Building performance can be expressed by different indicators as primary energy use, environmental load and/or the indoor environmental quality and a building performance simulation can provide the decision maker with a quantitative measure of the extent to which an integrated design solution satisfies the design requirements and objectives. In the design of sustainable Buildings it is beneficial to identify the most important design parameters in order to develop more efficiently alternative design solutions or reach optimized design solutions. A sensitivity analysis makes it possible to identify the most important parameters in relation to building performance and to focus design and optimization of sustainable buildings on these fewer, but most important parameters. The sensitivity analyses will typically be performed at a reasonably early stage of the building design process, where it is still possible to influence the important parameters. The methodology is presented and an application example is given for design of an office building in Denmark.

Personal exposure in a displacement ventilated room is examined. The stratified flow and the considerable concentration gradients necessitate an improvement of the widely used fully mixing compartmental approach. The exposure of a seated and a standing person in proportion to the stratification height is examined by means of full‐scale measurements. A breathing thermal manikin is used to simulate a person. It is found that the flow in the boundary layer around a person is able to a great extent to entrain and transport air from below the breathing zone. In the case of non‐passive, heated contaminant sources, this entrainment improves the indoor air quality. Measurements of exposure due to a passive contaminant source show a significant dependence on the flow field as well as on the contaminant source location. Poor system performance is found in the case of a passive contaminant released in the lower part of the room close to the occupant. A personal exposure model for displacement ventilated rooms is proposed. The model takes the influence of gradients and the human thermal boundary layer into account. Two new quantities describing the interaction between a person and the ventilation are defined.

In real-life ventilated enclosures like operating rooms movements take place. Persons' movements may influence the local flow field as well as the contaminant field substantially. Most often movements are ignored in simulations due to the complexity of the phenomenon. This paper presents an indirect and simple method to consider the influence of movements that may enable modelers to include this important phenomenon in the engineering application of CFD. This may improve practical risk assessment--for instance risk assessment of unintended transport of bacteria during orthopedic surgical operations that may jeopardize the hygiene.

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An intervention study was performed in a mechanically ventilated office building in which there were severe indoor climate complaints among the occupants. In one part of the building a new heating and ventilation strategy was implemented by renovating the HVAC system, and a carpet was replaced with a low-emitting vinyl floor material; the other part of the building was kept unchanged, serving as a control. A comprehensive indoor climate investigation was performed before and after the intervention. Over a 2-week period, the occupants completed a daily questionnaire regarding their comfort and health. Physiological examinations of eyes, nose and lungs were performed on each occupant. Physical, chemical and sensory measurements were performed before and after the intervention. The renewal of the flooring material was performed after a sensory test of alternative solutions in the laboratory. Before the floor material was installed in the office building, a full-scale exposure experiment was performed in the laboratory. The new ventilation strategy and renovation of the HVAC system were selected on the basis of laboratory experiments on a full-scale mock-up of a cellular office. The severity of occupants' environmental perceptions and symptoms was significantly reduced by the intervention.

Traditional building energy consumption calculation methods are characterised by rough approaches providing approximate figures with high and unknown levels of uncertainty. Lack of reliable energy resources and increasing concerns about climate change call for improved predictive tools.A new approach for the prediction of building energy consumption is presented. The approach quantifies the uncertainty of building energy consumption by means of stochastic differential equations. The approach is applied to a general heat balance for an arbitrary number of loads and zones in a building to determine the dynamic thermal response under random conditions. Two test cases are presented.The approach is found to work well, although computation time may be rather high. The results indicate that the impact of a stochastic description compared with a deterministic description may be modest for the dynamic thermal behaviour of buildings. However, for air flow and energy consumption it is found to be much more significant due to less "damping".Probabilistic methods establish a new approach to the prediction of building energy consumption, enabling designers to include stochastic parameters like inhabitant behaviour, operation, and maintenance to predict the performance of the systems and the level of certainty for fulfilling design requirements under random conditions.

To facilitate the decision‐making and communication, an evaluation method has been devised that incorporates environmental effects of the energy use with thermal and atmospheric indoor climate in a score on an absolute scale from 0–100 %, called the “Eco‐factor”. This factor is based on indicators of physical properties. For the indoor climate part these include mainly the indoor temperature, velocity, and concentration fields. The energy part considers the energy distributed to energy sources, and the environmental effects of the resulting airborne emissions evaluated by Life Cycle Assessment (given by default figures from a database). The tool is used to make an overall assessment of the quality of design alternatives, where the “costs” (energy) is compared to the “benefit” (indoor climate), and to identify possibilities for improvement. The paper shows a model case study of an office building, where choices are considered that must be made in an early design phase.

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