CASE STUDY:200 HOUSE LOW ENERGY LOW CO2

DEVELOPMENT AT KILLEAGH, CO. CORKThe rapidly growing public interest in sustainable building is finally starting to impacton property developers. Bill Quigley of Nutech Consultants describes an innovative200 house development currently on site in Co. Cork where forward-thinking developersJ & W Leahy Brothers have decided that the market is ready for low energy, low CO2

building.

Probably one of themost exciting large scalelow energy/low CO2

housing projects inEurope is being con-structed at present inKilleagh, Co. Cork.

The housing at Killeaghfeature the following technologies:

A well insulated fabric with a real U-value which will match the calculated value.

The houses are designed to be very airtight in terms of the unwanted level of air infiltration.

A highly efficient heat recovery ventilation system is fitted which guarantees the level of fresh air ventilation.

An air solar heating system is being used which delivers solar energy to the ventilation and heating system together with the domestic hot water system.

Any required backup energy is being delivered by way of a wood pellet boiler that is sitedin the living room and is integratedwith the air solar heating andventilation system.

NuTech Consultants, in conjunctionwith the Kingspan Century teamdesigned the low energy/low CO2 fea-tures for this housing development.The target was to design a house thatsaved some 95% of the CO2 emissionsassociated with space and water heat-

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ing demands of a standard 3 to 4 bed-room house as typically built by adeveloper.

In this article we will explain the designbrief for the energy systems as set outby the developer/builder, the back-ground to the thinking behind thedesign, the systems and hardwarebeing used and the results in terms ofthe actual construction of the houses.

THE HOUSING DEVELOPMENT ATKILLEAGH, CO CORKThis development consists of 200 hous-es. There will be 2, 3 and 4 bedroomedhouses on the site. Some of these willbe bungalows on fairly large sites. Thesite size is 22 acres and the resultingdensity is roughly 22 houses per acre.

The developer / builder is J & W LeahyBrothers of Middleton, Co. Cork. Thearchitect is Richard McGrath andmechanical services were designed byEDC Consultants Ltd. All of the energycalculations and systems were designedand carried out by the KingspanCentury team with NuTech Consultants.

THE BUILDER/DEVELOPERS REQUIREMENTS& BACKGROUND TO THE DESIGNInitial discussions took place betweenKingspan Century including NuTechConsultants and J & W Leahy Brothersto consider possible designs and sys-tems that could be used to satisfy thespace and water heating demands ofthe houses. Bill Leahy, Director of J &W Leahy's, stated categorically that hedid not want to use oil or gas fired sys-tems as the primary or secondary ener-gy supply units for these houses. Hismain idea was that he wanted to 'futureproof' these houses and his clientsagainst oil price rises and availabilityof supply. This did put some pressureon the design team to come up with adesign and energy supply package thatwas practical, economical and deliver-able within a reasonably short space oftime.

It was explained to Bill Leahy thatKingspan Century with NuTechConsultants recently completed theKingspan Century Formula 1 HouseProject. This project had received sup-port from Sustainable Energy Irelandunder its House of Tomorrow researchand development fund. The team hadarrived at a number of conclusionsprincipally as follows:

Firstly,

Typically, 1/3 of the energy required for space and water heating in a developer type house is accounted for by way of heat loss through the fabric.

The second 1/3 is by way of energy required to counteract the heat loss due to unwanted air infiltration and the necessary air for ventilation.

The third 1/3 is by way of the

Solar panels (opposite & p41) which assist the heat recovery ventilation (HRV) system to pro-vide adequate quantities of fresh air, and also supply the energy for the domestic hot waterdemand. This means that the domestic hot water demand can be reduced by some 60%.Furthermore, it is possible to use the solar air HRV system as the heating system of thehouse, thereby saving in costs. Although general attention to airtightness was based onfactory fitting, proprietary tape and seals are installed on site where necessary (above andbelow left) to ensure airtightness.

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energy required for domestic hot water.

Secondly,

This meant that the energy demand forspace and water heating could bereduced to as low a figure as economi-cally possible by doing the following:

Insulate the houses to as high a level as possible. Ideally thisinsulation should be factory fitted. This deals with the first third of the energy demand.

Make the houses as airtight as is practicable - a level of 0.1 air changes per hour at normalpressure was decided upon.This means that a mechanical ventilation system is required.It was decided to use a solar assisted heat recovery ventilation(HRV) system to provide adequatequantities of fresh air. Thisensures that the second third of the energy demand is greatly reduced.

Utilise the same solar heating system to supply the energy for the domestic hot water demand. This means that the domestic hot water demand can be reduced by some 60%.

Furthermore, it is possible to use the solar air HRV system as the heating system of the house, thereby saving in costs.

Building in highly insulated and airtight construction that is achieved with Kingspan Century's special timber framedesign is a huge advantage.Great use of the 'balanced thermal capacity' of timber frame construction can be made as this allows excellent use of the low level solar gainsthat are available in Ireland in winter.

