monitoring passive house

Passivhaus monitoring

Dr. Paola Sassi Programme leader MSc Sustainable Building: Performance and Design

Department of Architecture, Oxford Brookes University Sassi Chamberlain Architects

THE BUILDING DESIGN AND CONSTRUCTION

Ground floor First floor

Mezzanine

North Elevation South Elevation

Achieving low energy buildings PRINCIPLES FOR LOW ENERGY DESIGN

APPROACH ADOPTED BY PASSIVHAUS

Step 1 – reduce energy requirements through passive and fabric design

•   Well insulated building fabric - Compact and well insulated building envelope with U-value of less than 0.14 W/m²K AND U-values of windows including glass and frame not to exceed 0.8 W/m²K AND minimise cold bridging

•   Airtight structure - maximum 0.6 air changes per hour

•   Passive solar heating - South orientation of living spaces with maximum glazing on south side of building and minimal overshadowing

Step 2 – provide services through efficient means

•   Ventilation with heat recovery of stale air. Mechanical ventilation with heat recovery with over 80% efficiency. Passive pre-heating of fresh air entering the building, possibly through a earth ducts

•   Appliances to be energy efficient

Step 3 – provide energy from low /zero CO2 energy sources

•   Adopt renewable energy sources if possible

Step 1

reduce energy requirements through passive and fabric design

Wall & roof construction

U-value 0.13W/sqmK

•   Ply finish to walls

•   Plasterboard for fire protection

•   100mm service void insulated with hemp

•   Vapour control layer

•   200mm structural frame insulated with hemp

•   80mm timber fibre insulation

•   Render/ timber cladding finish

Minimise heat loss and gains with insulation

Inward opening windows with min. 50mm insulation covering the frame externally

Minimising heat loss by minimising cold bridges

Minimising heat loss by minimising infiltration losses

South elevation North elevation

Maximising solar gains

Transmission Losses Heat Gains Solar Radiation

kWh/a kWh/a 0 0

709 1334 0 0

207 64 152 98

1068 1496

Transmission Losses Heat Gains Solar Radiation

kWh/a kWh/a 0 0

1933 1937 0 0

518 104 152 98

2604 2139

U-value windows 0.7W/m²K U-value windows 1.6W/m²K

Orientation and insulation

Step 2

provide services through efficient means

Mechanical ventilation with heat recovery (92%)

energy efficient appliances and lighting

Step 3

provide energy from low and zero CO2 energy sources

2993 CO2 kg/a without renewables

546 CO2 kg/a savings from PVs

864 CO2 kg/a savings from solar thermal

1583 CO2 kg/a with renewables

Solar thermal panels and photovoltaics (1.25kWp)

BUILDING ASSESSMENT AND POST OCCUPANCY BUILDING MONITORING

Aim: establish what design and construction contributes to minimising human impacts on the planet

Questions

Has the building achieved the Passivhaus targets? •   Maximum heating requirements of 15 kWh/m²a •   Maximum air changes per hour 0.6 •   Maximum total primary energy requirements of 120 kWh/m²a

Does it represent a minimal impact dwelling? •   Energy consumption: maximum 120 kWh/m²a primary energy •   Water consumption: maximum 80 ltrs per person per day •   Material use and waste: max. non-closed loop materials 80kg/m² •   Satisfactorily provides a healthy and comfortable environment

Does it enable a low impact lifestyle? •   Ecological Footprint

Airtightness test ground floor flat •   1.8 m³/m² = 2.7air

changes/hr

first floor flat •   1.3 m³/m² = 1.7air

changes/hr

Has the building achieved the Passivhaus targets?

Does it represent a minimal impact dwelling?

•   Energy consumption: maximum 120 kWh/m²a primary energy •   Water consumption: maximum 80 ltrs per person per day •   Material use and waste: max. non-closed loop materials 80kg/m² •   Satisfactorily provides a healthy and comfortable environment

Flats Modelled primary energy consumption (PHPP)

Monitored energy consumption over 2 years

Ground floor 101 kWh/m²a 109 kWh/m²a

First floor 93 kWh/m²a 37 kWh/m²a

Create a healthy living environment

•   All materials are associated with minimal off-gassing of formaldehyde and other volatile organic compounds

•   Hygroscopic materials (hemp and timber) help balance the humidity of the building

•   Ample natural light provided throughout

Design for closed loop material cycles

•   Most materials can be either composted or recycled

•   Most building elements can be dismantled

Minimal water use

•   Low water use sanitary ware

•   Rainwater for garden use

Ground floor First floor

Mezzanine

North Elevation South Elevation

Occupant interviews

•   L: Do you feel that your standard of living has changed since you have been living here? You can deal with cooler weather more because of living here?

