwater harvesting

Rainwater harvesting systems use electricity to run pumps and control systems. This operational

energy use, mainly for pumping, contributes a significant proportion of the carbon footprint of a

system, with the remainder as embodied carbon in system materials, and arising from transport

for system delivery and maintenance (Parkes et.al, 2010). The Environment agency reported

after monitoring multiple systems that the energy intensity of a rainwater system is higher than

mains waters. Pumping water from the rainwater tank to end uses gave rise to higher carbon

emissions than those arising from the supply of mains water to buildings.

The main factors determining the carbon footprint of a rainwater system are the type of tank

used, the pumping arrangement and the amount of rainfall, given that increased rainfall results in

higher carbon emissions from the system because more water is dealt with and pumped.

Grey water recycling

Different types of greywater systems, their scale and their different treatment levels make them

suitable to specific applications. Low level treatment systems, such as, short retention systems

are applicable to homes (Parkes et al., 2010). Short retention systems involve a very basic

treatment. A proportion of the wastewater drained from the bath or shower is collected and

stored. The storage vessels include simple treatment techniques such as particle settlement and

surface skimming to treat the water. These storage vessels provide a supply of greywater fortoilet flushing only. Systems are normally located in the same room as the source of greywater

(or within close proximity), reducing the need for building wide dual-network plumbing. Short

retention systems have negative net operation carbon emissions. The energy intensity required

for such systems is found to be below the median intensity required by mains water (intensity

being variable depending on many environmental factors). All other systems were found to have

higher emissions than of the mains.

Greywater recycling has a main advantage over rainwater recycling in that the water does not

depend on rainfall and is more consistently available for use.


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The Environment Agency asserts in these studies that water efficient fittings, grey water

recycling and rain water harvesting systems do in fact result in water savings. The issue remains

however in whether these savings actually compensate for the amount of carbon they emit in

certain regions, especially in areas where water is plentiful.

The previous findings can be summed up as follows:

i. Carbon emissions from heating water are highly due to the amount of water used,rather than the fittings and appliances used.

ii. Rain water harvesting systems typically have higher carbon footprints than mainssystems.

iii. The main factors determining the carbon footprint of a rainwater system are the typeof tank used and the pumping arrangement.

iv. Higher rainfall increases rainwater savings, and hence carbon footprint. Emissionsassociated with rainwater systems vary with rainfall, which depends strongly on

regional location.

v. Short retention systems for greywater are the only types of systems that have lowercarbon footprints than mains systems. They are perfectly suitable for homes.

Further research should be conducted regarding the effectiveness and efficiency of a central rain

water harvesting system that can service multiple homes in a certain region, which can eliminate

the need for installing a system for individual households.


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Chapter 3. LEED for Homes

3.1. OverviewDeveloped by the U.S. Green Building Council (USGBC) in 1998, the Leadership in Energy and

Environmental Design (LEED) is a rating system that targets the design, construction and

operation of high performance green buildings, homes and neighbourhoods (USGBC, 2003). It is

a building certification that provides third-party confirmation that a building, home or

community was designed and built using approaches intended to achieve high performance in

five key areas of human and environmental well-being: sustainable site development, water

efficiency, energy efficiency, materials selection and indoor environmental quality.

LEED for Homes, a part of the comprehensive suite of LEED assessment tools offered by

USGBC, is a voluntary rating system promoting the design and construction of high-

performance green homes. The LEED for Homes Rating System launched in 2008, measures the

overall performance of a home in eight categories:

Innovation & Design Location & Linkages Sustainable Sites Water Efficiency

Energy & Atmosphere Materials & Resources Indoor Environmental Quality Awareness & Education

This study is concerned with the LEED for Homes rating system v.2008, applicable only to

buildings with fewer than 4 above-grade stories. The rating System works by requiring a

minimum level of performance through prerequisites in certain categories, and rewarding

superior performance in each of the above categories. The level of performance is indicated by

four performance levels; Certified, Silver, Gold and Platinum as shown in the table below:

LEED for Homes certification level Number points Required

Certified 45-59

Silver 60-74

Gold 75-89

Platinum 90-136

Total points avail able 136Table 1: Points required to achieve each level of the LEED for Homes rating system


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3.2. The water situation in the U.SThe U.S has abundant water resources which comprise approximately 400 cubic miles

1of

annually renewable stream flow. 113 cubic miles of water is abstracted annually to support

industrial, agricultural and domestic uses (NRDC, 2009). However, water resources and

consumption levels are not evenly distributed across the country and their availability varies by

season. There are several hot spot areas in the U.S. where a combination of water scarcity,

increased consumption and population growth are likely to lead to problems in balancing

demand and supply (US Army Corps of Engineers, 2006).

