London, Twickenham, Amyand Cottages
- Photovoltaic panels (2.5kWp) on pitched & flat roofs
- Air source heat pump for central heating – radiators fitted with TRVs
- Solar hot water from 20 Viessmann vacuum tubes, supplemented by inline electric water heating when required
- LED lighting
- o Triple glazing throughout
- o Roof insulation with multi-layer foil (Tri-iso 9)
- o Under-floor insulation throughout ground floor (90mm foil backed Celotex)
- o External walls insulated internally with Aerogel or Celotex (75% completed)
- o Doors: Front – Grabex A-rated composite door 1.0 Watts/m2/K, draught excluding letterbox; Rear – Ecoplus triple glazed
- Heat recovery fans in bathroom and kitchen
- Water saving : dual-flush toilets, flow aerators/restrictors, water butt
Our aim has been to reduce the carbon footprint of the house. This led us to make changes to reduce our electricity consumption, while generating low carbon electricity with solar photovoltaics. This meant that by 2013 we were generating 50% more electricity than we needed to run the house appliances. In order to reduce the carbon footprint from gas consumption we started with solar water heating then moved on to major improvements to insulation and draught proofing, helping to reduce our space heating carbon emissions. As the carbon intensity of electricity has fallen rapidly in recent years it has become efficient to replace a gas boiler with an electric heat pump and this is our most recent improvement.
In retrospect the whole process could have been carried out more logically, with much less disruption and dirt. But we learned on the job and have only come to understand a better way to proceed with hindsight.
Along the way we have also learnt to improve our energy use (at no extra cost!) so that, over a 15 year period we estimate our annual domestic energy CO2 production has reduced from 10 tonne/year to less than 0.3 tonne/year for this two-person household.
Our house dates from the 1880s. It is a small mid-terrace in a Conservation Area. The original house has solid external walls and there is a single storey 1960’s extension with cavity walls. The total floor area is 78 sq. m.
The process began with the installation of photovoltaic panels in 2005. This encouraged us to start reducing electricity consumption by choosing low energy lighting, replacing failed appliances with energy efficient equivalents and generally remembering to switch things off. Solar water heating followed in 2007 and then we started to tackle insulation including suspended and solid floors; insulation of external walls with internal aerogel; draught reduction and mechanical heat recovery ventilation; triple glazed windows. So, the estimated overall 95% carbon reduction has been due to many small changes.Benefits:
As well as having much reduced energy costs we also have a more comfortable, draught free home, with heating thermostats set at 19 rather than 21o C It was a great feeling when we managed to reduce our annual electricity consumption to less than our annual PV generation so we had become a power station, exporting more to the grid than we imported.Favourite Feature:
Currently the new Air source heat pump but we don’t have any performance figures yet. Watch this space….