- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 16 Nov 2020
Phase change in buildings
When systems change phase, they absorb or release significant amounts of heat energy (latent heat, expressed in J/kg). The systems themselves do not change temperature as the energy is consumed or generated by the physical process of changing the state of the system. For example, when water evaporates, it absorbs heat, producing a cooling effect. So when water evaporates from the surface of a building, or when sweat evaporates from the skin, this has a cooling effect. Conversely, when water condenses it releases heat.
Phase change is also important in refrigeration, where refrigerant gases absorb heat from the cooling medium (typically water) as they evaporate, and release heat when they condense, which is rejected to the outside (or recovered). The exact opposite of this process is used to generate heat in heat pumps.
A newly-emerging application of phase change in buildings is the use of phase change materials (PCM). These are generally materials with a large specific latent heat capacity. They can be used in construction to reduce internal temperature changes by storing latent heat in the solid-liquid or liquid-gas phase change of a material. Heat is absorbed and released almost isothermally and is used to reduce the energy consumed by conventional heating and cooling systems by reducing peak loads.
Phase change materials used in buildings will typically melt and solidify within a range of 18-30ºC. They are able to store up to 14 times more thermal energy per unit volume than conventional thermal storage materials.
 Related articles on Designing Buildings Wiki
- Advanced phase change materials.
- Advanced phase change materials industry.
- Heat transfer.
- Thermal comfort.
- Thermal mass.
- Building services.
- Gross calorific value.
- Latent heat.
- Mass transfer.
- Phase change materials.
- Solar gain.
- Thermal optical properties.
- Thermal mass.
Featured articles and news
The story behind the copycat architecture craze.
Insight into construction materials supply and demand issues.
IHBC has announced winners of the 2020 honours.
Cement and concrete industry introduces measures to go beyond net zero.
UKGBC has introduced a resource to help with sustainability challenges.
Is it time to embrace EVs at last?
Plaster, glue and dye produce a highly decorative effect.
BSRIA predicts winners and losers for 2021 and beyond.
Firms must commit to net zero to secure major public work.
The resurgence of the British country house. Book review.
International Energy Agency report presents narrow path.
Experts discuss how the country's ageing housing stock can meet net zero goals.
This form of drainage may be a practical plumbing option.
The Government announces additional funding.