passive house principles for hot humid climates

Passive House Strategies for

Hot and Humid Climates

Gulf Coast Green 2013

Hot and Humid Climates

Overview

1 Passive House Core Philosophy

2 Passive Building Metrics and Principles

3 Climate Specificity3 Climate Specificity

4 Enclosure Strategies

2© Passive House Institute US 2013

Passive House Core Philosophy

Part One: Passive Building Principles

Optimize Orientation

Super-insulate + Air Seal

Optimize Window Performance

Passive House Design Order of Operations

Optimize Window Performance

1st Utilize Passive Space Conditioning Strategies

2nd Utilize High Efficiency Active Strategies

Then…Zero Out with Onsite Renewables

…then zero out the remaining energy with active PV

and generate plus energy for electric mobility…

Passive Buildings: Most affordable Way

to make Zero / Plus Energy Reality

(Image source: Terry Hill, Berlin Germany)

Conventional Approach:

Sizing Mechanical Systems

(over)size the system to the shell

Conventional Approach:

Passive House Approach:

Sizing Mechanical Systems

Size the Shell to the Heating System

Passive Building Metrics and

Principles

Global CO2-Emissions 2006 per Country –

determining a Carbon Metric

Countries by carbon dioxide emissions in thousands of metric tones per annum,

via the burning of fossil fuels (blue the highest)

(Source: Wikimedia Commons 2006)

energy-efficiency

geo-/ozean. power

windpower

waterpower

new biomass

trad. Biomass

Worldwide Energy Resources and Consumption

1890 1910 1930 1950 1970 1990 2010 2030 2050 2070 2090

trad. Biomass

nuclear

Reference: Shell-Study (till 2005), Scenario with high efficiency and regenerative usage of energy

Standards & Rating Comparison

One Certification – Three Labels

PHIUS+, Challenge Home, Energy Star V3

Mostly PrescriptiveMostly Performance

Step1: 15-30%Step 2: 40-60%Step 3: 70-85%100

±±±±0

One Certification – Three Labels

PHIUS+, Challenge Home, Energy Star V3

The 2030 Challenge Brought Forward by Architect Ed Mazria

Passive Buildings

Human Comfort Cold Winter

Interior

Feels chilly and drafty: uncomfortable!

Conventional Code

House – Typ. 2x4 wall

(actual R 10)Double glazed window – R 3

Factors affecting

Comfort:

• Air Temperature (dry

bulb º F)

• Relative Humidity (%)

•Air Velocity (ft/min)

Outside

Temperature 0º FGlass

Surface

51.2º F

Interior

Walls 68º F

Exterior

Walls 62.9º F

• Radiant Conditions(MRT º F or radiation value

BTUh/ft²)

20-50%

Human Comfort Cold Winter

Interior

Feels: comfortable!Temperate glass and wall surfaces and no drafts

PH Example

• R 60Envelope

PH Comfort criteria:

• (68 º F)Air Temp

Surface

62.4º F

Interior

Walls 68º F• R -9 Triple glazed

(Climate specific) Window

• 0º FOutside

Exterior

Walls 67.1º F

RH:40-50%

• (40-60 % for PH)

Relative Humidity

• (<19.7 ft/min)

Air Velocity

• Max Delta T <7.2 º F (4 ºC)

Radiant Condition

Human Comfort Hot Summer

Interior

Feels hot and humid: uncomfortable!

Conventional Code

House – Typ. 2x4 wall

(actual R 10)Double glazed window – R 3

Factors affecting

Comfort:

• Air Temperature (dry

bulb º F)

• Relative Humidity (%)

Outside Temperature

95 º FGlass

Surface

81.4º F

Interior

Walls 77 º F

Exterior Walls

78.3º F

• Radiant Conditions(MRT º F or radiation value

BTUh/ft²)

65-80%

Human Comfort Hot Summer

Interior

Feels: comfortable!Temperate glass and wall surfaces and no drafts

PH Example

• R 30Envelope

PH Comfort criteria:

• (77 º F)Air Temp

Surface

79.7º F

Interior

Walls 77º F

Exterior

Walls 77.4º F

RH: 40-60%

• R -5 Triple glazed (Climate specific)

Window

• 95º FOutside

• (40-60 % for PH)

Relative Humidity

• (<19.7 ft/min)

Air Velocity

• Max Delta T <7.2 º F (4 º C)

Radiant Condition

PH “thermos bottle”

summer comfort with

RH, range without

active cooling:

Natural Ventilation and

Passive Cooling Strategies?

