By Peter Childs
Head of School, Dyson School of Design Engineering, Imperial College London.
I have been involved in a sustained study of an innovative ventilation system for buildings. The company, Ventive, is now in revenue and growing and a link to its latest investment round can be found below, along with a resumé of the technology:
Historically, housing has had low levels of insulation and poor airtightness. Although this characteristic was not energy efficient it provided a plentiful supply of fresh air. Over the last twenty years insulation and airtightness of homes has received attention due to a global drive towards energy efficiency and carbon emissions reduction. Since a large portion of energy used in homes is utilised for comfort heating or cooling, the focus has been on improvements to insulation and airtightness in order to decrease the dwellings’ total energy use, as well as ensuing carbon emissions. However, a large body of research shows that airtight houses require adequate air management (controlled ventilation) to prevent the occurrence of poor indoor air quality which can contribute to illness such as asthma as well as the so-called sick building syndrome.
Introduction of controlled ventilation presents another energy related challenge – fresh air introduced to homes needs to be re-heated (or cooled) adding to energy use and negating most gains resulting from improved insulation. An air management system that can improve building ventilation, prevent excessive heat loss and use no energy in operation is a desirable option. The Ventive PVHR technology can be such an option that provides efficient ventilation with heat recovery and no electricity use. This system utilises both thermal buoyancy and pressure caused by the wind-driven Pitot effect of a cowl as its two driving forces. Advances in heat exchanger design resulting in interleaved coaxial heat exchanger units allow the thermal energy of the outlet air to be exchanged to the cooler inlet air with consistently high efficiency and negligible pressure drop. Thus heat loss due to air ventilation can be minimised and the running costs avoided. The PVHR system, fitted into an airtight and insulated test room, has been tested replicating different housing types and under different environmental scenarios. An academic paper reporting some of the work is available at: