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- Buildings need fresh air, but exhausting conditioned indoor air and bringing in untreated outdoor air can waste a large share of heating and cooling energy. In cold weather the incoming air must be heated; in hot weather it must be cooled. Air-to-air heat recovery closes that gap.
- An air-to-air heat exchanger transfers energy between the outgoing exhaust stream and the incoming supply stream without mixing the two airstreams. Sensible recovery moves heat only; enthalpy, or total, recovery also moves moisture, which is valuable in humid climates.
- Plate exchangers: stationary aluminium or polymer cores, simple and reliable, good when the two streams must stay fully separated. Rotary wheels: a spinning desiccant-coated wheel that stores and releases heat and moisture; high efficiency but with some cross-leakage between streams.
- Recovery is most valuable in buildings with high air-change rates: schools, offices, hospitals, and labs. In cold climates, recovering heat from exhaust can cut heating demand by a third or more.
- Match effectiveness to climate: higher in cold regions, balanced against fan energy. Use bypass dampers in shoulder seasons so free cooling is not blocked. Specify frost protection, such as preheat or exhaust recirculation, for very cold sites. Keep filters clean; fouling is the main cause of lost performance.
- For most ventilated buildings, air-to-air recovery is one of the shortest-payback energy upgrades available. The hardware is mature, maintenance is low, and the savings recur every heating and cooling season.
Buildings need fresh air, but exhausting conditioned indoor air and bringing in untreated outdoor air can waste a large share of heating and cooling energy. In cold weather the incoming air must be heated; in hot weather it must be cooled. Air-to-air heat recovery closes that gap.
An air-to-air heat exchanger transfers energy between the outgoing exhaust stream and the incoming supply stream without mixing the two airstreams. Sensible recovery moves heat only; enthalpy, or total, recovery also moves moisture, which is valuable in humid climates.
- Plate exchangers: stationary aluminium or polymer cores, simple and reliable, good when the two streams must stay fully separated.
- Rotary wheels: a spinning desiccant-coated wheel that stores and releases heat and moisture; high efficiency but with some cross-leakage between streams.
Recovery is most valuable in buildings with high air-change rates: schools, offices, hospitals, and labs. In cold climates, recovering heat from exhaust can cut heating demand by a third or more.
- Match effectiveness to climate: higher in cold regions, balanced against fan energy.
- Use bypass dampers in shoulder seasons so free cooling is not blocked.
- Specify frost protection, such as preheat or exhaust recirculation, for very cold sites.
- Keep filters clean; fouling is the main cause of lost performance.
For most ventilated buildings, air-to-air recovery is one of the shortest-payback energy upgrades available. The hardware is mature, maintenance is low, and the savings recur every heating and cooling season.
