Produced in Association with


SERIES 23 / Module 07 Cooling Buildings


system can also be used to pre-cool air for a conventional HVAC setup. ● Open or closed loop water-to- air heat exchanger: This exploits the relatively stable temperature of the earth to provide water that can cool in the summer and heat in the winter. There are also devices that do not


in themselves provide cooling but reduce a building’s thermal gains and correspondingly cooling load. They include shading solutions like Brise soleil which are external shading structures fitted over the entire exterior of a building or solely over the windows. They can range from simple lattices or patterned concrete structures, to mechanical baffles controlling year- round solar radiation, and helping to reduce glare. BRE 364 Solar Shading of Buildings is a useful reference. ● Green roofs: They provide a


canopy that reduces heat coming through the roof as additional thickness of the growing medium provides extra thermal insulation. They moderate the heat flowing through the roof, which helps to reduce temperature fluctuations caused by solar radiation. The green cover also retains moisture from rainwater which further cools the roof surface via transpiration. Green roofs can also reduce the problem of urban heat island. Heat-reflective glass or the


application of anti-glare film can help prevent heat build-up. By applying solar-reflective film to windows, the ‘greenhouse effect’ can be mitigated, reducing solar heat gain by up to 60%. Passive cooling features may


increase a building’s upfront embodied carbon, but these increases are offset by the reduced need for cooling plant and lower lifetime operational emissions, resulting in improved whole-life carbon outcomes. Traditional cooling load reduction strategies and the implementation of passive cooling could slow the growth in cooling demand by 24% by 2050, reducing CO₂-equivalent emissions by 1.3 billion tonnes².


Active cooling Active cooling makes use of mechanical, or forced, ventilation, driven by fans and refrigerant systems. Active cooling might be provided as part of a heating, ventilation and air conditioning system (HVAC) which may also include air filtration and humidity control. ● Chilled beams: These are a type of partially centralised system; they


Produced in Association with Brise soleil can control year-round solar radiation and help reduce glare


consist of ceiling-mounted panels of pipes cooled by chilled water. They transfer their cooling effect to the space by radiation, natural convection, or minimal fans to encourage air movement. They operate with higher chilled water temperatures (typically 14°C to 17°C) requiring less energy compared to traditional systems. Passive Chilled Beams (PCB) rely


solely on natural convection, where warm air rises to the ceiling, passes through the chilled beam, cools, becomes denser, and falls back down. Active Chilled Beams (ACB) on the other hand connect to a ventilation system, with air from an AHU passing through nozzles, inducing room air movements. ● Air conditioning systems: Typical


air conditioning systems comprise compressor, condenser, evaporator coil, blower/fan and refrigerant. There are several types of air conditioning systems: Local systems are used to serve a


single zone or small proportion of a building, usually cooling the immediate space where they are located. They provide comfort cooling or serve areas which have a different cooling schedule to the rest of the building, e.g. IT rooms. Split unit air conditioning systems


are the most common type of local systems, where a single indoor cassette is linked to an outdoor condenser. Monobloc or packaged air conditioning units deliver air cooling from a single unit (casing), inclusive of a condenser within the same casing.


They are useful where there is limited room for an external condenser. They are increasingly used for installation in smaller rooms or office spaces. ● Centralised systems are based


around a packaged air handling unit (AHU) which typically contains heating and cooling coils, a filter, fans and sometimes a dehumidifier. The incoming fresh air is drawn into the AHU and passed over the coils to cool the air as required. This ‘conditioned’ air is then supplied by ductwork to the zones/ rooms within the building usually via constant volume or variable air volume systems. Constant volume (CV) single zone


systems are simple, low cost and easy to commission, but cannot provide adequate control for areas or ‘zones’ with different/simultaneous heating or cooling needs.


Variable air volume (VAV) systems


address the problem of zones with different requirements by varying the quantity of air (and hence the amount of cooling) supplied to each space. VAV systems can be particularly energy efficient as they are able to operate the main supply and extract fans at reduced speeds. Variable refrigerant flow (VRF)


systems are where refrigerant is the only coolant material in the system (contrary to chilled water systems). They comprise an outdoor unit (one or multiple compressors), multiple indoor units serving different areas/ rooms, and refrigerant piping running from outdoor to indoor units. Fan coil units (FCU) are partially


centralised systems which typically comprise a fan and heating and cooling coils, all housed in a metal casing. The fan draws air into the unit and blows it over a cooling coil supplied with chilled water from a central plant. ● Absorption chillers use heat to


drive the refrigeration cycle. They produce chilled water while consuming just a small amount of electricity to run the pumps on the unit. Whereas regular compression cooling depends on electricity, absorption cooling can run on various heat sources. They are now a feature in city centre locations where electrical capacity is constrained. Cooling systems efficiency is


defined in terms of Energy Efficiency Ratio (EER). For chillers it is the ratio of the cooling energy delivered into the cooling system divided by the energy input to the cooling plant. For packaged air conditioners, the EER is the ratio of the energy removed from air within the conditioned space divided by the effective energy input to the units. In view of part load conditions across


a year, systems efficiency is based on seasonal energy efficiency ratio (SEER) which is the ratio of the total amount of cooling energy provided divided by the total energy input to the cooling plant (which may comprise more than one cooling unit), summed over the year and recognising part load conditions. Air conditioning systems use HFC


A monobloc or packaged AC unit delivers complete air cooling from a single casing


refrigerants like R-404A, R-134a, and R-410A with high GWP potential (GWP >1,500) cause significant global warming if released. New installations should seek to incorporate lower impact refrigerant like R290 (GWP of 3). Low GWP refrigerants, together with energy efficient equipment are key to decarbonisation in the cooling sector. Solid state cooling: There are


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EIBI | FEBRUARY 2026


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