mind the gap - what can passive house design teach us about closing the building performance gap?
TRANSCRIPT
Let’s talk about:1. What is the building performance gap?
2. Why does it matter?
3. Reasons for the gap
4. Passive House design
5. Results
1. What is ‘the gap’?When building performance in use doesn’t match design predictions
1. Energy Consumption
2. CO2 emissions
3. Health and wellbeing• Comfort• Hygiene• Indoor Air Quality
What is the gap?When building performance in use doesn’t match design predictions
1. Energy Consumption
2. CO2 emissions
3. Health and wellbeing• Comfort• Hygiene• Indoor Air Quality
Health and WellbeingComfort• Air temperature, surface temperatures, temperature
asymmetry, draught-free, relative humidity
Hygiene• Condensation, mould
Indoor Air Quality• Fresh air, odours, CO2 levels, moisture
2. Why does ‘the gap’ matter?People see sustainable design as:• Woolly• Well intentioned, but . . .• Expensive / luxury• An add-on extra• Pointless
They are right . . .. . . while there is a performance gap.
Close ‘the gap’ and . . .
Sustainable design is• Not woolly: clearly defined outcomes• Not just good intentions: delivers on promises• Not luxury: what educated clients demand• Not an add-on: integral to design• Not pointless: relevant
AND genuinely helps mitigate climate change
Design• Designers don’t know the impact of decisions• No modelling• Wrong / unknown modelling assumptions• Wrong assumptions about how people behave• Designs unbuildable
Construction• Drawings / documentation not followed• Changes made during construction• Lack of quality control
Occupation• Complex systems that people don’t know how
to use• Not educated in using a building efficiently• Don’t care?
4. Passive House design• Clear performance requirements• Rigorous non-prescriptive design methodology• Modelling integral to the design process• Design QA• Construction QA• Rigorous 3rd-party verification process• Accountability
A focus on what matters1. Insulation
2. Airtightness
3. Heat Recovery Ventilation
4. Thermal Bridges
5. Windows & Doors
Why is PHPP so accurate?• A design tool• Instant• Transparent• Parametric• Useful
• Simplified• Steady state• Only what’s needed
• Detailed
• Verified• Dynamic simulation• Real world results• Constant improvement
5. ResultsEnergy Consumption / CO2 Emissions• Heating• Energy
Health and Wellbeing• CO2 levels• User comfort / satisfaction
Heat Loss• 12
PHEv
eryt
hing
else
Co-heating test resultsCentre for the Built Environment, Leeds Metropolitan University
Energy ConsumptionkW
h/sq
m /
yea
r
0
50
100
150
200
250
2013 2014 2013 2014 2013 2014 2013 2014 2013 2014
CIBSE CIBSE TM46 BREEAM2Very2Good BREEAM2Excellent Passivhaus Passivhaus Passivhaus
Typical Good2pracGce
Median Willows St2Lukes Oakmeadow Bushbury Wilkinson
70+
% re
duct
ion
Takeaways: to close the gap• Clear measurable targets
• Model accurately and often to measure design
• Measure completed buildings and learn
• Accountability throughout the process