16. The Energy Conservation Potential of Using Phase-Change Materials as Thermal Mass Material for Air Source Heat Pump-Driven Underfloor Heating System in a Building

Improved energy efficiency in buildings is the key element to reduce the greenhouse gas emissions while contributing to energy security. Underfloor heating is a more efficient and economical method for home heating with improved thermal comfort than any other heating methods. Due to the low-temperature heating source requirement the underfloor heating is widely accepted as the most efficient form of heating. Heat pumps are energy-efficient equipment to provide low-temperature heat source which is suitable for underfloor heating applications. Phase-change materials (PCMs) are attractive for use in thermal energy store for underfloor heating applications due to their high-energy storage density over a small temperature range, therefore allowing the air source heat pump to operate during winter warmer afternoon ambient air conditions or in an electricity tariff management mode. A numerical simulation model has been validated and used to analyse the thermal performance of PCM-layered underfloor heating under different heating modes. Different layouts of the underfloor heating pipes with PCMs as floor mass material were analysed for realistic diurnal temperature boundary conditions and temperature distribution was predicted.