Homes use more than half of publicly supplied water in the United States, significantly

exceeding the amount used by either business or industry (Watersense, 2009). The quantities

used can increase depending on location; for instance, the arid west has some of the highest percapita residential water use because of landscape irrigation. The United States Geological Survey

estimated that 29.4 billion US gallons (111,000,000 m3) per day in 2005 were allocated for

domestic water use in the United States, which is mainly provided by public networks. The

average domestic water use per person in the U.S. is 370 Litres/person/ day, which equates to

about 2.5 times the figure in the U.K (150 Litres/person/day). The per capita domestic water use

varies from 51 US gallons (190 Litres) per day in Maine to 189-US-gallon (720 Litres) per day

in Nevada (United States Geological Survey, 2005), with a high share for outdoor use. Typically

all over the U.S, 58% of domestic water is used outdoors for gardening, swimming pools etc. and

42% is used indoors such as:

Figure 5: Indoor water use in the U.S (from EPA, 2009)

1The US measurement units are used in this chapter since they are the ones adapted by LEED.


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In aggregate, the current situation with water demand, supply and distribution in the U.S. appears

to be manageable. In the future however, the number of hot spots is likely to increase in response

to several trends and uncertainties such as population and economic growth, aging water supply

infrastructure, climate change which will affect both local and regional balances of supply and

demand (US Army Corps of Engineers, 2006).

The increase in water use in the United States in the past five years has caused for nearly every

region of the country to experience water shortages. At least 36 states are anticipating local,

regional, or state wide water shortages by 2013, even under non-drought conditions (NRDC,

2009). Several states, particularly those in the Southwest, such as New Mexico, California,

Nevada and Texas, are already struggling with shortages and the south is experiencing droughts

at "exceptional" levels. The combination of little rain and searing heat drains reservoirs and

increases water consumption, and there's simply not enough to go around (Gordy, 2012).

The diversified domestic water consumption and amount of rainfall throughout the country can

be illustrated in the following figures:

Figure 6: Per capita water consumption and expected population growth throughout the U.S (from EPA, 2009)


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Figure 7: Precipitation in the U.S (from EPA, 2009)

The Environmental Protection Agency projects that the population growth will be higher in the

western regions of the country than in the eastern regions. In addition, the west consumes much

more water than the east (Figure 6), even though it witnesses much less rainfall during the year

(Figure 7). This combined with the population growth and high water consumption can present a

serious challenge to water availability and supply in the future in the western regions of the

country (Figure 9 shows predicted levels of water stress in 2050) , and a necessity in better

regulating the water consumption and footprint of the domestic sector is apparent.


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3.3. Overview of the LEED for Homes water efficiency criteriaA minimum of 3 points must be achieved in the Water Efficiency category in order for it to be

considered in the overall score. It comprises three issues:

Figure 8: Pathway through water efficiency (from LEED for Homes, 2008)

The following table summarizes the water efficiency standards stated in LEED for Homes:

WaterReuse

Rainwater harvesting system (Max. 4 points)

And/orGraywater reuse system (water collected from sources exceeding 5000

gallons/year) (1 point)

ORUse of municipal recycled water system (Applicable only in communities with a

municipal recycled water programme) (3 points)

Irrigation

System

High efficiency irrigation system (Max.3 points)And/or

Third-party inspection (1 point)

OR

Reduce overall irrigation demand by at least 45% (Max. 4 points, depending on

reduction amount)

IndoorWater Use

High-efficiency fixtures and fittings (1 point for each fitting and/or fixture, max. 3

points)

OR

Very high efficiency fixtures and fittings (2 points for each fitting and/or fixture,max. 6 points)

Table 2: Summary of water efficiency requirements in LEED for Homes


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Unlike the other categories, there are no pre-requisites instated for the water efficiency category

in LEED for Homes, which makes this category more or less voluntary, and can be compensated

by points from other categories.

The amount of certified homes is growing in an encouraging rate. According to a recent study by

McGraw-Hill Construction, more than 20,000 U.S. homes have achieved certification through

LEED for Homes since the programs launch in 2008, with nearly four times that number

currently registered and working toward certification. Green building is expected to account for

about one-third of the residential market by 2016. However, as previously stated, homes can be

certified without satisfying any of the water efficiency requirements.


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3.4. The need for regional flexibility of LEED for HomesThe United States is facing serious threats regarding water availability and supply in the near

future, especially in the western and southern regions where in some states the situation will

become exceptionally severe, as shown in the figure below:

Figure 9: Areasof predicted relative water stress (from NRDC, 2010)

If climate warming continues to increase, it is expected that the risks of water shortages will

increase with it (NRDC, 2009). The Environmental Protection Agency and the NaturalResources Defence Council predict that in the coming decades, climate change will have major

impacts on water supplies throughout the country, with over 1,100 counties facing greater risks

of water shortages due to the effects of climate change and population growth (Watersense,

2009). It is necessary to adjust the requirements in LEED for Homes in order for the system to be

more adaptive to local environmental conditions. While receiving praise for its thoroughness and

merchantable cachet, most of the LEED for Homes criticism revolves around its scoring system

and the fact that it does not adapt to local environmental circumstances. Peter Pfeiffer, principal

of Barley & Pfeiffer Architects states in an interview with Residential Architect magazine, thatthe points in this LEED system do not necessarily relate to what's effective in a specific climate.

