VC

Supermarkets are a category of non-domestic buildings with high energy use because of their operation. Recent work indicates that by improvements to the energy delivery systems through which internal environmental conditions are maintained such as thermal properties of external envelope including airtightness, HVAC systems and lighting, substantial energy savings can be achieved. Work to date has focused on typical supermarkets while the present paper examines frozen food supermarkets which include more refrigeration cabinets and therefore result in higher energy use per sales floor area.

This paper presents two case studies of stack driven ventilative cooling systems implemented in kindergarten schools located in the mild Subtropical-Mediterranean climate of Lisbon, Portugal. Both systems rely on stack driven natural ventilation supplemented by a larger, single-sided ventilation opening to be used in the warmer months. In both systems air enters the rooms at a low level, directly in front of the heating passive convector systems, and is exhausted in the back of the room, through a chimney.

Night sky radiative cooling technology using PhotoVoltaic/Thermal panels (PVT) and night time ventilation have been studied both by means of simulations and experiments to evaluate their potential and to validate the created simulation model used to describe it. An experimental setup has been constructed at the Technical University of Denmark, where the outside PVT panels are connected through a storage tank to in-room radiant ceiling panels. The radiant ceiling panels include phase change material (PCM) and embedded pipes for circulating water.

The new initiatives and regulations towards nearly zero energy buildings forces designers to exploit the cooling potential of the climate to reduce the overheating occurrence and to improve thermal comfort indoors. Climate analysis is particularly useful at early design stages to support decision making towards cost-effective passive cooling solution e.g. ventilative cooling.

Ventilative cooling (VC) is a way to cool or to prevent overheating in a building by means of ventilation rates higher than hygienic ventilation rates. To this end, natural (such as windows, vents, louvers) as well mechanical (extract or supply fans) ventilation devices can be used.

The term of “Active House” recently developed, addressing houses that target a balanced optimization of indoor environmental quality, energy performance and environmental performance. According to the idea of not only being energy efficient and eco-friendly, Active Houses equally focus on indoor environmental qualities, in particular daylight and air. With their tendency towards intensive sun penetration, natural ventilative systems and generally intensive connections to the exterior, Active Houses challenge the balance of technical and individual indoor climate control.

In both, newly built and renovated buildings the building air-tightness has to be ensured. With a tight building envelope comes a low infiltration air-exchange. A minimum outdoor air exchange to ensure acceptable moisture and indoor air quality levels must be maintained. A model is introduced, that couples hygrothermal whole building simulation with a multi-zone air-flow simulation.

Zero Energy Buildings require airtightness and mechanical ventilation systems to provide air changes and energy saving. These requirements contrast with the principles of natural ventilation. Through a case study located in Modena, Italy, a design strategy is proposed as a solution to integrate natural and mechanical ventilation systems at different times of the year to reduce the energy consumption in a newly designed high-density ZEB. The internal comfort evaluation for the warm season is then verified with a multizone dynamic simulation and a CFD analysis.

Higher insulation and air tightness levels of buildings, increase the risk on overheating. Ventilative cooling as passive technique can limit overheating and decrease cooling energy consumption. The national energy performance regulations (EPBD) determine whether, how and under which requirements ventilative cooling can assist to reduce cooling demand and overheating. Therefore, those regulations are a key factor in the market uptake of ventilative cooling. Without a realistic and achievable approach, ventilative cooling will marginally be applied in buildings.

Passive cooling by night ventilation is one of the most promising approaches to reduce cooling energy demand of office buildings in moderate climates. However, the effectiveness of this system depends on many parameters.