Fig. 4.186 Applicability of building cooling strategies. Alison Kwok, Walter Grondzik: The Green Studio

Handbook, 2e

Adaptive Comfort

• < 15 kWh/m²a (4.75 kBTU/ft2yr) Annual Heat

Demand

• < 10 W/m²or 0.93W/ft2 (3.17 BTU/hr.ft2 )

Peak Heat Load

• < 120 kWh/m²a (38 kBTU/ft2yr) Primary Energy

Demand

• ≤≤≤≤ 0.6 ACH50

Airtightness

Baseline Criteria - Heating

*Note: Window and Thermal

envelope criteria Listed are for a

cool moderate heating dominated

Climate. Recommendations for

these values may vary based on

climate

• ≥≥≥≥75% Recovery, ≥0.45 W/m³ (0.76 W/cfm)

Ventilation

• U ≤≤≤≤ 0.15 W/m2 K (R ≥≥≥≥ 38.5 hr. ft2°F/BTU,)

Thermal Envelope:

• Ψ ≤≤≤≤ 0.1 W/ mKThermal-bridge Free

• Uw-install ≤≤≤≤ 0.85 W/m2 KWindows installed:

• 50 – 55 %SHGC

≈10 W/m² or

1 W/ft²

• < 15 kWh/m²a (4.75 kBTU/ft2yr )Annual Cooling

Demand

• < 10 W/m²or 0.93W/ft2 (3.17 BTU/hr.ft2 )

Peak Cooling

• < 120 kWh/m²a (38 kBTU/ft2yr) Primary Energy

Demand

• ≤≤≤≤ 0.6 ACH50

Airtightness

Baseline Criteria - Cooling

*Note: Criteria in blue are

based on a Central European

heating dominated climate.

Recommendations for these

values will vary In N America

cooling dominated climates!

• ≥≥≥≥XX% Recovery, ≥0.45 W/m³ (0.76 W/cfm)

Ventilation Cooling

• U ≤≤≤≤ 0.15 W/m2 K (R ≥≥≥≥ 38.5 hr. ft2°F/BTU)

Thermal Envelope:

• Ψ ≤≤≤≤ 0.1 W/ mKThermal-bridge Free

• Uw-install ≤≤≤≤ 0.85 W/m2 KWindows installed:

• 50 – 55 % (??)SHGC

≈10 W/m² or

1 W/ft²

Five Main Passive Building Principles

+ Renewables= Zero/Plus Energy

Envelope Losses

+ Gains

HP Windows Losses

+ Gains

Balanced Ventilation +

Heat/Moisture Recovery

Airtightness

Losses + Gains

Hygrothermal

Performance

Passive Energy

Balancing as Basis for

Zero/Plus Energy

Structural insulated panels

P1: Continuous Insulation

Insulated Concrete Forms

Masonry Structure w/FoamglassVarious Passive House applicable

Wall Type Sections24© Passive House Institute US 2013

P1: Avoiding Thermal Bridging

Source: Building Science Corporation Newsletter #49: Aqua Tower and Infra Red by Fluke Corp

P2+3: Continuous Air-Tight & Wind-Tight

Layer- The Red line Rule

Air-tight Layer: 0.6 ACH50!Factors affected by air

tightness:

• Moisture Performance

of wall

• Heat loss through

RED LINE RULE

• Draw continuous air

barrier

Wind tight Layer

• Heat loss through

• Comfort, no drafts!

barrier

• Identify each air

barrier component

• Identify connection

between them

P4: High Performance Windows(P

Definition of a thermal bridge:

A building element which has a

linear thermal transmittance of

greater than 0.006 BTU/(hr ft °°°°F)

The highly efficient Window Profile – warm

climates, SHGC needs to be minimized!

