A home visit survey is carried out at a suitable time of day, followed by a report with recommendations as necessary. While on site, existing Internal Air Quality conditions are noted by using calibrated equipment for an appropriate range of measured conditions, including relative humidity and carbon dioxide. Important aspects also noted include draughtproofing, cross-ventilation, purge ventilation, background ventilation, extract ventilation and fan flow rates. The survey report sets out findings in relation to both building regulations and healthy best practice, and lists sensible changes where advisable.