Friday, February 11, 2011

Mark Brinkley's Blog - Denby Dale

1102-2011 : Mark Brinkley is author of Housebuilder's Bible, and writes a lively blog on house construction and energy issues, Home 2.0. I advise readers to view this occasionally.
   He has earlier promoted the Denby Dale passivhaus, and recently wrote an article on how Denby Dale passivhaus had weathered the Dec 2010 month. They have done well, although it draws two things to my attention.

 1. They have an efficient gas boiler, but also use gas for cooking and DHW, so they have difficulty knowing exactly what gas is used specifically for heating. This could be solved by getting a gas plumber to fit a meter to the pipe that feeds the boiler, so they can at least remove the variable of Cooking. It is also possible to fit a water meter on the Hot water pipe so that it can be measured, as we do at Peveril.

 2. There is a different calorific value for Gas and Electricity - what really matters in the end is the amount of CO2 this is equivalent to. Electricity means burning fuel in a power station somewhere else, and transmitting 30 miles, whereas gas is piped to your house and burnt at home. Hence the difference in Cost of the two fuels and the difference in CO2 equivalent. I wrote more about this in December:

I am glad to see that the Govt redefined the 2016 standard in kilograms of CO2, not in kWh, as that makes it easier to calculate the real energy cost.

For December 2010, here, our GSHP used 768 kWh, but if you take away the consumption of the floor circulating pump and the DHW, that is about 645 kWh for the month, for space heating. Our PV is always bad in December due to the large hill to the SE of the house, so we have to drink heavily from the grid during December. Despite this, and with the help of 109 kWh from the sunboxes, the deep ground temperature managed to stay just above 10ยบ by New Year's Eve.
 For our 120 sqm house, 645 kwh is about 5.4 kWh/m2/year or 2.9 kg of CO2/m2/year, which is about right as December was about 1/5 of the entire degree days for 2010.

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