Exterior surface

temperatures can

get to 160 F!

Passive Solar Opportunities

and Challenges

Venetian Blinds, trellises,

overhangs, balconies, decks,

trees etc.

Exterior Shading Devices

http://www.warema.com

1. Ventilation

2. Dehumidification

3. Cooling

P5: Balanced Ventilation System

With Minimal Space Conditioning

3. Cooling

4. Heating

5. Domestic Hot

Image source: www.greenbuildingstore.co.uk/mvhr.php

Most Popular Ventilation Models

UltimateAir 200DX (ERV)Zehnder ComfoAir 350

(ERV/HRV)

Night-time cooling

Passive Cooling(Image Source: passive-on.org)

PH Cooling-Passive Design Strategies

Ground cooling Source: Zehnder

Heat Recovery BypassGround Temperature @ 3-4m (10-13 ft) =

Annual Mean Air Temperature ±±±±2 ºC (4 ºF)

Radiative cooling

Evaporative cooling

Heating, Cooling and Dehumidification

(Images:http://compressors.danfoss.com/)

Samsung Mini-Split Air-to-Air Heatpump 20 SEER, point source

Samsung EH slim ducted Mini-

Split, integrated in ventilation

ductwork

Heating and DHW

(Image: www.enerworks.com)

Climate Specificity

Part Two:

Heating Degree DaysHeating Degree Days

Cooling Degree DaysCooling Degree Days

Winter Design TempratureWinter Design Temprature

Summer Design TemperatureSummer Design Temperature

Passive Building is Climate Dependent!!

Summer Design TemperatureSummer Design Temperature

HumidityHumidity

Solar RadiationSolar Radiation

Night Sky RadiationNight Sky Radiation

Ground TemperatureGround Temperature

Latent vs Sensible Ventilation Load

Indexes

U.S. has more climate zones

than the

entire European Union!!

(Image Source: from ASHRAE Journal, November, 1997 pp 37 - 45)

Image Source: www.energycodes.gov

Climate Specific Space Conditioning

Requirements

Graph Courtesy of Global Buildings Performance Network

heating and

dehumidification

cooling and

dehumidification

66-76F

-3000 -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000

Qsensible (watts)

heating and humidification

cooling and

humidification

Grafics: Newell Instruments, Inc.

SI Units IP

1 Heat Load: ≤10 W/m2 ≤ 1 W/ft2

Cooling Load: ≤ 8 W/m2 ≤ 0.8 W/ft2

2 Envelope Insulation:2 Envelope Insulation:Very Cold/humidVery Cold/humid Minneapolis, MNMinneapolis, MN U≤0.08 W/mU≤0.08 W/m22KK R≥71 hrR≥71 hr--ftft22--°°F/BtuF/BtuColdCold Chicago, ILChicago, IL U≤0.094 W/mU≤0.094 W/m22KK R≥60 hrR≥60 hr--ftft22--°°F/BtuF/BtuMixed/humidMixed/humid Ashville, NCAshville, NC U≤0.14 W/mU≤0.14 W/m22KK R≥40 hrR≥40 hr--ftft22--°°F/BtuF/BtuMixed/dryMixed/dry Las Vegas, NVLas Vegas, NV U≤0.14 W/mU≤0.14 W/m22KK R≥40 hrR≥40 hr--ftft22--°°F/BtuF/BtuMarine Marine Seattle, WASeattle, WA U≤0.13 W/mU≤0.13 W/m22KK R≥44 hrR≥44 hr--ftft22--°°F/BtuF/BtuHot/humidHot/humid Houston, TXHouston, TX U≤0.16 W/mU≤0.16 W/m22KK R≥35 hrR≥35 hr--ftft22--°°F/BtuF/Btu

