Last year, we did some house sitting in just such a place. At 6 a.m. when I got up for coffee and PhD research, the temperature in the kitchen was in the low teens C / 50 F. On sunny days it rose to 30+ C / 86+ F by late afternoon only to return to sweater weather (‘jumper weather’?) the next morning.
The role of thermal mass is to moderate these extremes – to buffer the system. It is like a bank account where an excess ‘wealth’ of heat can be ‘deposited’ on sunny days and ‘withdrawn’ at night. Think of a concrete stoop that has been sitting in the sun all day. It holds heat after sunset. Please note, thermal mass in passive solar design must be within the building envelope – that is, inside the glazing and the insulation.
Many new homes are built on insulated concrete slabs that can serve as thermal mass. This is smart design, but our 100 year-old villa is up on 1 meter piles with air flowing beneath the floor. The challenge is incorporating thermal mass inside our envelope in effective, attractive, eco-thrifty ways. The next post will explain some ways in which we plan to do this.
This picture is posted to authenticate that two real hippies were used in the making of this post. We have done our best to ensure that no hippies will be injured during the completion of this project.