He gives an example that a point for graywater reuse and a point for rainwater harvesting is

awarded, when rainwater harvesting and greywater recycling can provide 10 times the amount of

water per dollar spent in the state of Texas (Weber, 2007).


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3.4.1.Synergies and trade-offs between water, energy and carbonfootprint

Energy-related CO2emissions account for the majority of greenhouse gas emissions in the U.S.

The following figure illustrates the per capita carbon emissions in the U.S:

Figure 10: Per capita carbon emissions in the U.S (from Mongabay, 2008)

Figure 10 clearly shows that the highest per capita carbon emissions are resulting from the

eastern parts of the country. On the other hand, figures 7, 8 and 9 show that water related stressesexist mostly in the western parts of the U.S. Evidently, water stresses exist in the parts of the

country with relatively low carbon emissions (with the exception of the states of Florida in the

south east and Oklahoma in the mid-south where both problems seem to persist).

In addition, despite the carbon footprint of rainwater harvesting and grey water recycling, these

on-site systems seem to be essential in the western and south-western regions of the country, in

order to reduce pressure on local water resources as much as possible, as stated previously by

architect Peter Pfeiffer. The types of systems however need to be taken in consideration, bearing

in mind that they play an important role in the amount of emitted carbon. The U.S Environmental

Protection Agency and other committees recognize greywater recycling and rain water

harvesting as good options for dry and arid regions, where the temperature can spike and there is

the possibility of long periods without rain. This allows for the reuse of water and an effort for

conservation (Watersense, 2009).


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3.5. Conclusions and recommendationsLEED for homes encompasses all the categories impacting the environment. It dictates some

mandatory requirements for certain categories, however none for water efficiency. Studies show

that the United States will imminently face water shortages, particularly in the western and

southern regions of the country. In these regions, severe water related problems are very likely to

occur soon, whereas in the eastern parts, although water does not constitute much of a problem,

high per capita carbon emissions are witnessed, which are likely to increase with population

growth (Stanton et al., 2010).

The following recommendations could improve the applicability of LEED for homes in the U.S:

A first step can be done to adjust LEED for Homes, by creating 2 versions: one to beused in regions of the west and south-west (with emphasis on water efficiency) and the

other for the east and northeast (with emphasis on energy efficiency and carbon

emissions).

Similarly to LEED New Construction, LEED for Homes can award credits for regionalflexibility, and adjust requirements to individual states, through a collaboration of the

USGBC with local state governing organisations and agencies.

A weighing factor could be assigned to each state depending on climate, and can bemultiplied by the actual categorys score (as done by Green Star shown in chapter 5)

Include rain water harvesting and/or grey water recycling as mandatory requirements orprerequisites in states of the west and the south-west.


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Chapter 4. The Code for Sustainable

homes (U.K)

4.1. OverviewThe UK based Building Research Establishment (BRE) launched in 1990 the BRE

Environmental Assessment Method (BREEAM), a sustainability measuring tool and rating

system for new non-domestic buildings in the UK. BREEAM targets performance measures

related to energy and water use, the internal environment (health and well-being), pollution,

transport, materials, waste, ecology and management processes. Since its inception, BREEAM

has evolved in scope and has grown geographically, being exported in various guises across the

world. A domestic version of BREEAM was established in 2000 under the scheme EcoHomes

which was replaced by its successor the Code for Sustainable Homes in April 2007, with

collaboration with the Department of Communities and local Government.

While BREEAM is the foundation of all UK green building assessment tools, this study is only

concerned with ones targeting residential homes and buildings, which in the U.K, is the Code for

Sustainable Homes, an environmental assessment government-owned scheme and national

standard for rating and certifying the environmental performance of newly built dwellings in

England and Wales. The code measures the overall performance of newly built dwellings in 9

categories:

Energy and CO2Emissions Water Materials Surface Water Run-off Waste

Pollution Health and Well-Being Management Ecology

A home can achieve a sustainability rating from one () to six () stars depending

on the extent to which it has achieved Code standards, with one star () being the entry level

and six stars () the highest level. Credits are awarded for meeting the criteria of

each category and the total credit score is translated to an overall percentage that dictates the

level rating (from 1 to 6). The current requirement for publicly funded housing in England and

Wales is to attain level 3 of the Code for Sustainable Homes.


