Warm to Energy Efficient Ventilation

An innovative pre-warming system which helps ensure effective control of the internal environment has been developed by the leading natural ventilation solutions provider, Passivent Commercial Ltd.

The company’s new Thermal Aircool combines the established principles of its energy-efficient Aircool natural ventilators with an integrated low resistance air flow heater coil, purpose designed for natural ventilation systems. An ‘off-coil’ sensor within the Aircool unit monitors the temperature inside and out, allowing accurate control of the supply air temperature. In colder weather, the external air is gently pre-warmed as it enters the internal space at low level; when air temperatures inside and out are less disparate, the Aircool provides unheated air, drawing fresh external air into the building. As a result, less heating in the building is required to maintain the required internal ambient temperature, optimising occupant comfort.

The Thermal Aircool has been designed for simple installation on site. In addition, the only driving part of the Aircool is the actuator, which is sealed for life and requires no maintenance, further enhancing lifetime costings.

Wayne Aston, Passivent Director of Technical, observes, “The Thermal Aircool is primarily aimed at low level ventilation, as at high level the cooler fresh air is mixed with the warmer internal air before it comes into contact with the occupants. The system is controlled by our intelligent controller, which maximises efficiency of the entire natural ventilation system, creating a strategy which integrates seamlessly with heating systems.”

Passivent natural ventilation systems have been proven to reduce capital costs by 15%, operating costs by 40%, and almost eliminate maintenance costs, over conventional mechanical ventilation. It is also proven to reduce incidence of “sick building syndrome” and improve the performance and productivity of the building occupiers.

The Aircool units are installed in the building façade, either through the wall or window, to provide controlled fresh air intake or extract as part of a natural ventilation system, or in conjunction with mechanical cooling systems where they can reduce the need for daytime cooling and air conditioning.
Using just 1watt of electricity to attenuate the ventilation louvres, the Aircool units can be minutely adjusted to control airflow requirements taking into account the weather outside- the speed and direction of wind, rain, temperature, and the location of the units within the building façade, to ensure a gentle flow of fresh air into the building. The units can be controlled individually, or linked to an overall ventilation control or building management system to provide both effective daytime ventilation and ‘free’ night cooling.

Passivent Aircool units can be used in both new build schemes, where the ventilation strategy should be incorporated in the building design stage, and retro-fitted in refurbishment programmes. At offices in Brooklands Road in Sale, Aircool ventilators and Mistubishi air conditioning were retro-fitted, and reduced annual energy use by 41%, and ensured a comfortable internal environment not exceeding 25°C, regardless of the weather outside. At a Derbyshire school, designed to be ventilated solely by Passivent natural ventilation including Aircool units, temperature variance from one classroom to another did not exceed 1.5° from the design tolerance.

Passivent is the UK’s leading supplier of both domestic and commercial natural ventilation solutions. Part of the Building Product Design Group, the company is a founder member of the NatVent EC-EU-funded project co-ordinated by the Building Research establishment to develop practical natural ventilation solutions for the commercial sector, and has also contributed to the BISRIA Guide BG2/2005 Wind Driven Natural Ventilation Systems, as well as being a member of the DfES steering committee on natural ventilation guidance for schools, Building Bulletin 101.