How was natural, passive stack and mechanical ventilation used in WISE?

Since WISE aims to be a low energy building, we have tried to limit the use of mechanical ventilation and avoid air conditioning. We have done this in several ways:

Windows for natural ventilation Natural ventilation through windows and 'casement vents'

The most simple form of natural ventilation is as simple as opening a window. However, to keep out unwanted insects and driving rain, casement vents can be used.

These are essentially a solid timber shutter with external louvres and a fly screen, which have the additional benefit of security as they can be left open over night. In WISE, this is particularly important as it allows the thermal mass in the building to cool down and therefore become a heat sink the following day.

Positioning vents for passive stack ventilationnatural stack ventilation in the Sheppard Lecture Theatre in WISE

The positioning of vents is designed to allow a through draught from one side of a room to the other and at high and low levels, to create an up-draught of warm air.

Within WISE, The tall walls of the Sheppard Lecture Theatre- standing at over 7 metres- fit very well with this design.

Mechanical ventilation

Mechanical ventilation is used in the WISE lecture theatre and in bathrooms and toilets. Low energy extraction and delivery fans help us to keep the energy usage minimal whilst meeting building regulations that require a minimum fresh air delivery to the bathrooms and toilets. Since the lecture theatre can hold up to 200 people, it has the potential to become stuffy and for carbon dioxide levels to increase, resulting in sleepy students and users. The mechanical ventilation helps to avoid this at peak loads.

A particularly important aspect of mechanical ventilation is having heat recovery, which allows incoming air to be warmed by outgoing air through a heat exchanger, therefore avoiding heat loss through the ventilation system.

Shading devices to avoid overheating in South facing roomsBuilding considerations

It is not just specific ventilation systems that help to maintain air quality in a building; in WISE, the building fabric and solar shading devices make a big difference.

Humidity is regulated by the hemp and lime external walls, which give a breathable, hygroscopic envelope. The high thermal mass materials absorb and store heat, thereby acting as a temperature buffer that reduces the need for artificial cooling.

Sliding louvered screens help to prevent overheating in the south-facing offices when they are in use in times of peak solar gain.

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