Climate Specific Recommendations Passive House

Hot/humidHot/humid Houston, TXHouston, TX U≤0.16 W/mU≤0.16 W/m KK R≥35 hrR≥35 hr--ftft --°°F/BtuF/BtuHot/dryHot/dry Phoenix, AZPhoenix, AZ U≤0.16 W/mU≤0.16 W/m22KK R≥35 hrR≥35 hr--ftft22--°°F/BtuF/Btu

3 Thermal Bridge Free Construction:3 Thermal Bridge Free Construction:Linear Thermal TransmittanceLinear Thermal Transmittance ΨΨ≤0.01 W/≤0.01 W/mKmK ΨΨ≤0.006 Btu/hr≤0.006 Btu/hr--ftft--°°F F

4 High Performance Windows installed:4 High Performance Windows installed:Overall Thermal Transmittance (Very Cold)Overall Thermal Transmittance (Very Cold) UU≤0.6 W/m≤0.6 W/m22KK UU≤0.11 Btu/hr≤0.11 Btu/hr--ftft22--°°FFOverall Thermal Transmittance (Cold/Mixed)Overall Thermal Transmittance (Cold/Mixed) UU≤0.85 W/m≤0.85 W/m22KK UU≤0.15 Btu/hr≤0.15 Btu/hr--ftft22--°°FFOverall Thermal Transmittance (Hot)Overall Thermal Transmittance (Hot) UU≤1.55 W/m≤1.55 W/m22KK UU≤0.27 Btu/hr≤0.27 Btu/hr--ftft22--°°FF

Solar Heat Gain Coefficient (Mixed/Cold) g-value≥50% SHGC≥50%Solar Heat Gain Coefficient (Hot) g-value ≤ 30% SHGC ≤ 30%

5 Heat Recovery Ventilation:Net Efficiency η≥80% η≥80%

Electric Consumption of motor ≤0.45 Wh/m3 ≤0.76 W/cfm

Climate on the Move

Source: www.globalchange.gov

Enclosure Strategies

Cold and Humid Climate Wall Assembly - Chicago

Vapor Drive

End of Feb

End of Oct

End of Jul

Spring and Fall

Winter

SummerEnd of Jul Summer

Wall Assembly Warm Humid Climate -Houston

Vapor Drive

End of October

End of February

End of July

Spring and

Winter

Summer

Orientation and Shading a Must:

Windows to the N, S and E-W limited

LeBois Project – 2010, Lafayette, LA

North American Passive Building

Uptake 2003-2013

PHIUS Certifications over

last 10 Years in US and Canada

PHIUS Certification Programs:

PHIUS Certification Programs

PHIUS Certification

PHIUS Certification Programs:

�Certified Passive House Consultant,CPHC®

�PHIUS Certified Builder

�PHIUS+ Certified Rater

�PHIUS+ Certified Passive House Projects

�Window Performance Data Verification Program

PHIUS+ Certified Passive Projectswww.passivehouse.us/projects

48 certified and

pre-certified

Projects, Projects,

Total of more

than 130

projects

currenty

Registered in

National Data

Base to be

www.passivehouse.us/consultants

Certified Passive House Consultants (CPHC®)

421 Certified

Professionals Professionals

currenty listed

in National

Data Base!

Passive House Alliance US

Save the Date!

October 16-19, 20138th Annual North American Passive House

7th7th7th7th Annual North American Passive House ConferenceAnnual North American Passive House ConferenceAnnual North American Passive House ConferenceAnnual North American Passive House ConferenceSeptember 27September 27September 27September 27----30, 2012 Denver CO30, 2012 Denver CO30, 2012 Denver CO30, 2012 Denver CO

8th Annual North American Passive House

Conference, Pittsburgh, PA

Katrin Klingenberg

katrin@passivehouse.us

Executive Director | PHIUS

Thank You!Thank You!

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