There is increasing evidence that indoor environmental conditions substantially influence health and performance. Macro-economic estimates show that the potential benefits from indoor environmental improvements for the society are high. Some calculations show that the estimated cost of poor indoor environment is higher than energy costs of heating and ventilation of the same buildings.

This paper gives an overview of a few quality assessment methods used for ventilation systems. They cover two categories of approaches: regulatory compliance checks, that are external to the building project actors; voluntary contract-based quality assessment procedures, e.g., embedded in a certification scheme. The examples are briefly described and analysed. Quantitative results are given where possible.

The European Energy Performance in Building Directive (EPBD) requires methods for the calculation of the energy performance for use in the context of building regulations.The European Commission has supplied a Mandate (M343,2004) to CEN to develop a series of standards, each covering a part of the calculation of the energy performance of buildings and procedures for the inspection of heating and airco systems.The paper introduces briefly the methods for the calculation of the energy needs for heating and cooling of buildings and the relation with the higher level standards.

Forced air distribution systems can have a significant impact on the energy consumed in residences. It is common practice in U.S. residential buildings to place such duct systems outside the conditioned space. This results in the loss of energy by leakage and conduction to the surroundings. In order to estimate the magnitudes of these losses, 24 houses in the Sacramento, California, area were tested before and after duct retrofitting. The systems in these houses included conventional air conditioning, gas furnaces, electric furnaces and heat pumps.

The ventilation of an attic is critical in estimating heating and cooling loads for buildings because the air temperature in the attic is highly sensitive to ventilation rate. In addition, attic ventilation is an important parameter for determining moisture accumulation in attic spaces that can lead to structural damage and reduced insulation effectiveness. Historically, attic venting has been a common method for controlling attic temperature and moisture, but there have been no calculation techniques available to determine attic ventilation rates.

Field tests were carried out in two flat ceiling, residential attics at a dedicated test site over a two year period. The scope of this paper is to present measurements of ventilation rates, indoor-attic exchange rates, temperatures and wood moisture contents at various locations in the attics. Attic ventilation rates are correlated with wind speed, wind direction, and attic-outdoor temperature difference. Wind speed is shown to be the dominant driving force for ventilation; however, wind direction is important particularly when the attic is sheltered.

The wind shadow model has been developed to calculate the wind sheltering effects of upwind obstacles for air infiltration calculations. This effect must be determined for infiltration calculations because, in almost all situations, only the unobstructed mean wind speed is known for a building site. This model has adapted the theoretical calculation procedures developed for far wake centreline velocity deficit calculations to near field flows, where shelter has a significant effect.

Forced air distribution systems in residential buildings are often located outside conditioned space, for example in attics, crawlspaces, garages and basements. Leaks from the ducts to these unconditioned spaces or outside can change flows through the registers and change the ventilation rates of the conditioned spaces. In this study, duct leakage flows were measured in several low-rise apartment buildings. The leakage flow measurements and other data about the apartments were used to develop a prototype apartment building.

ASHRAE has recently published its first residential ventilation standard, Standard 62.2-2003. This standard defines the roles of and minimum requirements for mechanical and natural ventilation systems and the building envelope intended to provide acceptable indoor air quality in low-rise residential buildings. The standard includes a minimum whole-house ventilation rate, local exhaust rates and other kinds of source control. This report summarizes the standard and indicates the key issues.

Infiltration has traditionally been assumed to contribute to the energy load of a building by an amount equal to the product of the infiltration flow rate and the enthalpy difference between inside and outside. Some studies have indicated that application of such a simple formula may produce an unreasonably high contribution because of heat recovery within the building envelope. The major objective of this study was to provide an improved prediction of the energy load due to infiltration by introducing a correction factor that multiplies the expression for the conventional load.