In low energy dwellings the ventilation heat losses are significant. Reduction of these heat losses can be achieved by introducing demand controlled ventilation i.e. ventilation rates are set below normal level when rooms are no longer occupied. This paper outlines preliminary results on energy conservation and health effects in relation to demand controlled ventilation in a low-energy house.

This paper shows that it is possible to calculate the optimal outdoor air rate at different outdoor temperatures in the economiser cycle. The price of heat must increase 3 times before the optimal outdoor air rate during heating gets lower than during cooling. The optimal outdoor air rate during heating is determined primarily by the price of heat. The optimal outdoor air rate during cooling is determined primarily by the price of cooling capacity.

This paper shows that well proved state-of-the-art technology can be utilized to keep annual average energy consumption in office buildings below 130 kWh/m2, which is well below today's average, without compromising any major functional or architectural concepts of modern design. The Norwegian building regulations, which were revised in 1997, demand calculation of energy consumption for new buildings. However, the minimum requirements to energy consumption can even be satisfied with a modest degree of insulation or high internal loads.

Even in cold climates, offices normally need to be cooled due to the internal heat loads from people, equipment and lighting. Either a chilled ceiling or chilled beams with cooled water as medium or chilled air can be used. In the case with chilled ceiling or chilled beams, a constant air volume system (CAV) is used. In the case of air only, a variable air volume (VAV) system must be used. This paper presents the advantages of the two methods of cooling with respect to energy use, which was calculated from climate data.

Even though simulation is being increasingly used in design of modern buildings, the full potential of simulation is usually not achieved. To improve building and HVAC system performance, designers usually guess different values of design parameters and then redo the simulation without actual knowing if the guessed value will lead to improvement. This is inefficient and labor intensive. In addition, if the number of design parameters being varied exceeds two or three, the designer can be overwhelmed in trying to understand the nonlinear interactions of the parameters.

A question raised about displacement ventilation, is whether floor heating can be utilised without disturbing the thermal stratification in the room. See Figure 1.Q?Figure 1 Too much floor heating may destroy displacement ventilationThis paper deals with the possibilities and limitations to floor heating with displacement ventilation. This paper shows that floor heating can be utilised with displacement ventilation for both industrial and non-industrial premises for normal airflow rates and normal floor heating rates.

The paper describes a system solution developed in Sweden for domestic buildings with pre-cast concrete units where the floor consists of a 0,06 meter thick concrete slab with a framework casted into the slab and a beam. The beams acts as floor beams forming a cavity of about 0,3 meter that are used for plumbing, electric installations and transport of air for heating and ventilation. The air is blown from the cavity into the rooms through narrow slots along the walls. Air for heating is recirculated through a ventilation plant consisting of filter, heating element and a fan.

To obtain stable control of VAV systems, many considerations must be accommodated properly. Local and central control loops affect each other in ways that in many cases can lead to problems of poor control and even instability. In a VAV system (utilizing demand controlled ventilation), the stability of the supply air temperature must be very carefully commissioned. While stable control can be obtained more easily at full flow rates, instability can often become a problem during reduced flow rates.

In this study the performance of a double-skin façade in an office building equipped with a hybrid ventilation system was analyzed. The hybrid ventilation system studied was based on a low-pressure mechanical exhaust system and demand control of ventilati

For energy savings, DCV systems are more and more used on ventilation systems. In France, in non residential buildings, these systems are generally controlled by either a CO2 sensor, or an optical movement detection (infrared). To achieve correct performances, pressure conditions in duct and fan regulation must be considered.