PR2014

The GK environmental house is the first office building in Norway built according to the passive house concept. In such buildings, it is crucial to develop a ventilation strategy to reduce the energy use outside of the operating time. An optimal operating strategy has been developed for cold days, when the outdoor temperature falls well below 0 °C, which is presented in this paper. Indeed, these conditions correspond to the largest heat loss.

The impact of over-tempered air on the perceived indoor climate was evaluated by questionnaires filled in by the users of the first office building with passive house standard in Norway. In this building, the heating demand is covered entirely by warm air supplied into the rooms through the ventilation system.

The Kindergarten Solhuset is built according to the Active House vision with an emphasize of good daylight conditions and fresh air. The house was completed in 2011, and detailed measurements of the indoor environment have been performed since the completion. The daylight performance is evaluated with daylight factor simulations. The main activity rooms have daylight factors of 7%, while the innermost rooms with only roof windows achieve a high daylight factor of 4%. Electrical light is used frequently in daytime during the winter, but much less frequently during summer.

The present paper addresses experiences with ventilation and thermal comfort in the Active House concept, based on the Active House Specification and realized Active Houses. The Active House Specification is based on a holistic view on buildings including Comfort, Energy and Environment. It uses functional requirements to indoor air quality and thermal comfort. Experiences from realised Active House projects show that better airtightness than nationally required has been achieved.

The thermal comfort of the residential buildings Sunlighthouse in Austria and LichtAktiv Haus in Germany are investigated with a particular focus on the summer situation and the role of solar shading and natural ventilation. The houses have generous daylight conditions, and are designed to be CO2 neutral with a good indoor environment. The thermal environment is evaluated according to the Active House specification (based on the adaptive method of EN 15251), and it is found that the houses achieve category 1 for the summer situation.

The Marienlyst School is the first educational building in Norway built according to the passive house standard. This building benefits from a super-insulated and airtight envelope. While this reduces the heating demand largely, it also enhances the risk for poor indoor air quality and overheating compared to conventional buildings. It is therefore particularly important to implement an efficient ventilation strategy in order to avoid adverse effects on the health, well-being and productivity of the pupils.

An inherent element of the passive house is the system of exhaust ventilation in air supply. According to their class, air filters used in ventilation systems stop the contamination, but may also be the main source of secondary indoor contamination during long-term use.

Demand controlled heat recovery ventilation systems, which combines heat recovery (HRV) and demand controlled (DCV) is growing fast among ventilation manufacturers.

Several categories can be identified, from global dwelling regulation, to fine room-by-room regulation of the airflow rate. Simulations show that room-by-room demand controlled heat recovery ventilation is the best compromise to optimize at the same time indoor air quality, comfort, and energy savings.

In this article we compare to ventilation strategies to heat a “passive house” office building using only the ventilation system. Two ventilation strategies with supply air temperature above and below the current room temperature were compared through a cross over experiment. A questionnaire was used to measure the perceived health and well being. Both strategies documented very good indoor climate with highly positive scores on the questionnaire.

Increasing airtightness and isolation of residential buildings in today’s climates cause challenging situations for the summer indoor climate. In combination with ventilation for fresh air, it calls for intelligent control of passive cooling when available, and active cooling when needed.

The combination of heat recovery ventilation and an air-to-air heat pump cooling system is a solution to these challenging situations. With the exhaust air heat pump cooling system, heat is transferred from the supply air (which is getting colder) to the exhaust air (which is getting warmer).