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4.2. The water situation in the U.KThere are four main uses of water in the UK: Domestic (public water supply), power generation,

industrial and agricultural. Household water demand has been increasing since the 1950s, due to

population growth and changes in the way water is used at home, and is now more than half of

all public water supplied (DEFRA, 2008).Reduced domestic demand through more efficient use

of water in the home would reduce the extent of abstraction needed for public supply, and help

alleviate new and existing pressures on water resources. The water availability status in England

and Wales varies from one region to another. In the southern and eastern regions of England,

rainfall is relatively low, yet per capita water consumption tends to be higher than elsewhere and

abstraction is above its sustainable level in some areas (Figure 13 and 14). Combined with

projections for rainfall and demand, this has led to the classification of all south-eastern areas as

seriously water stressed (DEFRA, 2008).

The current governmental water consumption target per capita stated by DEFRA in their report

Future Wateris 130 Litres/person/day by 2020. The average per capita domestic water use in the

UK, as well as in England and Wales today is 150 Litres/person/day (Water UK, 2008). Over the

past decade, there has been little change in the average amount of water each person uses at

home in England and Wales (Environment

Agency, 2008). The Total water supplied in

England and Wales is 16.5 billion litres/day,

of which approximately 9 billion litres/day

for domestic use (Water UK, 2008)

distributes as shown in Figure 11. The

Environment Agency predicts that if no

action is taken to increase water efficiency,

the per capita consumption will remain at

150 Litres/person/day by 2020. The most

effective action in order to reduce the per

capita consumption is to increase the amount of water efficient dwellings. A brief simulation is

conducted in the following section showing the optimal number of houses that need to be

certified, including the amount that needs retrofits, given that most households that will be in use

in 2020 have already been built.

Figure 11: UK domestic Water use (from Waterwise, 2010).


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4.3. Overview of the Code for Sustainable Homes water criteriaWithin the Code are challenging water use requirements that necessitate the installation of very

low flow taps and showers and may also need non-potable water supplies from collected

rainwater or wastewater from baths and showers. The tables below show the minimum standards

and number of points awarded for achieving each of the per capita water consumption targets:

Table 3: : Minimum water requirements for each code level (from The Code for Sustainable Homes, 2007)

Table 4: Points awarded for different water standards (from the Code for Sustainable Homes, 2007) Reduction in potable water consumption can be achieved by e.g. using flow restrictors, low flush

toilets, and by collecting and recycling rainwater. 1.5 points can be acquired by using rainwater

for irrigation. The Code gives more flexibility to the owner than LEED for Homes in terms of

what measures can be taken, as long as the per capita water consumption requirement for a

specific level is met.


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Because The Code for Sustainable Homes states per capita requirements for water consumption

in a dwelling, a brief simulation was conducted using Microsoft Excel Solver, to calculate the

optimal housing stock that needs to be certified in order to reach the 130 litres/person/day water

target by 2020. The calculations and input data used in the programme, based on data provided

by the UK national statistics, are shown in Appendix 2. The simulation involved only two

different scenarios; the first included houses built to level 3, and the other included houses built

to level 3 and 6. The calculations lead to the following results:

At least 8 million dwellings must achieve level 3 of the code in order to reduce the percapita water consumption to 130 Litres/person/day, which equates to approximately 31%

of the projected housing stock in England and Wales in 2020, comprising approximately

26 million houses (UK national statistics, 2010). This means that approximately 6 million

houses already built will need to be retrofitted for efficient water use.

In the second proposed scenario, the best way of action is to retrofit 5.5 million houses tomeet the codes level 3 requirements, and have 1 million houses built to code level 3 and

1 million houses built to code level 6.

In either of the proposed situations, the UK water targets can be achieved and even exceeded

with the development of new water efficient technologies by the year 2020, in addition to

increasing the peoples awareness and minimising water leakages which constitute nowadays a

major problem, contributing greatly to the resulting per capita water consumption. Other

scenarios can also include building and/or retrofitting houses to code level 4 and 5, which

include water standards that meet the governments water targets.

Figure 12: EU countries per capita water consumption (litres/person/day) (from Waterwise, 2006)

Target

scenario

Current

Scenario


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4.4. The need for regional flexibility of the Code for Sustainable HomesThe Code does not account for regional variations concerning water availability. Regional

discrepancies in water availability do not match closely with demand. In southern and eastern

England, rainfall is relatively low yet population and consumption levels are higher. Six

suppliers reported water deficiencies in some supply zones of the east and southeast, two of

which were acute (Water UK, 2008). The following figures illustrate the water situation and

availability in England and Wales, as well as the water consumption per capita in different

regions of the country:

Figure 13: UK per capita water consumption (from Environment Agency, 2008)


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Based on the information provided in the previous figures, it is evident that the balance between

water supply and demand, as well as water availability, varies between the northern-western

regions, and the eastern-southern regions, where water availability and consumption constitute achallenging issue. These regions witness water scarcity along with high per capita water

consumption, which is leading to challenges in the water supply and can lead to problematical

shortages.

