'A Lifecycle Analysis Examining the role of Thermal Mass'.
Mike George
posted on 28-10-06
Hi all, does anyone know if the ARUP report referred to in the latest BFF is freely available for download?
Tony
posted on 28-10-06
Try googling for it I found plenty I liked as it says that thermal mass improves the efficiency of both heating and cooling systems. The research was funded by concrete people though. In longer term analysis its findings segest that heavy will give rise to less CO2 than light weight construction. And so they say timber frame is less eco friendly than heavy.
Mike George
posted on 28-10-06
Thanks Tony, It doesn't seem like the full report is availble from the concrete association or Arup's yet though. I wanted to read the complete report as I'm sure the devil is in the detail.
mark brinkley
posted on 29-10-06
I have only read an article about the report, rather than the report itself. I can't help feeling that as a piece of research it is fatally flawed. Firstly, it was funded by the Concrete Centre, who are hardly impartial in such matters. Secondly, they set the frame of reference for the modelling. Crucially, they asked Arup to look at the heating and cooling load of a house in PERMANENT occupation (ie 24/7). This puts high mass housing in a much better light. A house where the residents leave for work at 7 or 8 and don't return till 6 or 7 is unlikely to benefit from the heat stored in the structure, nor for that matter from the summer cooling effect.
Tony
posted on 29-10-06
The last part is not at all true Mark. The more any solar energy gained during the day can be storred in the house for free the lower the heating bills will be and if it is a very hot summer the house will not suffer from overheating either.
mark brinkley
posted on 29-10-06
That's pretty much what the eminent report says. And its true, so long as the house is in continual occupation. But there is a downside to high thermal mass too which is often ignored. You have to put a lot more energy into heating up the house fabric. Some of this can be passive solar but only about 30%. The rest has to be derived from fossil fuels. Now if the house is constantly occupied, you get full benefit of the passive solar, but if the house is empty for lengthy periods then much of that stored heat is wasted. Its even worse if the house gets left empty for a week in the winter, when 500kWh or so of thermal stored heat is lost without anybody deriving any advanatge at all.
Exactly the same thing happens in summer. High mass homes are demonstrably cooler duing the dayttime in heatwaves. But that only makes a difference if the building is occupied. At night, they are actually hotter than low mass homes and may well make it harder to sleep comfortably.
