Mark Phillips and Richard Woolley, proud manufacturer representatives of London-based Airflow, shows off Duplexvent DVS 2200, a mechanical ventilation heat recovery (MVHR) unit at Ecobuild 2011. (Photo by Mignon O’Young)

Mark Phillips and Richard Woolley, proud manufacturer representatives of London-based Airflow, shows off Duplexvent DVS 2200, a mechanical ventilation heat recovery (MVHR) unit at Ecobuild 2011. (Photo by Mignon O’Young)

Mark Phillips and Richard Woolley, proud manufacturer representatives of London-based Airflow, shows off Duplexvent DVS 2200, a mechanical ventilation heat recovery (MVHR) unit at Ecobuild 2011. (Photo by Mignon O’Young)