An Update of a Simulation Study of Passively Heated Residential Buildings

Abstract

“A simulation study of passively heated residential buildings” published in Procedia Engineering 2015 showed how circulating 15-17°C water from a 50-m deep U-tube to a floor radiator and solar-heated water from a 30 evacuated tube solar collector and a 2-m3 indoor tank to a wall radiator could keep a 30-m2 Melbourne, Australia house thermally comfortable. This paper presents a summary of the ongoing review of publications together with three updates: - (1) Report on that water heated by a 100-metre deep U-tube is 22-24°C, i.e., 2-4 °C warmer than thermal comfort temperature. (2) May 2016 experimental validations of the simulated results which show that when the outdoors is below 10°C, the temperature of the floor radiator is 2-4°C less than the 15-17°C water heated by a 50-m deep U-tube and 25 W fish tank pumps could circulate the waters. (3) Simulations with the addition of phase change materials (PCM) to inside faces show that though a PCM halves the diurnal indoor temperature variations, it confirms that such PCM does not significantly increase the 20°C temperature in a 2-m3 storage tank at the end of winter. Therefore, the size of intersessional thermal storage would be a problem for family-sized houses. German Guidelines indicate that 1-2 boreholes could provide enough heat for family-sized houses. The heat extracted in winter can be replenished in summer. Thus the geothermal heat from about 100-m deep boreholes with 22-24°C bottom temperature could sustainably keep residential buildings in cool climates similar to Melbourne's cool temperate thermally comfortable.

Keywords

• Hydronic radiators
• geothermally-heated water
• sustainable residential buildings
• cool climates