Radiant heating with reduced indoor temperature
In a room with radiant heating, the same comfort is perceived at a lower temperature than in a room with convective heating. Due to the smaller temperature difference between inside and outside, each degree lower room air temperature decreases the heating demand by approximately 6 per cent (assuming that the radiant heating surfaces are not located on exterior walls). However, the savings decrease the more efficient the heat recovery in the ventilation system.
Heat pumps and condensing gas furnaces perform with a higher efficiency if low temperature radiant surfaces are used to distribute the heat. The COP of an earth-coupled heat pump increases about 30 per cent if the temperature of the heating system is reduced from 45°C to 35°C. The efficiency of a condensing gas furnace increases approximately 3 per cent to 5 per cent.
Savings from solar air-heated hypocaust or murocaust systems
Because high-performance houses require so little heat, it is essential to offset the investment costs of a solar air system by also using it to produce DHW. This is easily accomplished by installing a bypass to shunt the solar hot air away from the heating circuit, past an air-to-water heat exchanger. A reduction of up to 60 per cent of the energy demand for hot water heating is typical.
Was this article helpful?