Figure 14: Water availability in the UK (from DEFRA, 2008)


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4.4.1.Synergies and trade-offs between water, energy and carbonfootprint

Table 5: Minimum water and energy requirements to achieve each level of the Code (from the Code for Sustainable Homes,

2007)

The current requirement for publicly funded housing in England and Wales is to attain level 3 of

the Code for Sustainable Homes. To achieve a 3 star rating, a residence must have a per capita

consumption of 105 litres/person/day, concurrently with a 25% better percentage in carbon

emissions stated in part L of the Building Regulations (2006), which matches up to: 2,969

kgCO2/year for a detached house, 2,373 kgCO2/year for a semidetached house, and 2,139

kgCO2/year for a 2 bedroom flat (Environment agency, 2009). Nevertheless, The Code does notstate how to best distribute these carbon emissions amongst the main carbon emitting systems

used in a home (stated in chapter 2). For instance, it was established from chapter 2 that the

carbon emissions resulting from water heating relate more to the amount of water used by the

occupant rather than the water efficient fittings, and can only be controlled by reducing the


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amount of water used. Therefore, it would be best to allocate more carbon emissions to water

heating, than to rain water harvesting systems and grey water recycling systems, in regions rich

with water and with high carbon emissions, and acquire water from the mains, which in the UK

has an operational energy and carbon intensities around 40% less than these on-site systems

(Environment Agency, 2009). In arid regions of the east and the south however, on site water

reuse systems are essential. The following figure shows the domestic carbon emissions per capita

(Figure 15) in contrast with the areas of relative water stress (Figure 16) throughout England and

Wales:

From the previous figures, it can be reasoned that, similarly to the situation in the U.S, many

areas where water is abundant (mainly in the western parts) tend to have higher carbon emissions

than areas with water scarcities (in the eastern parts). The western regions with enough water for

abstraction and lower per capita water consumption as well as low levels of water stresses, have

high carbon emissions. On the other hand, the eastern regions where both water stress levels and

per capita consumption are high, lower carbon emissions are detected. Consequently, it can be

affirmed that rain water harvesting and grey water recycling systems are crucial in the regions of

the east, whereas they can be side-stepped in regions of the west, where high rainfall will

increase carbon emissions resulting from rain water harvesting systems (Parkes et.al, 2010).

Figure 16: Areas of relative water stress in the UK (from

Environment Agency, 2007)

Figure 15: Per capita carbon emissions in the U.K (from the

Department of Energy and Climate Change, 2007)


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4.5. Conclusions and recommendationsThe water situation throughout England and Wales is evidently much diversified. The current per

capita water consumption is 150 litres/person/day. The governments target is to reach 130

litres/person/day by 2020. By implementing the Code for Sustainable Homes to achieve this

target, the current mandatory requirement stating that all publicly funded houses must achieve

level 3 of the Code will not be enough even though level 3 dictates a 120 Litres/person/day (less

than government target). The issue remains with the momentous size of existing building stock

not built to code. Many houses must be built to achieve higher levels, in order to minimize the

amount of houses that would need to be retrofitted.

In addition, the Code for Sustainable homes does not account for regional variations when it

comes to water availability and consumption. The requirements are the same in all regions, given

that in the northern and western regions of the UK, water does not constitute a problematic issue

such as in the eastern and southern regions. Based on the findings of this chapter, it appears that

rain water harvesting systems should constitute a requirement in the eastern and southern regions

of England, where rainfall is low and per capita water consumption is relatively high. Grey water

recycling should be implemented in all dwellings built to code, with short retention systems

predominantly, because they have lower carbon emissions and energy intensities than of the

mains (Parkes et. al, 2009).

The following recommendations could improve the applicability of the Code for sustainable

homes in England and Wales:

Including different requirements for different regions of England and Wales. For instance,to achieve a level 3 of the code, a home would be required to have lower per capita water

consumption than of a home built in Wales or the western regions of England.

A weighing factor could be assigned to the regions of the east that can be multiplied by theactual categorys score.

The Code could take into consideration that, as mentioned in chapter 2, the higher therainfall the higher the carbon emissions of rainwater harvesting system, and not include in

its requirement rainwater harvesting systems in areas of Wales and western England, where

water is available, rainfall is high and per capita consumption is low, but redirect points to


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the energy and atmosphere section of the code. In areas where water availability is limited,

it is important to have rain water harvesting systems, in order to reduce the pressure on

local water sources, and to benefit as much as possible from water reuse and rain water,

despite the resulting operational carbon footprint, especially since in these areas, water

consumption is higher than in regions where water availability does not constitute as muchof a predicament, and carbon emissions are relatively low.


