English

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.

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.

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.

Every city or town has a market to supply fresh food to its residents. A market has the function of displaying fresh food, auctioning it, and supplying it to consumers. A market must fulfill this role throughout the year even in cold, snowy areas, and this calls for a large, covered space. At the same time, vehicles of various sizes drive in and out of the market premises to transport food into and out of the market. These vehicles emit exhaust gas, however, and the introduction of a large amount of fresh air into the market space is indispensable for maintaining good air quality.

We designed a roofed parking lot for a large wholesale market in Sapporo City to protect trucks and cars from snow and rain. Every day, the area attracts a large number of vehicles including trucks. Drivers often leave the engines running for heating in winter and cooling in summer. Exhaust gases poison the air, creating a serious environmental problem. The roof of the new parking lot is equipped with two kinds of chimneys, such as high chimneys to exhaust waste air and low chimneys to supply fresh air.

This paper is concerned with the different methods to present inlet condition for computational fluid dynamics (CFD) simulation of task air conditioning (TAC). The boundary conditions at the supply opening have a strong influence on the flow in the room, and they are, therefore, very important. Usual methods are outlined. Comparison and analysis are then given. The terminal device of TAC is close to people and is relatively large compared to the dimension of the occupied zone. The occupied zone is in the forward flow zone, not return flow zone.

The airflows of rooms are different with the ventilation methods, indoor heat sources distribution, as well as room structures themselves. To understand the features of indoor airflows, engineers and researchers use laboratory tests, CFD techniques and field investigations to probe into the essences of indoor air movements. At present, CFD methods are widely used in predicting space air distributions because of lots of well-known advantages. On the basis of long-term research work, the 3DFLOW codes were developed, which is based on the standard three-dimensional ?

Theoretically if the thermal properties of a building envelope and the power of the HVAC systems are known, then air infiltration becomes the only one unknown component of the thermal balance of a building and could be defined from it. In reality, all data are approximate. Modern measurements and data processing techniques allow one to evade this obstacle.