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Last edited 30 Jul 2021
Building heating systems
- Create comfortable conditions for occupants.
- To prevent condensation.
- For activities such as drying and cooking.
- For industrial processes.
- Solid fuel – timber, coal, peat, biomass.
- Liquid – oil, liquid petroleum gas (LPG).
- Gas - natural gas, biogas.
- Electricity - grid, wind turbines, hydroelectricity, photovoltaics.
- Water – solar thermal, geothermal, ground source, water source.
- Air source.
- Heat recovery.
- Passive – solar gain, thermal mass.
- Internal heat loads - heat generated by people and equipment.
- Solid fuel burners.
- Combined heat and power (CHP) plant.
- Electrical heaters.
- Gas heaters.
- Heat pumps.
Heat generators can be local to the demand for heat, or can be centralised and distributed, either within a single building or on a wider basis as part of a district heating network. Heat distribution can be by:
- Air blown through ducts, plenums or occupied spaces.
- Water pumped through pipework.
- Steam distributed through pipework.
- Passive air movement.
- Passive diffusion of heat through thermal mass.
Heat transfer mechanisms include:
- Locally by manual or automated thermostats, switches or dampers.
- Centrally by manual or automated thermostats, switches or dampers.
- Building management systems.
Heating control systems often require re-evaluation once buildings are completed and occupied. Systems may require fine-tuning as internal heat loads and occupant behaviour do not always conform with design expectations. Occupant training can be helpful to optimise the performance of heating systems, and occupants can be appreciative of a degree of local control.
 Optimum temperatures
The human thermal environment is not straight forward and cannot be expressed in degrees. Nor can it be satisfactorily defined by acceptable temperature ranges. It is a personal experience dependent on a great number of criteria and can be different from one person to another within the same space.
There is no legal requirement to achieve a minimum or maximum temperature within a building. The building regulations Part J, Part L and Part F set out requirements for safety, the provision of information, the consumption of energy, standards of construction, carbon emissions and ventilation requirements, but they do not prescribe temperatures.
The Health and Safety Executive suggest that an environment can be said to achieve ‘reasonable comfort’ when at least 80% of its occupants are thermally comfortable. This means that thermal comfort can be assessed by surveying occupants to find out whether they are dissatisfied with their thermal environment.
The Workplace (Health, Safety and Welfare) Regulations simply state that, ‘during working hours, the temperature in all workplaces inside buildings shall be reasonable’, however, the associated approved code of practice Workplace health, safety and welfare. Workplace (Health, Safety and Welfare) Regulations 1992. Approved Code of Practice suggests:
'The temperature in workrooms should normally be at least 16 degrees Celsius unless much of the work involves severe physical effort in which case the temperature should be at least 13 degrees Celsius. These temperatures may not, however, ensure reasonable comfort, depending on other factors such as air movement and relative humidity.’
There are no legal restrictions to maximum temperatures, however there is strict regulation of heat stress. Previous guidance by the HSE suggested that thermal comfort might be achieved between 13 and 30°C depending on the activity of occupants.
Operators of shared heating systems are subject to the Heat Network (Metering & Billing) Regulations 2014. The Regulations apply to systems in which water is heated or chilled at a central source of production before being piped to multiple buildings (district networks) or multiple customers in a single building (communal networks).
Heat suppliers are required to register their heat networks with the Office for Product Safety & Standards and, in the case of unmetered networks, may be required to install meters measuring customers’ actual consumption of heat. Where such meters are installed, heat suppliers are required to use them to bill customers according to their actual consumption.
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- Scotland publishes plans to reach net zero targets with Heat in Buildings Strategy.
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