Good indoor air quality in buildings becomes such a major concern that new design recommendations emerge in many countries (USA, Nordic Countries,...). Improvement of the interior environment should not beat the expense of higher energy consumption. Heat recovery systems are one appropriate answer to this challenge. However, additional energy savings could be achieved by applying demand controlled ventilation when the internal loads vary significantly. A CO2 controlled ventilation system has been installed in a conference room with high variable occupancy in mid 91.
Describes the activities of Annex 18, whose objectives have been to develop means, methods and strategies for DCV systems and to contribute to the implementation. A DCV system in this annex is defined as a ventilation system in which the air flow rate is governed by airborne pollutants.
A literature search was performed to gain as much knowledge as was available on ventilation, indoor air quality sensors and demand controlled ventilation (DCV) strategies. Field data was gathered on the time and spatial variation of indoor air quality in houses. Appropriate designs were then developed. Design strategies are discussed elsewhere (1). Hour by hour simulations of the performance of several ventilation systems in various Canadian climates were done. Energy savings were then estimated for DCV and heat recovery ventilation with air to air heatexchange.
Demand controlled HVAC-systems have many advantages. The principle is to optimize comfort and to minimize energy consumption simultaneously. In modern office buildings, indoor temperature is very often a useful control parameter. Thequestion is, whether it should govern the system for each room individually or for a zone. In the latter case: how shall the zones be defined? Above all, performance criteria have to be weighed against the investment cost. This paper discusses different strategies, which have been or are going to be realized for office buildings.
This paper evaluates the suitability of humidity-controlled house ventilation system to determine (i) the effectiveness of relative humidity as a sensing element, and (ii) the operating and performance characteristics of such ventilation strategy. The ventilation system consists of continuously running "mechanical" air extractor units and "passive" air inlet units equipped with humidity sensors. The ventilation system was installed in two single storey houses which were monitored during November 1989 to April 1990.
A conference room has been converted to temperature- and carbon dioxide controlled ventilation. A number of tests have been conducted with the system in different load conditions. The variables that have been measured are air flow rate, temperature and carbon dioxide concentration. The activity in the room during the measurements has also been well recorded. The main purpose has been to evaluate the ability of a demand controlled ventilation system to maintain a good indoor air quality.
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