Carbon dioxide (CO)-based demand controlled ventilation (DCV) is increasingly used to modulate outside air ventilation based on real-time occupancy. Its use could potentially become as common as thermostatic control is today. This article summarizes the current state of the art in CO 2 -based ventilation control including a brief discussion of the technology used, its reliability and how it is best applied. Like any control approach, the success of a C02-based DCV application is dependent on how it is engineered and installed.

Measurements of the airtightness of blocks of flats in Lithuania were carried out between 1995 and 1997 to assess the effectiveness of energy saving measures. At that time there was no real data on the airtightness of such dwellings available. The aim of the measurements was to evaluate how much heat could be saved by diminishing the air change rate. Since there are no thermostats installed in the dwellings, 'tightening' becomes the only measure available to increase indoor temperature.

The government is set to crack down on leaky buildings in 2001. So what's likely to happen and what should the construction industry be doing?