The French regulation on residential building ventilation relies on an overall and continuous airrenewal. The fresh air should enter the building through the habitable rooms while the polluted air isextracted in the service rooms. In this way, internal air is drained from the lowest polluted rooms to thehighest polluted ones. However, internal pressure equilibrium and air movements in buildings resultfrom the combined effects ventilation system and parameters such as wind, temperature difference or doors opening.

Passive cooling of buildings is one of the energy-saving measures that can be employed in climateswith predominantly sensible cooling loads. There are several passive cooling techniques that can be used in buildings; among them night-time ventilation. Night-time ventilation cooling utilizes diurnalswing of outdoor temperature and it has been used in many buildings. However, this passive coolingtechnique only works well when a building has a sufficient thermal mass.

In most Dutch classrooms draught results in insufficient ventilation and poor air quality during the heating season, adversely affecting the well being and performance of pupils. Also a considerable part of the year the risk of overheating is high due to the high internal heat load. New analyses show that over 85% of time the heat load and not minimum indoor air quality is the determining factor for the required amount of ventilation. That is if passive cooling is to be preferred above mechanical cooling, with regard to energy conservation.

Due to increasing interest in indoor air quality and demand controlled ventilation in buildings aiming at energy and cost saving, as well as health and comfort aspects, the objective of our work has been the development of a reliable, low cost tool for demand ventilation control. Based on a single microelectromechanical (MEMS) metal oxide semiconductor (MOS) gas sensor VOC detection as close as possible to perceived air quality and additionally, a good correlation with measured CO2 concentrations due to implementation of an empirical data evaluation algorithm has been achieved.

The dependence of the ventilation on the indoor particulate pollution is highlighted by numerousstudies. The aim of the present study is to examine the influence of the ventilation on the levels of theparticulate concentrations found in dining halls where a large number of students are accommodated. Indoor particulate sources were also quantified.Measurements were conducted in four University dining halls, which are located in different parts ofthe city of Athens.

Since the 2002/91/CE EPBD was published, all European countries should making efforts in harmonizing local standards, imposing the assessment of building energy and environmental impact through a common certification procedure. Generally speaking, as a matter of fact, beside the main problem of different methods and tools adopted for evaluating the building energy balance, ventilation is still one of the controversial issues, since each country refers to different local requirements regarding the air-change rate values to be used when performing the calculation.

International building legislation is setting stronger and stronger requirements for the energy performance of buildings. An actual example is the impact of the Energy Performance of Buildings Directive in the European Union (EPBD) on the national requirements in the Member States. The improved energy performance of buildings cant be achieved by additional insulation or more effective buildings systems only. A major influence factor on the energy quality is the ventilation technology and also the airtightness of the building envelope.

Thermal bridges increase the building energy demand for heating and cooling. For well insulatedenvelopes and buildings with increased energy efficiency, the influence of thermal bridging on theenergy consumption is of major importance. Here the ratio between the thermal bridging effect and the overall thermal losses increases compared to low or medium insulated buildings and it is possible that the effect of thermal bridges on the energy demand compensates or even overtakes, for instance, the energy gain provided by thermal solar collectors for domestic hot water.

For quite a long time energy conservation and energy efficiency were concentrated on a singlebuilding approach. Until 2000 nearly all national building regulations were based on net energybalances (energy needs) comprising transmission losses, ventilation losses, solar gains, internal gains and heating gains. Due to that the development focused on reduced transmission and ventilation losses, and so-called low energy houses or passive houses were designed and demonstrated in pilot projects, at first for new constructions and later on also for refurbishment projects.

The office building belonging to the Remscheider Entsorgungsbetriebe REB (Waste DisposalUnit in Remscheid), which was constructed in 1968, was thoroughly renovated in 2004. Theutilisation quality was greatly improved with a combination of measures including efficientthermal insulation and solar control, fan-controlled ventilation, better use of daylight andactive use of solar energy for domestic hot water - while the energy consumption valueswere reduced appreciably at the same time.A key aspect of the renovation was to improve comfort during summer without applyingactive air-conditioning.