A test room with a Displacement Ventilation System was built. Temperature control was provided with a DDC (Direct Digital Control) System, controlling the air volume and the air inlet temperature. Air velocity and temperature profiles were measured at different locations in the room for various internal loads. The aim of the control was not only to provide a constant temperature but also comfortable conditions. the temperature gradient, the air velocity and the radiant heat exchange were taken into consideration for the comfort condition in the space.

Modern one-family houses in Scandinavia are often ventilated by an exhaust fan. Most of the outdoor air probably enters through whatever cracks and openings there are and only a small part enters through the supply vents in many of these houses. The overall supply of outdoor air might be adequate, but some rooms often do not get enough of outdoor air. The constant concentration tracer gas technique was used to examine the supply of outdoor air. Fan pressurization combined with infrared photography were employed to characterize the air leakage of the building.

In Halmstad a multi-apartment house has been built with air carried heating. Fresh air was used as the only heat carrier. To improve the air quality it was decided not to use circulation flow, which is normally required for air carried heating. Theheating requirement was obtained with a higher air flow than what the standard requires. This also implied improved air quality. The standard specification states 0.5 changes per hour as the minimum requirement, but in Halmstad the house was ventilated with 0.7 - 1.0 changes per hour.

The performance of a system for demand-controlled ventilation was investigated for a period of 1.5 years. Presence sensors of the passive infrared type are used to control the ventilation rate in each classroom. The signal from the presence sensors was recorded, as well as the CO2 concentration in the classrooms. One of the classrooms was equipped with displacement ventilation. A comparison was made between displacement and mixing ventilation to investigate the CO2 concentration in the stay zone.

Field investigations were undertaken on five houses to determine the potential for improved performance and lower costs through the use of a demand controlled ventilation (DCV) systems. All 5 houses were energy efficient, low toxicity construction, and were chosen to reflect a range of mechanical systems consistent with Canada's new ventilation standard (CSA F326). Three of the test houses were extensively monitored and, after 90 days of conventional operation, were converted to DCV using a wide variety of sensors and controls.

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.

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.

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.

A test programme has been designed to evaluate the performance characteristics of sensors for the automatic control of ventilation rates. The test programme consists of two main parts, one being the evaluation of sensor performance in laboratory tests and the other referring to long term characteristics of sensors in actual buildings. Included in thepresent evaluation are eight different types of humidity sensors, two carbon dioxide sensors and five mixed gas sensors.

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.