Parameter study on passive building concepts and their effects on indoor climate, active conditioning systems and the use of grey energy in office buildings

By optimizing passive measures - thermal mass, high insulation standard, reduced proportion of window area, optimized and controlled natural ventilation - energy-efficient office buildings can be implemented without active systems for heating, cooling and ventilation and without compromising comfort. Examples such as office building 2226 by "be achitekten" in Lustenau or the new Ricola building by "Herzog & de Meuron Architekten" are designed and operated on this basis.

These buildings are basically to be regarded as prototypes. Proof of functionality and a generally valid transferability are not given. The aim of this research project is to identify the potentials and limits of passive concepts by means of a parameter study. The mentioned examples show that an optimization of passive building strategies entails an increased demand for materials, of which the amount of grey energy is to be discussed. General recommendations for action are derived from the results of the holistic approach.

The optimization of building envelopes and standards in the building materials industry allows an improvement of passive building concepts and questions the currently practiced measure and procedure regarding active technical systems for room conditioning. The installation of building services as an answer to problems of energy efficiency, comfort and flexibility of use, increases the complexity of the building and is increasingly being questioned under the above-mentioned optimisations of envelope constructions. Generally valid, transferable statements regarding the effects of concepts, such as the example of Building 2226 regarding winter and summer comfort, use of grey energy for the construction up to the consequences of temporary load peaks, are missing in the current discussion. First, the study identifies the decisive parameters and dependencies and determines the criteria to be evaluated. Using dynamic simulations of indoor climate, with interfaces to daylight observation and evaluation of grey energy in constructions, results are generated, analysed and evaluated. The simulation results show which indoor climate conditions arise depending on different façade, natural ventilation strategies and occupancy scenarios, how great the flexibility of low-tech strategies is for use and which façade standards influence user comfort and the level of grey energy. In addition, interfaces to sensible active conditioning systems are identified and recommendations for action are derived.

The study considers passive building measures at the interface to active building services for heating, cooling and ventilation and validates the concepts under holistic aspects. These aspects include natural ventilation strategies, influence of room geometries and occupancy densities, thermal storage masses in the room or the use of grey energy in the construction. In addition to these parameters, user behaviour is also considered.

As a solution to the problems, dynamic simulation models are being developed which, in addition to thermal behaviour, also depict the interfaces to the use of daylight and grey energy. Simulation models, procedures and results will be discussed in planned workshops. By directly bringing in practical experience, a quick implementation in planning and construction industry is aimed for.

The aim is not only to identify the decisive parameters for low-tech buildings, but also to show their influencing factors and dependencies.