The brief
Design an integrated climate control system for up to 300 people at a time, including scenarios involving classes, rest and sleep. The system must provide air supply in accordance with regulatory requirements, protected air paths with specialist filtration, energy-efficient extended operation and removal of excess heat.
The key challenge was to coordinate normal ventilation, protective modes, rotary heat recovery and central DX cooling within a single control sequence.
Solution: separate ventilation modes
The design includes several supply air systems. One group provides air supply in normal mode, while another serves the protective modes, supplying outdoor air through specialist filter elements.
This approach separates the different tasks. Everyday operation requires a steady supply of fresh air and suitable conditions for occupants. In protective mode, the airtightness of designated sections, protection of air paths and passage of air through the specified filters are also important.
Blast protection devices and airtight shut-off dampers are used in the protected air paths. They form part of an integrated solution alongside the ductwork, connection assemblies and system changeover sequence. Installing an individual valve does not, in itself, establish the protective performance of the structure as a whole.
Specialist filtration is specified to limit the ingress of contaminants in outdoor air, including radioactive and biological aerosols. The specific contaminants retained by the equipment and its application limits are defined by the design and the filters' technical documentation. Reliable operation depends on the condition of the filter elements, correct installation and adherence to the maintenance schedule.
In practice, staff need clear instructions: which mode to select, which systems must run simultaneously and under what conditions the air supply must be switched. The final control sequences are agreed for this site's specific configuration.
Rotary heat recovery for extended operation
The equipment includes an air handling unit with a rotary heat exchanger. Its purpose is to recover part of the thermal energy from extract air and reduce the load required to condition supply air. For spaces occupied for extended periods, this is a significant part of the operational solution.
Heat recovery must be considered alongside the ventilation modes. The presence of a rotor in the unit does not mean it is used in every protective mode. In these modes, the permitted level of air transfer between airstreams and the approved air supply arrangement are decisive. Heat recovery operation is coordinated separately with the requirements of each mode.
Why a basement needs cooling
Being below ground level does not eliminate heat gains from people. With 300 occupants present at once, cooling must be considered separately from fresh air supply. Ventilation provides air exchange; the cooling system removes excess heat. Increasing supply airflow is not always a sufficient or efficient way to control temperature.
Central cooling using VRF is specified for this site. Here, ‘central’ means that air is conditioned in air handling equipment and distributed through ductwork.
The VRF circuit serves a direct-expansion air cooling coil, while the AHU Kit provides the necessary coordination between the coil controls and the VRF system. Refrigerant circulates in its own circuit; conditioned air is delivered to the rooms through ductwork. The air handling unit and refrigeration circuit operate in coordination.
The system provides the required air exchange while removing excess heat from people and equipment. The design control sequence determines how cooling and protective modes operate together.
Engineering outcome
An integrated ventilation and cooling solution was developed that separates normal and protected air supply, uses specialist filtration and reduces energy demand during extended operation through rotary heat recovery.
Central DX cooling using VRF and AHU Kit removes excess heat from people and equipment. A unified control sequence defines system operation for each planned scenario and gives staff a clear procedure for switching modes.
The general principles are described on the ‘Shelter ventilation’ page. For more information on related work, see ventilation and air conditioning design, installation and building services maintenance. To begin assessing a similar brief, we need the shelter's intended design use, capacity, occupancy scenarios and existing engineering constraints.