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Chapter 5. Green Star for Multi-Unit

Residential (Australia)

5.1. OverviewTwo rating tools are in common use in Australia: the design assessment/rating tool Green Star

and the performance rating tool NABERS (National Australian Built Environment Rating

System). Albeit both expressed in number of stars, the two tools are different in what they

measure. Green Star rates the potential environmental impact of building design at design phase

and/or once built, whereas NABERS rates the actual environmental impact by performance of a

building in use. The two rating systems have been an issue of confusion among people and many

have suggested the integration of both into one holistic system. Another commonly used tool is

the Building Sustainability Index BASIX, an online programme that determines how a building

scores against specific Energy and Water targets. The web-based tool is designed to assess the

potential performance of new homes against a range of sustainability indices: landscape, storm

water, water, thermal comfort and energy.

This study is concerned with assessment tools, evaluating the impact of both design and

performance of residential buildings and so is targeting the Green Star rating tool. Developed by

Sinclair Knight Merz and the U.K based Building Research Establishment in 2003, the tool wasthen taken up and further adapted by the non-profit Green Building Council of Australia (GBCA)

(Saunders, 2008). The Australian Green Star rating system evaluates the environmental design

and performance of Australian buildings against a number of criteria that encompass energy and

water efficiency, indoor environment quality and resource conservation. Green Star has built on

existing systems and tools in overseas markets (Mitchell, 2009),including the BREEAM system

and the LEED system, by establishing individual environmental measurementstandards relevant

to the Australian marketplace and environmental context.


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The Green Building Council of Australia (GBCA) launched the Green Star for Multi-unit

residential v.1 rating tool in 2009 with a goal to promote the design and construction of high-

performance green residential developments. The tool addresses only residential buildings

containing two or more dwellings with over 80 per cent of floor area for residential uses (GBCA,

2009).

Green Star - Multi Unit Residential v1 evaluates the environmental initiatives and/or the

potential environmental impact of new or refurbished multi-unit residential buildings in nine

categories:

Management Indoor Environmental Quality Energy Transport Water Materials Land Use & Ecology Emissions Innovation

Green Star rating systems use six stars to measure performance. Only projects that obtain a

predicted 4 Star rating or above are eligible to apply for formal certification:

Star rating Weighted score Recognition

4 stars 45-59 Best practice

5 stars 60-74 Australian excellence

6 stars 75-100 World leadership

Table 6: Points required to achieve each level of Green Star

Calculating rating points in Green Star in Green Star differ from LEED for Homes and the Code

for Sustainable Homes. Green Star actually accounts for regional environmental variations, and

assigns different weightings among states and territories to reflect the differing importance of

some environmental issues across Australia, as a large and climatically diverse continent.


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The overall score of a project is determined in 4 steps:

1. Calculating individual category score;o Each categorys score isbased on the percentage of points achieved:

2. Applying an environmental weighting to each category (except Innovation);o The weighted category score is calculated as follows:

Weighting factors vary by geographical location, to reflect issues of importance in each state or

territory. For instance, potable water has a larger significance in South Australia than theNorthern Territories, and thus a larger weighting is given in South Australia for the water

category.

3. Adding all weighted category scores together4. Adding any innovation points that may have been achieved


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5.2. The water situation in AustraliaWater is essentially made available to society from surface water in the form of rivers, lakes,

reservoirs, dams and rainwater tanks, and from underground aquifers in the form of wells and

bores (Australian Bureau of statistics, 2010). As an island continent, Australias water supply is

entirely dependent on precipitation (rainfall and snow). Because Australia is the driest inhabited

continent, man-made water storage is vital in maintaining society's water supply. The use of

alternatives to conventional water supply such as effluent reuse, rainwater harvesting and

greywater use are also being encouraged through state-based rebates and the national not-for-

profit Smart Watermark label. Mains water was the most common source of water for Australian

households in 2010, with 93% of households being connected to this source (Australian Bureau

of Statistics, 2010). Despite the majority of Australians having mains/town water supply, many

households also rely on other sources to supplement their water supply. Grey water was the

second most common source of water for households (28% of households) followed by rainwater

tanks (26%) (Australian Bureau of Statistics, 2010).

The current average daily water consumption is 340 litres per person or 900 litres per household

(Riverina Water, 2012). The water consumption levels vary however throughout the country,

ranging from as little as 100 Litres/person/day in some coastal areas, to 800 Litres/person/day in

drier inland areas (Adams, 2010).Water is predominantly consumed by the agricultural industry

which is estimated to use approximately 65% of all water available for consumption. While

domestic households only account for around 14% of water consumption, distributed as shown in

Figure 17, this fraction is susceptible to an upsurge, as the population continues to escalate and

rainfall decreases (Australian Bureau of Statistics Water Account, 2010).

