It’s possible in Ecotect to look very quickly at shadowing and to calculate the effects of changes to windows meaning that variations in the location, size, and properties, can be quickly compared. We wanted the house to be very light because it’s pleasant and you use less electricity on lighting. This meant having a roof light in the Kitchen, and a strip of rooflights running the length of the extension. The modeling showed that these are far enough away from the shadow of the main roof to get direct sunlight all year.
The existing Conservatory on the South West face acts as a buffer space to the Sitting room, reducing heat loss through the adjoining wall and at times contributing heat. We will eventually, when we have the money, renew this structure and intend adding Solar PV Glass to the roof. This will bring us much closer to producing the electricity that we need on site. Of course we’ll still need the national Grid as our storage system.
We chose an efficient heat source, distribution system, and controls. We wanted to be using renewable energy, which eliminates gas. We’re on the highest point of the South Wales coast and there’s plenty of wind, but battling to get consent for a large’ish wind turbine in an urban setting is a waste of time. Biofuel might have been possible but less convenient than the Electricity we decided on. Conventional electric heating would be too expensive to run, but a Heat Pump can be very cost-effective if it has a good CoP. As many will know the smaller the difference between the flow and return temperatures the more efficient a Heat pump will be. So the larger the area over which heat can be distributed the lower the flow temperature needs to be. A heat pump allied with underfloor heating can be very efficient and cost-effective.
After discussion with Radiant Heating we chose an Air Source Heat Pump. We’re very near the sea, and have higher than average temperatures, the grounds very hard ground with a very thin layer of top soil, it costs less than a Ground Source heat Pump, and I also liked having the pump visible from the road because I want people to see that it works.
Underfloor heating in the extension was easy since we were building from new, but in the existing house I’d decided not to pull up the existing ground floors because of the terrazzo and parquet, and the existing first floor is concrete. We didn’t want to reduce the ceiling heights, raise all the door lintels, and redo all the skirting by laying another 70mm of screed over the top. How would you deal with the top of the staircase?
The answer has been to install the heating pipework vertically. The house is like a cube with two walls inside forming a cross which passes through each room. The existing plaster on these walls was all stripped off, the pipes fitted, and the whole lot rendered over with a lime/hydraulic lime mix in two layers to a depth of 30mm, which was then plastered. We have a manifold in the Utility room on the ground floor, and another in the Attic covered in 200mm of glass fibre insulation, (there just wasn’t room on the first floor). Of course we have to be very careful when making holes for hanging paintings. I bought a Bosch Sensor that indicates where the pipes are and I use a screw driver rather than a hammer drill to make the holes.
Each room has a separate circuit on the manifold allowing them to be individually controlled by programmable radio thermostats. These are set to provide heating and keep the living spaces at a uniform 19°C, (the system could also provide cooling if we wanted). The combination of the high thermal mass of the house and low infiltration means that temperature changes are slow, allowing the occupants time to adapt to changes in temperature and reducing their perception of cold or overheating. The Ecotect modeling also showed that a constant temperature uses less energy than the more usual stop-start of heating only in the morning and evening.
Other electrical load is all as low energy as we can make it, with only LED lighting, A+ appliances, and an electric cooker with Induction hob.
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