- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 19 Jan 2016
Heat recovery ventilation
To help develop this article, click 'Edit this article' above.
- Moderate internal temperatures.
- Reduce the accumulation of moisture, odours and other gases that can build up during occupied periods.
- Create air movement which improves the comfort of occupants.
Very broadly, ventilation can be ‘natural’ or ‘mechanical’.
- Mechanical (or ‘forced’) ventilation tends to be driven by fans.
- Natural ventilation is driven by ‘natural’ pressure differences from one part of the building to another.
Ventilation has become increasingly important because of the tendency to ‘seal’ modern buildings. However the process of extracting internal air, which may have been conditioned, and replacing it with air that has not is inherently wasteful.
This can be mitigated by heat recovery, the process of collecting and re-using heat that would otherwise be lost, which can help to reduce energy consumption, reducing running costs and carbon emissions.
Heat recovery ventilation (HRV or ventilation heat recovery (VHR) or mechanical ventilation heat recovery (MVHR)) uses a heat exchanger to recover heat from extract air, that would otherwise be rejected to the outside, and uses this heat to pre-heat the ‘fresh’ supply air. Very efficient heat exchangers can recover as much as 98% of the ‘waste’ heat.
Typically heat recovery ventilation works by transferring heat between the incoming and outgoing air streams by blowing them in opposite directions between adjacent flat plates in air-to-air heat exchangers. Heat is absorbed by the plates from the 'hot' air on one side and released to the 'cold' air on the other. Cellular heat exchangers, which can achieve greater efficiency, drive the incoming and outgoing heat through adjacent square tubes, increasing the heat transfer surface area.
Heat can also be recovered from other processes and components, such as refrigeration units and chiller units, boilers, power generation plant, plant cooling systems, hot liquid effluents and high-temperature exhaust gasses. Recovered heat can also be used for drying processes, power generation, pre-heating combustion air for furnaces or boilers and so on.
 Find out more
 Related articles on Designing Buildings Wiki.
- Air conditioning.
- Air handling unit.
- Chiller unit.
- District energy.
- Geothermal pile foundations.
- Heat pump.
- Heat recovery.
- Mechanical ventilation.
- Thermal labyrinths.
- Variable refrigerant flow.
 External references
- Heat recovery: A guide to key systems and applications.
- How to implement heat recovery in heating, air conditioning and ventilation systems.
- The Future of Heating: Meeting the Challenge.
- The potential for recovering and using surplus heat from industry.
- Harvesting energy: body heat to warm buildings
Featured articles and news
Modern slavery in the construction sector.
What to bear in mind when claiming damages in construction.
How do we achieve sustainable clean-water infrastructure for all?
What you should know when appointing an architect.
A brief history plus some new developments.
How computational fluid dynamics (CFD) helps building design.
The Hong Kong Harbour Area Treatment Scheme (HATS).
'Expressions of interest' for construction contracts.
Dame Judith Hackitt confirmed as keynote speaker – one year on from the Hackitt Report. Save £100 on tickets.