Figure 17: Areas of average domestic usage (Riverina Water, 2012)


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5.2.1.Water shortages and droughtAustralia is the driest inhabited continent on Earth, and among the worlds highest consumers of

water (CSIRO, 2005). Numerous regions have imposed restrictions on the use of water in

response to chronic water shortages resulting from the droughts, which have long plagued the

Murray-Darling, Australia's longest river system and main water resource. At irregular intervals

of two to seven years, the waters of the central Pacific warm up, indicating extreme weather

throughout the southern hemisphere. As a result, torrential rains flood the coast of Peru, while

south-eastern Australia wilts in drought. These periodic weather patterns are known as El Nio.

The duration of these episodes can range from a few months to several years. Consequently, the

flow of the Darling, the longest tributary of the Murray, varies wildly, from as little as 0.04% of

the long-term average to as much as 911% (The Economist, 2007). Water supply is thus highly

vulnerable to droughts, since in most parts of Australia, surface water stored in reservoirs is the

main source for municipal water supply. The Murray-Darling Basin, is currently officially listed

as ''at risk'' by the United Nations Food and Agriculture Organisation (Sheehan, 2012). On the

bright side, long-term droughts in many parts of Australia have changed the way Australians

regard water, which is demonstrated in section 5.4 of this chapter.


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5.3. Overview of Green Star for Multi-Unit residential water criteriaCredit points are available for water efficiency and reuse initiatives such as those listed below:

OccupantAmenity Water

(Max. 5 points)

o Up to two points are awarded for efficient fixtures and fittings; ando Up to three points are awarded for the collection and re-use of non-potable water

LandscapeIrrigation

(Max. 1 point)

One point is awarded where:

o Potable water consumption for landscape irrigation has been reduced by 90%;OR

o A xeriscape garden has been installed.Heat Rejection

Water

(Max. 2 points)


o Potable water consumption of water-based heat rejection systems is reduced by50%.

Two points are awarded where:

o Potable water consumption of water-based heat rejection systems is reduced by90%;

ORo No water-based heat rejection systems are provided.

OR

o The building is naturally ventilated;OR

o The building is Mechanically Assisted Naturally Ventilated (MANV).Fire System

Water(Max. 1 point)


o There is sufficient temporary storage for a minimum of 80% ofthe routine fire protection system test water and maintenance drain-downs, for

reuse on-site; and

o Each floor fitted with a sprinkler system has isolation valves or shut-off points forfloor-by-floor testing;

OR

o The fire protection system does not expel water for testing.Water

Efficient Appliances

(Max. 1 point)


o Dishwasher and clothes washers are installed as part of the base building works;and

o All dishwashers and clothes washers are at or within one pointof the highest available rating under the Australian Government's WELS rating

system as per the WELS Standard AS/NZS6400:2005 Water-efficient Products -Rating and Labelling.

Swimming

Pool/Spa WaterEfficiency

(Max. 2 points)

Two points are awarded where it is demonstrated that:

o A pool blanket is included to prevent water loss from evaporation; ando The potable water consumption has been reduced by at least 70% through any of:

Efficient swimming pool filtration system compared to traditionalsand filtration;

Backwash water is collected and treated for reuse on site; and The pool makeup water is non-potable water.

Table 7: Green star for Multi-Unit residential water criteria (adapted from Green Star Multi-Unit residential rating tool)


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With regards to water standards, the Green star rating tools is well equipped for efficient water

use. It accounts for regional variations regarding water availability and assigns a specific weight

for each of the eight major states and territories in Australia. The weights assigned are as follow:

West Australia15% Southern Australia18% Northern Territory13% Victoria18% Queensland13% New South Wales15% Australian Capital Territory15% Tasmania18%

The regions with the highest levels of water stress, in the southern parts of Australia (Southern

Australia, Victoria and Tasmania2) are given the highest factors.

2Although there is a perception that Tasmania's water resources are plentiful, the fact is the distribution of water

resources there is extremely uneven, as the highest rainfall occurs in the West, whilst conditions are far drier in

many of the farming regions and populated areas (Australian Bureau of Statistics, 2010).


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5.4. Water shortages resulting in increased awareness and watersavings

Because Australia witnessed a devastating drought that went from 2000 to 2010 (sometimes

known as the millennium drought), an increase in population awareness and efficiency in the use

of water has been recorded. In March 2010, 32% of households with dwellings suitable for a

rainwater tank had a rainwater tank installed compared with 24% in 2007 (Figure 18). South

Australia continues to have the highest proportion of households with rainwater tanks followed

by Queensland (57% and 42% respectively of households in 2010). The largest increases

between 2007 and 2010 occurred in the Australian Capital Territory (more than doubling from

8% to 18%), Victoria (from 21% to 36%) and Queensland (from 26% to 42%).