Having reduced the energy demand toas low a figure as practicable, the ener-gy supply side was addressed. A smallwood pellet stove with a back boilerwas used as the backup energy supplyunit. This stove could be convenientlyplaced in the living room. By way of allof these techniques the KingspanCentury team with NuTech Consultantshad reduced the CO2 emissions of atypical house by some 95%.

Bill Leahy decided, following discus-sions with his fellow directors, to usethese techniques to build the houses atKilleagh such that they would be lowenergy/low CO2 houses that did notrely on oil or gas as the fuel to supplythe space and water heating demand.Furthermore, because the energydemand of these houses is low it wouldnot require a large tonnage of wood

pellets per year. This meant that thesupply of wood pellets could be by wayof the standard 18kg bags rather thanby way of requiring a delivery of 3tonne lots to a storage room.

Bill Leahy had considered the use ofground source heat pumps but rejectedfor a number of reasons. Firstly, if theinstantaneous design heat load wasreduced from as much as 10 kW to aslittle as 3 kW it did not make sense togo to the expense of a heat pump andheating system for such a small load.Secondly, Bill Leahy was not happy withthe potential CO2 savings with such aheat pump. For example, if the heatpump achieved a seasonal coefficientof performance of as much as 4 andwith electricity delivered by the ESB ata primary efficiency of 30% then thismeant that the CO2 emissions wereonly reduced by approximately 20% -this was not what he had envisaged asbeing the best result. NuTechConsultants pointed out to Bill Leahythat heat pumps do have a role to playin certain circumstances but not partic-ularly in this case.

In short, Bill Leahy saw that with thispackage he would be supplying housesto his clients that would offer the fol-lowing major benefits:

Very low running costs for space and water heating by way of the house construction and the fully integrated air solar heating, ventilation and hot water system.

Houses that are 'future proofed' against fluctuating oilprices and indeed the supply of fossil fuels.

High levels of comfort in terms of the average house temperature and humidity in autumn, winter and spring.

An increase in the level of comfort by way of fresh filtered air and a consequent reduction in the risks from dust, pollen, and so on.

A degree of cooling in summerduring both the day and night by way of the fresh air intake.

Finally, the project was put forward toSustainable Energy Ireland for fundingunder House of Tomorrow.

SUPPORT UNDER HOUSE OF TOMORROWThe House of Tomorrow Programmeadministered by Sustainable EnergyIreland (SEI) grant aids projects whosemain aim is to save energy. Basically,energy savings of at least 40% arerequired over the base case house toqualify and the houses must be built toincorporate certain minimum standardsof insulation. The base case house isdefined as the house being built thatwould just satisfy the requirements ofPart L of the 2002 Building Regulations

when considered under the OverallHeat Loss Method or the Heat EnergyRating Method. This means it couldhave U-values as poor as the following:

Ground Floor < or = 0.37 W/m².KExternal Walls < or = 0.37 W/m².KRoofs < or = 0.25 W/m².KWindows < or = 2.20 W/m².K

To comply with the rules of House ofTomorrow the U-values for the variouselements must be as good as or betterthan the following:

Ground Floor < or = 0.20 W/m².KExternal Walls < or = 0.27 W/m².KRoofs < or = 0.16 W/m².KWindows < or = 1.90 W/m².K

The elements of the fabric of the hous-es at Killeagh have been built to satisfyand in some cases are better than theU-values demanded by SEI. NuTechConsultants examined the houses usingtheir hour-by-hour energy analysiscomputer model. This model takesaccount of the following:

The U-values of the elements of the house

The level of airtightness of thehouse

The use of heat recovery ventilation

The use of various areas of air solar collectors to reduce the energy demand for heating ventilation and hot water

The amount of hot water used per day

The level of occupancy in the house

The utilisation of passive solargains and energy attributable by way of gains from occupants

Energy supplied by the boiler with an applied efficiency

Using this model NuTech Consultantsdemonstrated that houses being con-structed by Leahy Bothers would have agross saving in energy for space andwater heating amounting to 75% whencompared to the base case house.

This meant that the maximum grant

aid of 8,000 per house was awardedfor the first 50 houses in this scheme.Results from this project will be fedthrough to SEI over the next few years.The main items of interest are the actu-al running costs in terms of the numberof kilograms of wood pellets used peryear and the level of airtightnessachieved by way of the constructionmethods used.

The House of Tomorrow programme isa most welcome development inencouraging builders to build low ener-gy/low CO2 houses. It allows buildersto become familiar with the principles

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involved in designing low energy hous-es and helps them to see the benefitsnot just for themselves but also fortheir customers. Under the require-ments of the Energy Performance ofBuildings Directive all houses will soonbe energy rated and certified. This willallow the prospective homeowner toassess how energy efficient their newhome is. Most builders will want todeliver an A-rated house to their clientsin the same way as a company such asSiemens deliver an A-rated fridge totheir customers - Siemens do not manu-facture any C-rated fridges.

