English

Mechanical ventilation systems have been adopted in airtight energy- efficient houses in Canada to provide fresh air, remove moisture and indoor pollutants and provide a comfortable environment for the home-occupants. Homes constructed under the R-2000 Home Program are equipped with mechanical ventilation with heat recovery. Since 1984, the performance of approximately 700 R-2000 Homes has been monitored on an annual basis. This monitoring has included the measurement of indoor levels of formaldehyde and the documentation of ventilation system operation.

Infiltration heat losses due to heating appliances located within the living space are normally evaluated by reducing the conversion efficiency of the boiler, with no consideration for the fluid dynamic interaction between boiler, chimney and building. Purpose of this work is to develop a simplified mathematical model of the overall (building + boiler + chimney) system, suitable to calculate the pressure distribution and air flow rate in the building induced by the simultaneous effect of natural forces and the exhaust system.

The specific value of different flows resulting from air exchanges between rooms or with the outside is not always important. An extensive model is not suitable when only estimations or tendencies have to be drawn (very time consuming). So we developed a simplified infiltration model for predicting airflows in single rooms and between different zones of a building. We integrated this model into a building transient thermal simulation program set up to a micro-computer system. So as to obtain this model, we used simplified assumptions.

An element-assembly formulation of multi-zone contaminant dispersal analysis theory is described. In this approach a flow system is idealized as an assemblage of mass transport elements that model specific instances of contaminant mass transport in the flow system. Equations governing the mass transport phenomena modeled by each element are expressed in terms of contaminant concentration variables, the nodal concentration variables, that approximate the contaminant concentration at discrete points, the system nodes, in the flow system.

A constant concentration tracer gas (CCTG) measuring system needs a control algorithm to calculate, at each sampling time, the required tracer gas injection rate to keep the gas concentration at a target level. A new control algorithm is presented here in full detail. Practical considerations concerning modifications to take into account the physical limitations of the CCTG system and the computing of the optimal control parameters are also presented.

This work is concerned with measuring air flows between the floors of houses. A simple measuring technique is described in which two portable SF6 systems were employed. The design and construction of the portable system are presented. A comparison of air flow patterns in a superinsulated house and a standard house is made. Results showed that the air flow between the upper and lower floors of the superinsulated house was about 20 m3/h compared with 100 m3/h in the traditionally built house.

Increases in building air tightness for purposes of energy saving have, unfortunately, also led to a significant increase in the number of instances of condensation damage, particularly in domestic properties. The cost effective control of condensation is a large problem in the United Kingdom, especially for local authorities with large housing stocks.

This paper presents an analysis of indoor climate in buildings with forced air heating systems. The results is based on indoor climate measurements and extensive interviews with the occupants. The analysis shows that design criteria is of great importance for the occupants conceptions of thermal comfort in buildings with air heating systems. Forced air heating systems could be a way to provide mechanical supply air with less problems with the thermal comfort, such as draught, than in ordinary supply- and exhaust air ventilation systems.

Traditionally air has been supplied from the ceiling to the occupants below opposing the buoyancy effects due to heat convected from people, lights and machines. There has also been concern that if air supply outlets are installed at low level near people the chances of draughts and noise are high. The development of swirl air diffusers in Sweden and Germany overcomes these problems and allows a wider consideration of air distribution systems when designing buildings. This also offers flexibility in planning the distribution of electrical systems and piped services.

The paper describes measuring results of the air movement from three different types of diffusers for displacement ventilation. Two of the diffusers are lowlevel wall mounted diffusers, one with a low and one with a high initial entrainment. The third diffuser is of the floor mounted type. The air flow close to the diffusers and in the rest of the room is analysed. Velocity decay in the flow from the low-level diffusers is given as a function of the Archimeaes number, and the paper suggests a general equation for this part of the flow.