A debate that appears to be much talked about is the pros and cons of airtight buildings and their ventilation systems.
Simply, there are two ways in which to ventilate a building, mechanical or natural (sometimes called passive). The arguments are spilt as between those who favour the measurability in energy terms of the power consumption of the mechanical systems and how this can be accounted for in energy modelling software, and the other side who prefer the natural adaptability of humans to regulate their environments, e.g. by opening windows, putting on more clothes, adjusting blinds, etc.
On the mechanical side, it is easy to see how at the modelling stage of a building’s predicted energy consumption in usage, the data can be inputted to account for the energy consumption of the fans, heat exchangers etc. What these models cannot account for is the human behaviour element. Indeed there have been tales of Passivhaus (a highly insulated, airtight, low energy design) owners wives opening the windows to allow the fresh air in!
In an article published in this month’s Green Building magazine, Professor Sue Roaf comments on the subject of adaptability and human comfort. She notes that the perception of pleasure is greatest when our environments are in a constant state of flux, i.e. not at a static temperature and air movement level, as is the case in mechanically ventilated buildings. Most pleasure is derived from the feeling of being warmed up when cold, and conversely cooled when too hot. This is the body reacting to uncomfortable conditions and producing behaviours to return it to balance, in other words, the human element of how we live in and use or buildings. Perhaps with the increased collection of post occupancy data gathered from real houses with people in and not theoretical models we may be able to factor these behaviours in, though I suspect this is a long way off.
Part 2 : Next bog entry will take this subject further and look its relation to embodied energy in buildings. Watch this space for further exploration of this wonderfully complex issue of everyday living.
 ‘Exactly how comfortably are you sitting’ Green Building Magazine Volume 22, Green Building Press (2012)