# Air conditioning and ventilation in a commercial EPC upgrade > Why ventilation cannot simply be reduced, where heat recovery and demand control earn their money, and how cooling interacts with lighting and glazing. Source: https://commercialepcupgrades.co.uk/measures/air-conditioning-and-ventilation --- # Air conditioning and ventilation in a commercial EPC upgrade Most measures on this site reduce a load. Ventilation is different: the building has to supply fresh air for the people in it, and that quantity is not negotiable downwards for energy reasons. So the measure is not using less air, it is stopping the heat in that air walking out of the building with it. Middling cost, and it is where lighting savings show up twice ## Heat recovery is the main event Air leaving a building in winter is warm and has been paid for. A heat recovery unit transfers that warmth to the incoming air, so the building spends far less bringing fresh air up to temperature. In a building with mechanical ventilation and no recovery, this is frequently the largest single available saving after lighting. It is also a plant decision rather than a quick fix, so it tends to arrive with a plant replacement or a refurbishment. ## Demand control: the right amount of air, when it is needed A ventilation system set for full design occupancy runs at full design occupancy all day, whether the building is full or has four people in it. Demand-controlled ventilation modulates against actual occupancy, usually sensed by carbon dioxide level. That is a controls retrofit rather than a plant replacement, and in a building with variable occupancy, meeting rooms, or hybrid working patterns, it is one of the better value measures available. - Carbon dioxide sensing in meeting rooms and open plan, which are the spaces with the most variable load. - Time scheduling matched to real occupancy rather than lease hours. - Making sure the system is actually off when the building is empty, which is an embarrassingly common finding. ## Cooling, lighting and the hidden second saving Every watt of lighting in an air-conditioned space is a watt the cooling system has to remove in summer. Reducing lighting load therefore reduces cooling load, which is a real saving that almost never appears in a lighting quote and is worth asking about. The same is true of IT and equipment load. In a cooled building, anything that reduces internal heat gain pays twice. ## Refrigerant is a separate question Older cooling plant may use refrigerants being phased down, which affects the cost and availability of servicing rather than the energy performance directly. It is worth knowing the position for the plant in your building before committing to repair rather than replace, because it can change which is the economic choice. This is a question for a qualified refrigeration engineer, not something to resolve from a web page. ## Questions we get asked ### Can we just ventilate less to save energy? ### What is demand-controlled ventilation? ### Does changing the lighting reduce cooling costs? Sources - A non-domestic EPC is an asset rating: it is based on the fabric of the building and its services rather than on metered consumption. [A guide to energy performance certificates for the construction, sale and let of non-dwellings, DCLG, 2014](https://www.gov.uk/government/publications/energy-performance-certificates-for-the-construction-sale-and-let-of-non-dwellings) Last updated 8 October 2026 . - [Building management systems What runs the ventilation](https://commercialepcupgrades.co.uk/measures/building-management-systems) - [Lighting Where the second, cooling-side saving comes from](https://commercialepcupgrades.co.uk/measures/lighting) - [Pool halls Where ventilation dominates everything](https://commercialepcupgrades.co.uk/buildings/gym-and-leisure) Next step ## Get air conditioning and ventilation priced for your building Tell us the building type, the floor area and the rating you are on now. One commercial contractor comes back to you with a quote off a survey. Or call [07367 293494](tel:+447367293494). Monday to Friday, 9am to 5.30pm.