- Original design
- Robert Juhasz, 2010
Originally built in 1930, extended and retrofitted in 2011. Cetified as a new built PassivHaus in 2013. A PH extension has just been added to the property.
Design Heat Demand: 12kWh/m2
No heating turned on in 4 years, 20-22C in winter
Air tightness 0.44 m3/m3/h @ 50 Pa
Relative Humidity: It was 55-60% for 2 years using the humidity recovery core in the MHRV, down to 50% with the normal core – more comfortable
For Each Flat
Average UK Consumptionwww.gov.uk
3732m3/yr = 41052kWh/yr
1550kWh/yr (2100kWh/yr without Solar PV)
62% less than before
250m3/yr = 2750kWh/yr
93% less than before
1 household, 1 flat / month
£21 GoodEnergy (£17 cheapest)
1 household / month
1 household / month
No expense, positive balance £8-10
Roof insulation: 500mm glass wool
Insulated solid floor: 180mm XPS, 100mm EPS
External insulation, 200mm Kingspan K5 Phenolic Insulation, 220mm Graphite EPS on the extension – Installer http://ewistore.co.uk, Brentford
PassivHaus certified windows, insulated frames, triple glazing: Variotec EnergyFrame IV, insulated wooden frame, alu cladding
Air tightness: 0.44m3/m2/h @50Pa
Mechanical Heat Recovery Ventilation: Paul 300F, 93% efficiency PH Certified (the British Standard for efficiency of MHRV is very misleading)
High efficient condensing boiler with Class A pump, that can modulate down to 3.9kW – Wolf CGB11, cyclinder also has to be very insulated. Very smart thermostat that controls heating, hot water and solar.
Secondary hot water circulation for instant hot water at taps
Low performance radiator system calibrated to 50C > 40C (important that temperature is lower than in traditional systems) – we have 11 in the 2 flats, but we almost never used them in 4 years and removed 2 of them as they were in the way
Solar Thermal System: 3 panels on the south roof Wolf TopSon F3-1
Solar PV: 3.75kW system, 15 panels:Renesola 250W Virtus II 2nd Gen Poly, Inverter, SMA SB3600TL-21 SunnyBoy Dual Tracker, Installer: Solar LDN, Ealing
Cradle to grave embodied energy of the energy upgrade materials, appliances (insulation, concrete floor slab, renders, air tightness materials, MHRV, boiler, windows, cylinder for the entire house) is around 100MWh, as much as we could calculate it. Yearly saving is 37MWh making the energy ROI 2.7 years. This might be somewhat more when the 'cradle to grave' cost is taken into account.
We estimate the expenses solely related to the energy upgrade to £50000 for the two flats. This includes all insulations, windows, doors, additional architect fees, appliances, solar thermal, solar PV. The difference in yearly costs is about £2500, so the cost ROI is around 20 years.
It was worth it. Higher comfort, no mould, good air quality.
In UK it is a rich man's game
Material would not cost too much, for a new build it would be only 10 per cent more to build a house that requires little or no energy – for a retrofit it is invasive
Design is an important element (use PHPP program)
Construction is hard and painful to a PH quality: very invasive, all or nothing
Secondary circulation for hot water – very comfortable, but unless pipes super insulated should not be used, use microbore piping instead
MHRV: great, comfortable, no humidity recovery core is needed, 50% relative humidity all year – clothes dry next day!
Not a great idea to put your ventilation unit in the loft.
Avoid your services penetrating air and thermal envelope