THE TECHNOLOGIES BEING USEDThe basic concept is as described previ-ously. The technologies used are asfollows:

The Kingspan Century special package of pre-fitted insulationthat has been shown be effectivein terms of its calculated U-value

is the same as its U-value in practice.

This special package has factoryfitted air tightening seals which ensures that the house can achieve an air infiltration rate of less than 0.1 Air Changes per Hour.

The NuTech Consultants designed air solar heating and hot water system with an integrated Heat Recovery Ventilation module. A 3-panel Sunwarm air solar heating system is used here linked to the unique 140 Air Handling Unit designed by NuTech Consultants. A Mitsubishi Lossnay Heat Recovery Ventilation unit is integrated into the system and is controlled by the Sunwarm controller.

A Wodtke wood pellet boiler is used as the backup energy supply system.

This overall system is the heating sys-tem of the house-the ventilation systemis oversized in order to be the heatingsystem of the house also. However, inthe first fifty houses a radiator heatingsystem is being installed on the groundfloor. The bedrooms are heated by wayof the Sunwarm system.

The controls for the system are simple

in that the Sunwarm system is thermo-statically controlled and will controlwhether warm air is delivered to thehouse or not. On a warm sunny day insummer, cool ventilation air will bedelivered to the house while the solarpanels will deliver energy to thedomestic hot water cylinder. On asunny day in winter, energy from thesolar panels will be used to provideboth heat to the domestic hot watercylinder and heat to the house by wayof the ducted air system. The systemis completely automatic and all thehouseholder has to do is set the ther-mostat to the house temperaturerequired. The boiler is also automaticand will be enabled to fire by way ofthe boiler timer and the required tem-peratures in the house and hot watercylinder.

CONSTRUCTION OF THE HOUSESThe construction of the houses hasgone very smoothly. The onsite man-

agement team of Oliver Leahy and AlanHarty has resulted in some impressivetargets being met.

It was found that the KingspanCentury/Leahy Brothers team coulddeliver and erect six houses per weekquite easily. It should be rememberedthat these timber frame houses comepre-insulated and with the airtighteningseals pre-fitted - this speeds up thebuilding process enormously. With lev-els of airtightness of 0.1 Air Changesper Hour being achieved in practice,this is indeed a remarkable level ofprogress in low energy house buildingin Ireland. It has to said that the levelof site supervision by the LeahyBrothers' team and the attention todetail by their sub-contractors has paidhandsome dividends.

The roofing sub-contractors employedby Leahy Brothers have installed theSunwarm air solar collectors. Similarly,the Sunwarm air handling unit, togetherwith the Mitsubishi Lossnay HRV unitand all of the ducting and controls havebeen installed by both the plumbingand electrical sub-contractors to LeahyBrothers. This utilisation of the normalon-site trades has been a huge benefitto the efficient building of the houses.NuTech Consultants trained these per-sonnel in the fitting of the various sys-tems which on completion will be com-missioned by NuTech.

IN CONCLUSIONThis project has gone extremely well

because of the 'build speed' of this spe-cial timber frame construction fromKingspan Century with factory fittedinsulation and airtightening seals.

The utilisation of the existing sitetrades also added to the efficiency.The determination of the builder, thesuppliers, designers and the site teamto build the house as designed suchthat it will perform in practice has beena key element of this project.

In order to ensure this teamwork LeahyBrothers with Kingspan Century andNuTech Consultants organised a confer-ence in the Midleton Park Hotel toexplain to all concerned what technolo-gies were involved and how each sectorwas interdependent with the other.This conference was attended by allconcerned with the project - the designteam, the build team, all of the sub-contractor trades involved, the mechan-ical services team and very importantly

the auctioneers involved in selling thehouses. It was also attended by per-sonnel from the Department of theEnvironment and from HomeBond.

It was felt that, with the attractivedesign of the houses and the carefulintegration of the technologiesinvolved, these houses offer the buyingpublic a wonderful opportunity to owna house that is 'Future Proof' brandedby Kingspan Century against the energysupply and price fluctuation situation.

Proof positive of the success of theapproach taken by Leahy Brothers isthe fact that all of the houses in thisHouse of Tomorrow Project have beensold. Bill Leahy offered houses withthe option that they could chooseeither the 'low energy/low CO2' packageas described above or a standard oil-fired heating system. All of the clientsopted for the low energy house withthe wood pellet boiler as backup. AsBill Leahy says …..'I did have to explainto all of our clients how all of the sys-tems worked and the technologiesbeing used in the houses. It took a lotof talking but, with the high oil pricesand concerns over supplies, all of themwere most pleased to find we wereoffering such a well-developed solutionbeing supplied by large reliable compa-nies such as Kingspan Century, NuAireLtd and Mitsubishi Ireland. Once theysaw the benefits they all went for thelow energy package on offer'.