New and refurbished buildings have to relate to ever increasing standards regarding energy efficiency and energy consumption. This results in well insulated building envelopes with low air leakages offering reduced heating demands. One of the downsides of this is that these buildings are easily warmed up to such a degree that in order to sustain an acceptable indoor climate, removal of excess heat becomes a necessity. The removal of surplus heat is often done through means of mechanical cooling. However, energy consumption related to mechanical cooling is considered incompatible with achieving zero energy buildings (ZEB). As a response, the use of Ventilative cooling (VC) solutions is settling, and it is by many considered crucial in realizing ZEB. Ventilative cooling refers to the use of ventilation air in order to reduce or eliminate the need for mechanical cooling. VC can be applied through both mechanical and natural ventilation strategies, as well as a combination. To achieve efficient VC while ensuring an acceptable thermal climate, the first step is to include measures that provide minimization of heat gains.
This paper examines the application of ventilative cooling solutions in cold climates through simulations of an already existing kindergarten in Norway. This kindergarten has a mixed-mode ventilation system integrating mechanically balanced ventilation with natural ventilation from motor controlled windows. In this paper this kindergarten has been analyzed by means of energy use and thermal comfort with IDA ICE program. The validated simulation of the kindergarten has been compared to simulations of the same kindergarten using DCV and VAV (both without cooling) and hybrid window ventilation and exhaust fan and only window controlled natural ventilation(these two last with night set back allowed). Results show important energy savings when using ventilative cooling as outcome of the low outdoor temperatures and the same applies for night cooling. Simulation results indicate that solutions like hybrid could cut the annual energy consumption by as much as 13 % compared to conventional mechanical ventilation. When looking at the thermal environment and indoor temperatures, it is found that for really warm days, it is hard to sustain acceptable temperatures without the use of night set back or mechanical cooling otherwise. Ventilative cooling is proven to be relevant to highly occupied buildings and will be crucial to achieving energy targets for renovated or new zero energy buildings while the indoor climate is maintained.

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