Air and Ground Source Heat Pumps

Heat pumps are a low-carbon heating technology. While they provide much cleaner heat than traditional gas boilers and, once installed, they are typically much more energy efficient than electric heating. Heat pumps works by capturing latent heat from the environment and converting it into useful thermal energy to provide heating and hot water. There are two main types, named for where they derive their heat from: air source and ground source.

The efficiency of a heat pump is governed to some degree by the ‘source’ temperature it is drawing from, making it less efficient at heating up a building when the outside air or ground temperature is lower. However, most air source heat pumps are able to draw sufficient latent heat to provide heating even if temperatures drop as low as –5C. Even at –15C, many air source heat pumps will continue to generate some heat.

Ground source heat pumps (which draw from the ground) are more consistent in that underground temperatures rarely deviate drastically like air temperatures can, typically staying above 5C all year round. While air source heat pumps are generally better at providing heating and hot water when outside temperatures are higher, ground source heat is more efficient when it comes to providing heating when outside temperatures drop.

As ground source heat requires boreholes to be installed to allow it to access ground heat, air source heat pumps are typically cheaper to install, but less efficient overall than ground source. This greater efficiency typically means that despite higher upfront costs, ground source heat delivers better long-term savings.