An exhaust air heat pump (EAHP) can provide cooling, but it depends on the type of unit and how the system is designed.

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How it works

An EAHP extracts heat from warm, stale exhaust air from spaces such as bathrooms, kitchens and utility rooms. In heating mode, this heat is transferred to water for:

• Space heating

• Domestic hot water (DHW)

If the heat pump is reversible, the refrigeration cycle can be reversed to provide cooling.

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However, there is an important limitation

The cooling capacity of an EAHP is generally limited by the amount of exhaust air available.

For example, if a dwelling has only 200–300 L/s of extract air, there is a limited amount of heat that can be rejected/extracted from that air. Therefore, an EAHP may provide useful cooling, but it may not be sufficient to meet the complete cooling load of a building.

A typical arrangement might be:

Rooms → extract grilles → EAHP → heat recovery/refrigeration cycle → outside

For cooling, the system can provide chilled water to:

• Fan coil units (FCUs)

• Underfloor cooling

• Chilled beams

• Other suitable terminal units

 

One important distinction

Don't confuse an EAHP with an air-source heat pump (ASHP).

 

Can the following systems provide cooling?

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Exhaust Air Heat Pump Extract/stale indoor air. Yes, if reversible

Air Source Heat PumpOutdoor air. Yes, commonly

Ground Source Heat Pump Ground. Yes, with suitable system

MVHR Exhaust air heat recovery.  Normally no active cooling

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In practice: if your objective is heating + DHW + cooling, an EAHP can be designed to do all three, but the ventilation airflow and cooling load need to be checked carefully. For larger or heavily cooled buildings, an ASHP or a combined EAHP/ASHP arrangement may be more appropriate.​​