Because of several motivators, such as the mitigation of global warming, the reaching of peak oil and health concerns related to fossil fuel burning, contemporary building practise is searching for advanced concepts and technological innovations that will allow to maintain or improve the comfort level that is currently reached while reducing the energy consumption that is related to it. Ventilation is ambiguously related with this energy saving rationale. Since it makes up for about half of the energy consumption in well insulated building, it is an attractive target for energy saving measures. However, simply reducing ventilation rates has unwanted repercussions on the indoor air quality. Two main strategies have been developed to reconcile these seemingly opposing interests, namely heat recovery and demand control ventilation. This paper focuses on the energy saving potential of demand controlled mechanical exhaust ventilation in residences and on the influence such systems may have on the indoor air quality to which the occupants of the dwellings are exposed. The conclusions are based on simulations done with a multi-zone airflow model of a detached house that is statistically representative for the average Belgian dwelling. Several approaches to demand based control are tested and reported. Both energy demand and exposures are reported in comparison with a classic system, operating with continuous flowrates, that is building code compliant. This is necessary to assure that the reported energy saving potential does not derogate the indoor air quality. Within the paper exposure to carbon dioxide and to an odour tracer gas are used as indoor air quality indicators. Monte-Carlo techniques are used to ensure that the reported results are representative for the diverse boundary conditions and parameters that may occur with real life implementation of such a system. Under the conditions that were applied, reductions on the energy demand for ventilation -with the exclusion of adventitious ventilation and infiltration -of 5 to 60% can be reported, depending on the control strategy that is implemented.

Previous studies show that climate change has an impact on the damage risks in solid masonry facades. To conserve these valuable buildings, it is important to determine the projected change in damages for the original and internally insulated cases. Since historical masonry covers a wide range of properties, it is unknown how sensitive the climate change impact is to variations in different parameters, such as wall thickness, brick type, etc. A factorial study is performed to determine the climate change impact on freeze-thaw risk, mould growth and wood decay in solid masonry in Brussels, Belgium. It is found that the critical orientation equals the critical wind-driven rain orientation and does not change over time. Further, the freeze-thaw risk is generally decreasing, whereas the change in mould growth and wood decay depends on the climate scenario. Knowing the brick type and rain exposure coefficient is most important when assessing the climate change impact. For freeze-thaw risk and wood decay, it is found that simulating one wall thickness for the uninsulated and one insulated case is sufficient to represent the climate change impact. Finally, the effects of climate change generally do not compensate for the increase in damage after the application of internal insulation.

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PurposeQuality failures in the design and construction process can entail significant delays and costs. Databases of building defects have proven to be useful for drawing conclusions on underlying causes of building defects and for identifying potential improvement actions to reduce the occurrence of building defects.Design/methodology/approachThe database comprising 27,074 cases from a Belgian insurance company was studied, and it was found that moisture problems account for 48% of all building defects, and stability problems 23%. To better analyse the geographical variability, the data were enriched with demographical, geographical and climatological factors of the municipality the concerned buildings were located in. This combined information was used to determine underlying external factors that impact the probability that specific types of building defects occur.FindingsThe analysis of the data shows that external factors do indeed have a statistically significant impact. The factor with the highest impact is the number of walls the building has in common with its neighbours. The most significant climatological factor is the wind speed.Originality/valueA better understanding of the frequency of building defects and factors that contribute to the likelihood are important variables to consider in quality control and prevention.

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