Greentomatoenergy has completed the renovation of two Victorian terraced houses in West London to the super-low energy passive house standard, reducing the buildings’ carbon emissions and heating bills by more than 80%.
The first of their kind in the UK, and amongst only a handful in the world, the two houses have been converted from cold, draughty buildings to warm, comfortable living spaces for the 21st century.
The completion of the projects comes just as the Department of Energy and Climate Change releases its draft Carbon Plan, in which it states: “Almost half of the UK’s greenhouse gas emissions are from the energy used to generate heat, with the vast majority of our homes still relying on fossil fuel powered gas boilers and with much of our building stock still poorly insulated and inefficient.
“There is a huge opportunity here, not only to cut greenhouse gas emissions and emissions of harmful pollutants, but also for households and businesses to save money, with the most significant and cost effective opportunities likely to come from better insulation and from replacing inefficient heating systems.”
The passive house projects – one private home and one social housing property - have taken 10 months to complete and have included the installation of a wide range of energy efficiency and renewable energy measures. These include:
- Super-insulated walls
- Triple-glazed windows
- Solar thermal and solar electricity panels
- A draught-proof internal environment and ventilation system with heat recovery
- Basement floor ground-to-air heat exchanger
- Careful detailing to avoid thermal bridging and condensation
Neither house has a boiler, nor any radiators - any heat the houses need comes from people inside, light bulbs and appliances, with occasional backup from a small air-source heat pump in the ventilation system. 60-70% of the hot water comes from solar panels, with the remainder topped up by the same air-source heat pump. The actual “in-use” performance of the occupied houses will be closely monitored.
On one project, greentomatoenergy acted for a private client seeking the exceptional internal comfort of a passive house without having to move away from his central London Victorian Terrace.
On the other house, greentomatoenergy acted for social housing provider Octavia Housing2 in a consortium led by build contractor Ryder Strategies Europe Ltd, which also delivered the private home. This project was part of the Technology Strategy Board’s “Retrofit for the Future" competition to renovate existing social housing to low energy exemplars.
The extra cost of building to this level of eco-friendliness was 15-20% on top of the conventional refurbishment works that were happening anyway. Energy bills in each property are expected to drop at least 75%, with one of the houses expecting gas and electricity bills to be only £100 per year.
Both houses are in conservation areas, meaning that their external appearance was not allowed to change as a result of the build. In response, these projects led to the local production of new, tripleglazed sash windows by the contractor Ryder Strategies Europe Limited and the installation of a lowprofile, integrated solar thermal system into the roof.
Passive house (or “passivhaus” in its original German spelling) is a voluntary building standard and integrated design process for creating ultra-low energy buildings. Developed in mainland Europe over the last 20 years, it is rapidly gaining recognition internationally as a gold standard for comfort and energy efficiency in buildings.
To meet the standard, the total annual energy demand for space heating and cooling must be below 15 kWh per m2 of floor area and the total primary energy use for all appliances, domestic hot water and space heating and cooling must be below 120 kWh/m2. The house must also be airtight to a level of 0.6 air changes per hour at standard test pressure of 50 Pa.
philip o brien, ireland around 1 year, 2 months ago