Internal wall Insulation and Micro CHP 22/12/10 By Ruairi Kay
The internal wall insulation to the rear extension is now mostly complete, except the bathroom wall that needs to be left off until we seal up the existing manhole. The existing brick cavity walls have been lined internally with 70mm Celotex. We originally specified Spacetherm here like the first floor, but we changed this to Celotex to help bring the project back on budget with a minimal drop in performance. The savings is approximately £3000, over a small area of wall. On top of the Celotex we have fixed a layer of ply, to give a firm backing for the Intello plus vapour and air barrier. Then we fix timber battens to create a service void and finish this with plasterboard and skim.
Dry Lining to the rear extension.
British Gas have started to install the Baxi Ecogen Micro CHP and new wet radiator system. CHP, (combined heat and power or cogeneration) is the process of producing both electricity and useful heat from one source. Large scale CHP has been around for some time, but reliable micro domestic models are only starting to become available. The Ecogen unit produces an output of 1kW of electricity while providing 6kW of heat via a free piston Stirling engine. An addition output of 18 kW can be provided via a supplementary burner with no electricity generation. An addition output of 18 kW can be provided via a supplementary burner with no electricity generation. At the design stage we had difficulty getting estimations from Baxi as to how much electricity per year the unit would generate in this case, so in the end we used our own formula. Using our annual space and domestic hot water requirements from PHPP (PassivHaus Planning Package) and a series of assumptions on boiler operation we have come up with a figure of 698 kWh per year electricity generation. The monitoring phase of this project we will give us vital information on how the unit actually performs.
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