WHoLE-PVS
Whole House Low Energy Passive Ventilation System
 

The Problem

There are widespread concerns about air quality in new houses. Dwellings are being more tightly sealed to avoid heat loss and concentrations of indoor pollutants are growing (VOCs, particulates, cigarette smoke and condensation). Higher volumes of winter background ventilation are required to disperse these pollutants because of the health risk. However, as the standard of insulation in buildings improves, ventilation heat loss becomes an increasing proportion of a building's energy consumption.

A solution

The supply air window is typically a double glazed window with an extra external pane forming an air path. The principle of operation of the window is to draw ventilation air from the outside via a vent at the bottom of the outer glazing, through the air path to enter the room through a vent at the top of the inner window. Solar gains pre-heat the ventilation air during the day, and at night a proportion of the heat lost through the inner glazing is recovered in the ventilation air. Low effective U-values can be achieved with this concept, by optimising the existing window technology, e.g. the use of low emissivity coatings. The window also uses innovative pressure-controlled vents, which improve heat reclaim efficiency and a more stable ventilation rate using a PSV.

The Project

This project intends to improve guidance for innovative use of materials and components in housing, by demonstrating a successful 'Whole House Low Energy' passive ventilation system involving the use of 'supply air' windows in conjunction with passive stack vents (PSV), to reduce overall energy consumption and improve indoor air quality. The system is made from components that already exist, or that can be readily manufactured, and is easily installed, both in new-build and retrofit applications. Therefore, there are are no practical barriers to its implementation.

Some Background

A number of solutions which aim to resolve the conflict between the requirements for health and energy conservation in housing have been the subject of recent research, for example
  • Positive Input Ventilation
  • Dynamic insulation
  • Mechanical Ventilation and Heat Recovery (MVHR).
These systems aim to improve both the energy efficiency and the indoor air quality, compared to the use of conventional trickle vents and extract fans. However, capital, maintenance and running costs may be high, and buildability may be an issue for dynamic insulation. By comparison, the Whole House Low Energy Passive Ventilation System (WHOLE-PVS) is easy to install in new houses and, importantly, when retro-fitting existing buildings.

This proposal is for the first comparative study of the alternative technologies. The WHOLE-PVS incorporates supply air windows in each room of a house, together with passive stack vents in the kitchen and bathroom. The WHOLE-PVS is now being installed in flats and houses in Denmark, Ireland and Poland following an award of substantial funding from the EU Energie programme to develop the system. This application is in respect of the additional cost of demonstrating this proven technology in the UK and disseminating the results through a website and a variety of guidance documents. The demonstration will take the form of a live case study, and will form a focus for the dissemination of the results and be the system's first application in mainland Britain. A comparison will be made with previous applications of other innovative solutions, as well as established technologies such as trickle vents and MVHR.

The concept of the supply air window was first tried in Canada and Finland in the 1970s and 1980s. The project team has improved the design of the window, particularly by the use of pressure-controlled vents to improve its heat reclaim efficiency. Both testing and computer modelling have been used in its optimisation.

The Team

The partners in this project bring a balanced and integrated composition of:
  • A national building research agency,
  • two manufacturing companies (SMEs) with active research and development programmes;
  • a consultancy with considerable expertise in building performance;
  • a leading housing association;
  • a university research department with a long established reputation in building simulation and analysis and
  • a key housing sector organisation providing a strategic overview.

Website by Cambridge Architectural Research Ltd.
Site Hosted by University of Cambridge Department of Architecture
Updated: 3 October 2002.

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