Housing energy is nearly a third of total energy and is by far the biggest slice of UK household energy use. To make serious inroads in cutting CO² from housing, reducing heating energy has to be part of any solution. Effective and efficient heating systems are essential to reduce the total heat demand. Recently low temperature air source heat pumps are becoming popular. They are categorized as renewable energy technology and can be used to further reduce carbon emission. Hydronic heat emitters are commonly used in domestic heating in EU houses and their performance has a strong influence on energy consumption and human comfort. In this study, an in-house environmental chamber was built for evaluating the performance of emitters from different perspectives such as heating up speed, temperature uniformity, air velocity distribution and human comfort. This work will give important figures for comparing emitter performance from the indoor environmental comfort point of view and it indicates the optimization possibilities for future product design.