PR2013

A good level of thermal insulation and an adequate thermal capacity of the building envelope are essential to achieve good energy performance. Many studies have been conducted about this topic, mostly focused on the reduction of energy losses, peak load control and energy savings. Nevertheless, very few studies were realized addressing both insulation and inertia of the building envelope in a thermal comfort perspective, and taking into account the combined effect of different ventilation strategies.

Large, multi-storey buildings pose a particular challenge for natural ventilation design due to the interaction between heat and air flows through different building zones. We develop a demand-based preliminary design strategy for sizing ventilation openings in multi-storey buildings with heated atriums. This approach enables ventilation openings on each storey, and in the atrium, to be rapidly sized so that equal temperatures and per-person flow rates can be achieved on all storeys, regardless of the occupancy or usage.

A characterization and modeling process has been conducted in order to better account for ventilative cooling in the evaluation of energy performance of buildings. The proposed approach has been tested using a monitored zero energy Active House (Maison Air et lumière) located near Paris.

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