The concept of 'build tight - ventilate right' requires minimising air infiltration through theenvelope of a building and then providing adequate ventilation in a controlled manner tosatisfy the fresh air requirements of occupants. This paper describes a simple-to-use designtool (PC based and in spreadsheet format) for predicting the airtightness of office buildingenvelopes either at the design stage or before a major refurbishment.

An extensive experimental program on single sided natural ventilation was carried out within the frame of PASCOOL EC research project. Within the frame of these activities, four single sided natural ventilation experiments were carried out in a cell test, a full scale outdoor facility. Experimental data were used as input for numerical simulations that were carried out using air flow calculation tools based on network modeling as well as computational fluid dynamics (CFD). Finally, fuzzy logic techniques were used to predict the air velocity profile in the middle of the opening.

Four types of heat-pipe heat recovery systems were tested for application in passive stackventilation. The effects of fin shape, pipe arrangement and air velocity on the heat recoveryeffectiveness were investigated. The air velocity was found to have a significant effect on theeffectiveness of heat recovery; the effectiveness decreasing with increasing air velocity.The pressure loss coefficient for heat pipe units was also determined.

We examine conditions under which the natural forces of wind and buoyancy may beharnessed in order to provide ventilation for cooling. Steady-state, displacement flows drivenby combined buoyancy and wind forces are simulated at small scale in the laboratory using aPerspex box to represent a generic room or single-spaced building. Density differencesnecessary to simulate the stack effect are produced using fresh and salt water solutions. Windflow is simulated by placing the box in a flume tank; the flume produces a flow of water pastthe box and this flow is used to represent the wind.

A difficulty when designing natural ventilation in office buildings is the lack of simple designtools.In order to be able to predict natural ventilation air flow rates and indoor air temperatures atthe design stage, a computer model has been developed within the EU-JOULE projectNatvent (TM). The program is an integrated model with a thermal and an air flow modelcoupled together.

Testing was performed in 9 restaurants to identify uncontrolled air flows and pressureimbalances, building and duct system airtightness, building air barrier location, pressuredifferentials, building air flow balance, and ventilation rates. All restaurants are depressurizedunder normal operating conditions, ranging from -1.0 to -43 pascals. Space depressurizationis a function of exhaust fan flow rates, missing or undersized make-up air, intermittentoutdoor air caused by the cycling of air handlers, dirty outdoor air and make-up air filters, andbuilding airtightness.

In the framework of the Flemish Impulse Programme on Energy Technology (VLIET), the project called SENVIVV is running from January 1995 till September 1997. The major objective is to obtain a detailed picture of various characteristics of dwellings constructed during the period 1990-1995. To achieve this, a representative sample of 200 dwellings is analysed in detail. The final report of this project is expected to be available at the end of 1997.

A model for the application of probabilistic methods is the estimation of heat loss caused by convection and heat conduction through the material is developed. Temperature difference (delta T) between inside and outside of a building, air change rate (ACH) and coefficient of thermal transmittance (U-value) of the building structure are treated as random variables. The mean value and standard deviation of heat loss are estimated for different parameters of distribution for temperature difference, air change rate and thermal transmittance.

Although several investigations on how to design airtight buildings have been performedand the results furthermore have been published, many designers and contractors are stillunaware of this knowledge. Therefore, the aim of this work is to collect existing knowledgeand put it together to a practical guide. The target groups are architects, designers, contractorsand building services engineers.This paper is a summary of the report "Good Airtightness - guidelines to architects, buildingdesigners and contractors "published in Sweden during the autumn of 1997 [1].

This study aimed to research the airtightness of the building envelope in apartments before and after renovation. Measurements were carried out in three apartment buildings. One to four apartments were examined in each building. Typical renovation measures included changing the windows and refurbishing the interior surfaces. In some cases the ventilation system was renovated as well. No special emphasis was placed on the sealing of the envelope. The airtightness of the apartments increased in most cases. There were, however, apartments that became leakier during the renovation.