•   Y: No, not at all, I don’t think it has affected my standard of living at all. •   L: You would still put on a heat if you were cold? •   Y: Yea, you become more aware if you like. You start thinking, OK if I have this light on then any

sort of energy that I might have generated, I might have created goes out the window because I have a light that shouldn’t be on, so yes you do become aware of things but then you have guests and they have no idea. You’re like, don’t put the onion in that bin, and put it in that one!

•   L: Do you feel you are quite aware of energy usage and that you’re self chose this house because of that?

•   Y: I chose this house because every other house I was shown was the same. It was the most interesting house that I was shown, I think I saw all of Cardiff when I came here, and then of course everything was explained. But it wasn’t on that basis

•   L: Once you lived here you became more aware of it? •   Y: Yea •   L: Do you feel you appreciate different things? •   Y: Yea, the estate agent even said ‘So now we’re going to a weird place’-I responded ‘yes! Let’s

go to this weird place!’

Energy consumption and costs

Flats Monitored energy consumption over 2 years

Energy costs including standing charges per year

Energy costs per sq m including standing charges per year

Ground floor 109 kWh/m²a £300 £6.63 First floor 37 kWh/m²a £140 £2.46 ratio of flats 1:3 1:2.7

Building design •   Hot water cylinder position •   Rooflight orientation •   Fuel source •   MVHR

User impact •   educating over and over •   assumptions about comfort

Improvements and lessons learnt

energy to CO2 emissions

Grid electricity 0.537 kg CO2/kWh

Natural gas 0.185 kg CO2/kWh

LPG 0.214 kg CO2/kWh

Wood pellets 0.025 kg CO2/kWh

Carbon dioxide emission: further reductions









Alternative hot water and heating from gas

Existing hot water and heating electric

Building design •   Hot water cylinder position •   Rooflight orientation •   Fuel source •   MVHR

User impact •   educating over and over •   assumptions about comfort

Improvements and lessons learnt

CO2 emissions from buildings and activities

Typical levels of CO2 generation by the average family

Tonnes of CO2 /yr

New house built to modern Building Regulations

4.5

Older house pre 1960 10

Family car use 4.5

Family holiday to the Mediterranean

2.5

Family food 4

Does it enable a low impact lifestyle? Ecological Footprint

farmer’s market

shops

station

station

work

park

Calculation of ecological footprint www.myfootprint.org

There are only 15.71 global hectares available per person on a renewable basis.

Questions

Has the building achieved the Passivhaus targets? •   Maximum heating requirements of 15 kWh/m²a •   Maximum air changes per hour 0.6 •   Maximum total primary energy requirements of 120 kWh/m²a



IS IT FEASIBLE?

Energy efficient versus Ecological: cost comparison Bld Regs equivalent - Option 1 (base)

additional cost compared to base

percentage increase on base

total paid £168,303.08

Yearly mortgage payments (6.45% interest repayment mortgage for 25 years) £13,572.00 Yearly energy costs based on PHPP £1,656.26

yearly mortgage payments + energy running costs £15,228.26

NON-energy efficient and NON-eco - Option 2

total paid £169,232.40 £929.31 0.6%

2 - yearly mortgage payments (6.45% interest repayment mortgage for 25 years) £13,644.00 2 - Yearly energy costs £1,262.17


Energy efficient but NON-eco - Option 3

total paid £192,751.25 £24,448.17 14.5% 3 - yearly mortgage payments (6.45% interest repayment mortgage for 25 yrs) £15,540.00 3 - Yearly energy costs £336.87


Yearly mortgage payments (5.45% interest repayment mortgage for 25 years) £14,124.00

yearly mortgage payments (5.45) + energy running costs £14,460.87

Built option - energy efficient AND eco - Option 4

total paid £199,090.43 £30,787.34 18.3% 4 - yearly mortgage payments (6.45% interest repayment mortgage for 25 yrs) £16,056.00

4 - Yearly energy costs £336.87


Yearly mortgage payments (5.45% interest repayment mortgage for 25 years) £14,592.00

yearly mortgage payments (5.45) + energy running costs £14,928.87

Energy efficient versus Ecological: cost comparison

Thank you

monitoring passive house

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