This work is based on the RESHYVENT project  in which the effectiveness of hybrid (i.e. combined natural and mechanical ventilation) was measured and investigated in the urban canyon of Athens, Greece – the most important conclusion being that natural ventilation is dominant. It is suggested that the individual reaction to Air Conditioned Buildings should be better investigated, since many people ask for the comfort associated with natural ventilation. 

Common experiences, standards, and laboratory studies show that increased air velocity helps to offset warm sensation due to high environmental temperatures. In warm climate regions the opening of windows and the use of desk or ceiling fans are the most common systems to generate increased airflows to compensate for higher environmental temperatures at the expense of no or relatively low energy consumption.

Public residential buildings in Singapore are designed as naturally ventilated. As climate changes, the indoor thermal comfort becomes critical as it depends greatly on the outdoor weather condition. The Predicted Mean Vote (PMV) model developed for Singapore (Givoni, et al., 2006) which depends on indoor air temperature and air speed is used to predict the indoor thermal comfort.

The climate of Greece is typical Mediterranean with wet, cool winters and hot, dry summers. The temperature range is on average between 5°C to 35°C without many extreme temperatures and weather events. The cool sea breeze on the islands makes summer conditions milder. According to researchers and assessment reports of the United Nations climate change is inevitable in the 21st century. Regional climate models related to Greece show low uncertainties.

Night ventilation has been applied successfully to many passively-cooled or low-energy office buildings. This paper analyses the thermal comfort achievable according to European standard EN 15251:2007 by applying this strategy in office buildings in Spain. Specifically, the comfort level is evaluated using the Degree Hours (DH) criteria and the maximum indoor temperature.

Passive cooling in the built environment is now reaching is phase of maturity.  Passive cooling is achieved by the use of techniques for solar and heat control, heat amortization and heat dissipation. Modulation of heat gain deals with the thermal storage capacity of the building structure, while heat dissipation techniques deal with the potential for disposal of excess heat of the building to an environmental sink of lower temperature, like the ground, water, and ambient air or sky.

Developing a method to optimize the investment cost of a building and the energy performance, represented by the energy consumption, one gets easily confronted with conflicting objects.  As the investment cost usually rises, while the energy consumption shrinks it is somehow difficult to find an optimal solution.  The utopic point would be the point where saving energy doesn’t cost athing, or even better: earns the occupant extra money.  Reality however shows different: restricting the energy losses almost always implies an investment.  The simplest example is increasing the thermal resista

Ventilation is especially important to get a good Indoor Air Quality in schools. This is important as the young children have very vulnerable still developing longs which are very sensitive to all kind of pollutions. During the last decade different types of sustainable schools were built. The first schools were like very well insulated schools up to the Passive House standard. The next step in this development are schools which generate more energy hat they need themselves: Plus Energy schools. In 2011 a first school of this type was built in the Netherlands.

ID is a design procedure that considers the building as a whole system with the aim of optimizing it throughout the lifecycle. ID can be used to reach high ambitions by developing, discussing and evaluating a scheme using a multidisciplinary team from the initial design phases and it is a proven approach for achieving high-performance buildings with good indoor environment without sacrificing architectural quality or result in excessive costs. Integrated Design support designers in delivering buildings which satisfy occupant’s needs much more than conventionally designed buildings.

The airtightness of the building envelope was studied in field measurements in recently constructed experimental small test buildings. Two types of research studies were carried out: the effect of special air tight sealing and the experimental determination of air exchange rate (h-1) under real operating conditions. In very small buildings with many joints between materials and construction the role of the air tight sealing is very important; the experiments show changes in measured air tightness.