Passive Stack Ventilation for lifetime housing

(17/01/2008)

Cymdeithas Tai Clwyd aims to create ‘lifetime’ housing and is now developing two sites fulfilling the principle, on a site in Chirk owned by the Council and already being developed for community facilities including a new surgery, and at Llansilin.

The seven three person, two bedroom bungalows at Chirk and four houses and two bungalows in Llansilin are being specifically built to a pattern evolved by Cymdeithas Tai Clwyd and its architect Ainsley Common Associates, aimed at ensuring the homes are not only flexible to accommodate tenants’ changing needs but also to be as economic to occupy as possible. As a result, timber frame construction techniques giving properties with a U value below 0.2W/m2K and Passivent natural ventilation are incorporated as standard.

Each of the homes features a Passivent ‘whole house’ Passive Stack Ventilation (PSV) system. Passivent ‘whole house’ ventilation systems introduce the concept of planned air paths into the home to ensure that all the rooms in a property are effectively ventilated. Moisture laden air is extracted from ‘wet’ rooms of bathrooms and kitchens, with air inlets in ‘dry’ rooms only (living rooms and bedrooms) providing a supply of fresh replacement air. The strategic siting of the inlets ensures that air always moves from ‘dry’ rooms to ‘wet’rooms, from where it is extracted in conjunction with the moisture.

Passivent Passive Stack Ventilation (PSV) is driven primarily by the natural stack effect whereby warm air rises, to extract moisture laden air directly from the ‘wet’ rooms. Humidity sensitive ceiling or wall mounted extracts are linked via ducting to terminals on the roof. The extracts open and close automatically in response to changes in relative humidity allowing moist air to rise up the stack, enhanced by wind blowing across the roof (the venturi effect), thereby exhausting the moist air directly to the outside.

Passivent PSV helps maintain a dry, draught- free, fresh environment within and provides effective condensation control. The system has no mechanical parts to go wrong or need replacing, operates silently, does not need any electricity, and is not dependant on human input switching it on or off for operation.

Bryn Davies, Development Manager at Cymdeithas Tai Clwyd, commented: “These are exciting developments for us and our tenants. We aspire to giving our tenants a sense of wellbeing, but are also conscious of issues such as fuel poverty so aim to build homes that are as economic as possible to run. The Passivent ventilation is important in helping realize both objectives. It ensures the homes remain dry, fresh and condensation free, without draughts. As it does not require electricity to operate, it costs the tenants nothing to run, and the tenants do not have to worry about physically switching the ventilation on or off.”

Passivent offers independent BBA certification across its range, proven in use for over 20 years. In addition to its natural (PSV) and assisted ventilation (MEV) systems, it supplies a comprehensive range of background trickle ventilators, the Fresh range of through wall ventilators, with or without acoustic options, all of which contribute towards efficient ventilation of the home with little or no energy consumption. Passivent is part of the Building Product Design Group.

Related categories:  Air movement and Fans   Residential applications   Ventilation