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Since 2003, most European countries established heat health warning systems to alert the population to heat load. Heat health warning systems are based on predicted meteorological conditions outdoors. But the majority of the European population spends a substantial amount of time indoors, and indoor thermal conditions can differ substantially from outdoor conditions. The German Meteorological Service (Deutscher Wetterdienst, DWD) extended the existing heat health warning system (HHWS) with a thermal building simulation model to consider heat load indoors. In this study, the thermal building simulation model is used to simulate a standardized building representing a modern nursing home, because elderly and sick people are most sensitive to heat stress. Different types of natural ventilation were simulated. Based on current and future test reference years, changes in the future heat load indoors were analyzed. Results show differences between the various ventilation options and the possibility to minimize the thermal heat stress during summer by using an appropriate ventilation method. Nighttime ventilation for indoor thermal comfort is most important. A fully opened window at nighttime and the 2-h ventilation in the morning and evening are more sufficient to avoid heat stress than a tilted window at nighttime and the 1-h ventilation in the morning and the evening. Especially the ventilation in the morning seems to be effective to keep the heat load indoors low. Comparing the results for the current and the future test reference years, an increase of heat stress on all ventilation types can be recognized. [ABSTRACT FROM AUTHOR]

Abstract: Monitored data from a low exergy building at Wentzinger Hof Freiburg was investigated for optimal energy operation. The first step was the investigation which involved the sub-division of building envelope into four balance boundaries and each boundary consists of its own active components such as geothermal bore well system, reversible heat pump system, buffer storage, heat exchanger and distribution system. The purpose of the analysis was to refine the monitored raw data to calculate the thermal energy consumption, auxiliary energy consumption and performance along the balance boundaries. The second step was the optimization and rating of the building envelope. The analysis yielded the performance and energy consumption for each boundary level. It was suggested from the optimization analysis that a considerable amount of energy can be saved through the optimized control strategies of active components, seasonal dead-band control and the operation of buffer storage. [Copyright &y& Elsevier]

In designing an earth-to-air heat exchanger (EAHX), a decision on design goals has to be made. If the air flow is given by the ventilation system and the construction site is known, the question is: is it more important to achieve a high specific energy performance based on the surface area of an EAHX, a high adoption of air temperature to ground temperature or a very small pressure loss? This paper deals with the performance of three EAHXs for mid European office buildings in service, with the aim of characterising their efficiency. A general method to compare EAHXs in operation will be introduced. First, the temperature behaviour is described by plots over time and characteristic lines, and compared by standardised duration curves. Second, the energy gain is illustrated by standardised graphs. Third, a parametric model is used to provide general efficiency criteria. Thermal efficiency should be defined by both the dynamic temperature behaviour and energy performance. [Copyright &y& Elsevier]

The current methods used to assess the energy performance of ventilation devices do not consider all the aspects necessary for a comprehensive evaluation of decentralised ventilation concepts and can only be partially adapted to their needs. In order to improve the energy evaluation and to ensure the comparability of different systems, a calorimetric method was developed and implemented in test facilities for the evaluation of two decentralised devices: one equipped with a recuperative counter flow heat exchanger and one with a regenerative heat exchanger. This method, based on direct measurements of the heating load in an insulated test room, includes the effect of the electrical consumption of the fans on the energy performance of the ventilation devices. The calorimetric evaluation method was extended to a seasonal evaluation on the basis of a heating-degree-day method implemented for a warm, a cool and a moderate location in Europe: Athens, Strasbourg and Copenhagen. All the results are above 50% efficiency for both devices, even in Athens where the use of heat recovery ventilation is not usual. [ABSTRACT FROM AUTHOR]