Henrik Brohus

Modelling air infiltration due to wind fluctuations—a review

Abstract Wind-induced air infiltration is caused not only by the average wind velocity but also by the turbulent wind fluctuations. This paper discusses the importance of considering the fluctuations when the air flow rate is predicted. The features of turbulence are outlined and a review of existing fluctuating infiltration models is performed. Finally, important areas of future research are identified.

Measurements of Hybrid Ventilation Performance in an Office Building

Abstract This paper focuses on hybrid ventilation performance in an office building. It presents measurement results from the new headquarters of the company Bang & Olufsen, which served as one of the case study buildings in IEA ECBCS Annex 35. Ventilation and control strategy, as well as operational experience of the hybrid ventilation system is presented. Measurement results include long-term values of temperatures, CO2 and energy use for assisting fans and heating of ventilation air as well as electricity use for appliances. They include short term values of thermal comfort, temperature distribution in selected parts of the building, CO2 levels, and various tracer gas measurements for examining ventilation effectiveness, air and contaminant distribution, multizone internal air flows and air flows between the building and the outside environment. Results show an office environment with an acceptable thermal comfort level and a high level of IAQ, but with relatively high energy use for heating. The ventilation principle works well with high ventilation effectiveness when the system is operated.

An Iterative Assessment Concept for Building Design Based on the Eco-factor

Abstract Problems in office buildings are often related to the design and control of the indoor environment and of the building as an energy system. The often interconnected nature of the above two issues is important to take into account, since, for instance, internal and external heat loads, temperatures, and air change rates affect both energy use and indoor comfort. Thus, to avoid the indoor climate problems, it is essential that energy optimisation is integrated with assessment of indoor climate. An assessment concept based on the so‐called Eco‐factor has been developed; it can assist building designers in creating solutions of these problems. The assessment concept is meant to be an integral part of new design guidelines for office buildings, which aim to achieve energy efficient buildings with a good indoor comfort and low environmental impact. The building designers have different needs at different stages of the design process. For this reason, the assessment concept makes use of the Eco‐factor t...