There have been a number of studies on domestic overheating carried out in the Uk recently, and a lot of anecdotal evidence that new homes overheat significantly. The anecdotal evidence from clients is that it particularly affects new apartment blocks designed with communal heating systems. The design of the fabric did not take into account the considerable losses of heat from the hot water distribution systems, and this ‘spare’ heat has significantly overheated communal spaces. In some cases corridor fire doors are propped open to all for ventilation.
This does not sound good. Particularly given that we can reasonable expect warmer summers to become ‘normal’ over the lifetime of these buildings, and there are many documented cases of ‘heat death’ occurring during these warmer summers. How long will it be I wonder before some civil suit arises, blaming building designers for overheating?
The defense that will be offered is that the compliance tools in this area are woeful, inadequate and inaccurate, and that there are no effective standards governing this. Recent work by the Zero Carbon Hub on the subject demonstrates the disparity between the overheating estimates produced by SAP, PHPP and IES. In round terms the scores are PHPP (0) SAP(1) and IES and other dynamic simulation tools (5). The reality is that only a dynamic simulation package can reasonably estimate overheating because it is a problem of dynamic physics played out over time and not one of totals that can be calculated annually. The problem is that few if any of the major housebuilders consider this in their housetype design and few residential designers in the sector are familiar with this complex problem.
As we design homes to ever tighter airtightness, and focus on carbon emission savings, we are in danger of losing sight of the importance of human comfort. Overheating in such homes is a symptom of this focus and one I will come back to in the near future when I discuss our work with VELUX on their demonstration project in Kettering.