English

The present paper addresses experiences with infiltration and ventilation in the Active House concept, based on the Active House Specification and realized Active Houses. The Active House Specification is based on a holistic view on buildings including Comfort, Energy and Environment. It uses functional requirements to indoor air quality and thermal comfort, and does not have component requirements to airtightness or specific ventilation solutions. Experiences from realised Active House projects show that better airtightness than nationally required has been achieved.

This paper describes the method, in which human observers assess indoor air quality. This method is at present necessary to determine actual levels of air quality indoors in non-industrial buildings to fulfil comfort requirements specified by the standards. The paper attempts to identify the potential drawbacks of the method, its limitations and the factors influencing these measurements. Examples are given illustrating, how the measurement uncertainty influences the estimated level of indoor air quality.

In building design, energy performances are commonly predicted based on deterministic stationary or dynamic calculations. However, many contributing parameters are inherently uncertain, resulting in potentially unreliable values for the performance indicators. To overcome this, a probabilistic design method is recommended to take uncertainties into account. Such uncertainty-based optimisation often requires many simulations, making it extremely time-consuming. To avoid this, meta-modelling can be of interest. A meta-model mimics the original numerical model with a simplified fast model.