Figure 18: change in amount of rainwater tank installed (from ABS, 2010)

Since the introduction of water restrictions, increasing numbers of households have installed

water conserving devices, including dual-flush toilets and reduced-flow shower heads. In 2010,

86% of households had at least one dual-flush toilet, up from 55% in 1998. At least one water-

efficient shower head was installed in the dwellings of two-thirds of Australian households

(66%), up from 32% in 1998.

Figure 19: change in the amount of houses with water saving products (from ABS, 2010)


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When the South Australian Government introduced the Permanent Water Conservation Measures

in 2003 and the tighter Level 3 Enhanced Water Restrictions in 2007, the result in South

Australian households was a reduction in their daily household water consumption by 16%

between 2003 and 2004, and by 21% between 2007 and 2008 (Australian Bureau of statistics

Water Account, 2010). For the period 2001 to 2010, South Australia's households also became

more active in taking measures to save water indoors and in their gardens, which, according to a

survey by the Australian Bureau of Statistics (2010 census), included:

In the bathroom:

Takingshorter showers:36% of South Australia's households compared with 37%nationally.

Turningoff tap while cleaning teeth/shaving:23% of households compared with 24%nationally.

Installed water saving product:13% of households - compared with 11% nationally. Collecting grey water:12% of households - compared with 9% nationally.

In the laundry:

Operating washing machine only when fully loaded: 25% of South Australia'shouseholds compared with 27% nationally.

Collecting grey water: 14% of households compared with 11% nationally. Buying a water efficient washing machine: 14% of households compared with 11%

nationally.

In the kitchen:

Dont leave tap running:15% of South Australia's households compared with14% nationally.

Wait until sink full before washing dishes, 15% of households compared with 13%nationally."

Operating dishwasher only when fully loaded: 11% of households compared with 12%nationally.

The fact that these measures have been taken by the South Australian community show that

governmental policies and regulations are actually influential and can greatly help raise

awareness. The per capita water consumption in Australia remains high (340 L/p/d), however

this is mainly due to the agricultural and landscaping water requirements. Domestic water

consumption however seems to be relatively manageable.


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5.5. Conclusions and recommendationsWhen it comes to managing water consumption, green star comprises reliable standards. Water

being one of the most crucial and threatening issues in Australia, it is important that it is given as

much attention as possible. Nevertheless, the tool provides no incentive for efficient management

when the building is in use. Performance in practice may not be as good as the potential,

particularly in relation to on-going energy and water use where building management and

occupant activity play an important role (Hes 2007).

While South Australia's households are mainly reliant on mains/town water supplies, they have

led the way nationally in rainwater harvesting and other water conservation measures.

The following recommendations can be made based on the findings in this chapter: Concerns have been expressed about the tendency for voluntary standards to become part

of mandatory regulation (Mitchell, 2009). Further studies should be conducted on the

effectiveness of Green Star constituting a compulsory requirement for all newly built

residential buildings, in the same way that the Code for sustainable Homes has become in

the UK.

The combination of all rating tools used in Australia in one strategic and comprehensiverating tool, appropriately adjusted for each state, similarly to Green Star state weighting

factors, can increase awareness, decrease confusion and help manage water in buildings.

Once the standards in each of Green Star, Nabers, and Basix are integrated into one

holistic effective tool, an improved management of resource consumption when the

building is in use can be achieved across the continent, and water and energy

consumption can be better tracked and observed.

A design rating tool for homes is important and opportune because of the relatively lownumber of homes nowadays. There are about 8 million households in Australia and the

number will increase with population growth (CSIRO, 2010). NABERS for homes rates

the performance of built homes, however, there is no actual design assessment tool to be

used.


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Chapter 6. A Comparison of the Water Criteria

in the three Green Building Assessment Tools

In tool design,Green Star is similar to BREEAM and LEED, since both Green Star and LEED

were originally based on the BREEAM model. All three are principally design rating tools that

combine points (credits) for specific design features across an analogous range of environmental

categories.Although BREEAM was used as the basis for Green Stars approach, the GBCA has

since adapted Green Stars assessment methods such that they are currently more similar to the

LEED approach (Saunders, 2008), as demonstrated in the table below by the close proportion of

credits awarded to each of water and energy efficiency in both. The following table outlines the

main differences and consistencies between the three studied rating systems:

LEED for HomesThe Code for

Sustainable HomesGreen Star for Multi-Unit

Residential

RatingCertified, Silver,Gold, Platinum

1 to 6 stars 4, 5 or 6 stars

Water efficiency

requirements

Water reuse Irrigation

system

Indoor wateruse

Indoor wateruse

External wateruse

Occupant Amenity Water Landscape Irrigation Heat Rejection Water Fire System Water Water Efficient Appliances Swimming Pool/Spa Water

Efficiency

Percentage of credits

awarded for the water

efficiency category

11.1% of totalcredits

10.1 % of totalcredits

12% of total credit

water efficiency in green building assessment tools

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