Architects accrue a wide variety of knowledge over years of training and professional practice, and I think we sometimes take for granted our understanding of passive design principles. I came across this Australian Government website recently which includes lots of useful information and explains the principles of passive design in some detail for those who are unfamiliar with them.
Thermal mass is something I’ve discussed with a clients recently, as it seems where to use it doesn’t seem to be well understood. I’ll use the house I currently live in to illustrate a point. It has a concrete slab on ground with a floating timber floor. One of the living spaces receives fantastic morning sunlight through until about midday. During the cool autumn mornings the space is nice and warm and heating isn’t required. But once the direct sunlight is lost in the early afternoon, the space quickly loses warmth, and the timber floor feels cold. If the concrete slab was exposed or even had a tiled finish, this would provide thermal mass would store the heat and re-radiate it during the afternoon and evening. It would significantly smooth out the dramatic temperature fluctuations.
In contrast to this, we have a second living space which doesn’t receive much sunlight at all. In this situation having an exposed concrete slab (or tiles) would actually work against maintaining a comfortable temperature, as the concrete would absorb the cold and stay cold all day. For the sake of my passive design argument, artificial heating hasn’t been taken into consideration.