The passive cooling techniques such as night time cross ventilation is potentially an interesting strategy to provide substantial cooling energy savings in warm climates. The efficiency of the night cooling ventilation is determined by three main factors: the external air flow rate in the room, the flow pattern and the thermal mass distribution. Most of the software used to simulate building thermal performance assumes natural convection in the enclosure; therefore the convective heat transfer coefficients for internal room surfaces are underestimated.

Natural ventilation driven by the combined forces of wind and buoyancy has been studiedexperimentally for a building flanked by others forming urban canyons. The steady ventilationestablished in an isolated building was observed to change dramatically, both in terms of the thermalstratification and airflow rate, when placed in the confines of an urban canyon environment. Theresulting ventilation flows and internal stratifications are presented for different combinations of windspeed, opening area and location, and canyon width (building density).

Cross ventilation is one of the most important techniques for maintaining a comfortable indoorenvironment in hot and mild seasons with less cooling energy. But, at present, it is difficult to designindoor environment under cross ventilation because there is insufficient knowledge to evaluate theeffect of cross ventilation quantitatively. Thus the full-scale model experiment has been done in a large wind tunnel to examine the airflow property in the cross-ventilated space.

Ventilation is essential for health and comfort of building occupants. It is particularly required to diluteand/or remove pollutants emitted by occupants metabolism. The concentration of metabolic CO2 iswell correlated to metabolic odor intensity. Therefore CO2 concentration can be efficiently chosen asan indoor air quality indicator when occupants are the main pollution source inside the buildings.

Dynamic analysis is very useful to obtain thermal properties of building components. However different methodologies can be applied, and several software tools based on these methodologies are available which application requires certain degree of experience. The main differences between methodologies are the numerical procedure and the model assumed to estimate the required parameters. Different approaches can lead to different and even wrong estimations of the parameters.

The use of electricity in buildings constitutes around 16% of Singapore’s energy demand. To incorporate energy efficiency measures is one of the key mission to ensure that the economy is sustainable. The recently launched building energy efficiency labell

The process of implementation of the EPBD in Austria is now carried out for several years. Thecalculation scheme for asset rating is finished, the operational rating procedure is still being discussed.One of the major problems in Austria is the fact that most building laws are under the responsibility ofthe nine Austrian provinces. Therefore all political decisions like baseline and limits of the energydemand for the building codes are difficult to achieve. These values are therefore still underdiscussion.

Available time for building construction is getting shorter, therefore the number of buildings which are built with lightweight building elements (LBE) is increasing. LBEs are elements of greater dimensions with low specific weight and low thermal transmittance. Their characteristic is also low thermal stability. By upgrading LBE with dual ventilated cavities (DVC) with counter flow becomes standard LBE a thermally activated building construction with increased thermal resistance and thermal stability. It enables using of solar radiation and heat recuperation from used air.

The EPBD prescribes an energy performance certificate for buildings. According to the nationalimplementations of the EPBD for non-domestic buildings the specific data of the building will begathered during the certification process and combined into a multi zone model describing buildingand building systems from an energetic point of view.

The potential for passive cooling of roof slabs incorporating an air cavity is important with respect tothermal comfort. Roof systems in traditional buildings, incorporated a ventilated roof or an air cavity.The concept has been proposed again in contemporary buildings in the construction of roof slabs,using a modular formwork system, where the cast in situ concrete slab is isolated from the screed with the introduction of a ventilated air space. The cavity is primarily intended to curtail the conduction and inward radiation of heat from the intense solar insolation on the concrete roof.