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N.B.: The following article basically corresponds to [Steinmüller 2008, p.37-40, “Early Lessons - The Philips Experimental House]
Triggered by the first oil crisis in 1973, Philips set out to evaluate potential business opportunities especially with respect to components conceivable in the context of its core in-house technology, such as solar collectors, heat pumps, heat recovery units and other innovative energy supply devices - i.e. mainly “active” components. For a sound assessment, however, it appeared necessary to gain a deep understanding of the overall system - including the “passive” behaviour of the building under various climate and usage patterns. As a consequence, in 1974 the project “Rationelle Energieverwendung und Nutzung der Sonnenenergie in Gebäuden”, the so-called “Philips Experimental House Project” was launched. Here, the Philips Experimental House was primarily meant to serve as an experimental test-bed for the derivation and calibration of computer-based models, which then would enable a rigid, experimentally validated analysis of relevant system parameters under a wide set of different boundary conditions in the Western World. The project and the following research were inspired by Scandinavian work on low energy houses, as well as American efforts on passive solar buildings and renewable energies (cf. e.g. Korsgaard 1976, Balcomb et al. 1977, Lovins 1977. Interestingly enough, efficiency strategies for electrically operated homes served as another initial input (cf. Stoy 1973 and Hörster 2007). The main measurements were performed in the time frame 1975 - 1978. Main modelling work was carried out in the years 1977 - 1982. The project came to an end in 1983/84.
|Figure 1: The Philips Experimental House: Test-Bed with Passive House Features & Starting Point for World Wide Parameter Studies|
The experimental house (see Hörster et al. 1980, Fig. 1) was an upgraded off-the shelf prefabricated wooden frame house inhabited by a computer and equipped with super insulation, the best obtainable windows at that time, controlled ventilation with 90% heat recovery and two soil heat exchangers (one of them a porous wall for pre-conditioning fresh air, the other one a collector feeding the heat pump). The computer (located on the roof floor) steered the experiments, collected data in minute-intervals and simulated the living of a family of four on the ground floor. The resulting heating requirement ranged between 20 and 30 kWh/m2a - i. e. more than a factor of 15 below the demand of normal houses at that time, close to what a German passive house would need today. In fact - apart from the windows, which were not available, but under research and beginning development at that time – the house already showed all of the properties a modern passive house is known for. Besides, the small remaining energy demand could largely be covered by renewable energies (such as solar thermal energy supplied by own experimental vacuum collectors and heat pumps in the cellar) demonstrating basic techniques for obtaining net zero energy.
Based on the experimental data obtained, a wide range of computer-based models was derived in the sequel, which enabled system and component analysis in fine-grained and coarse-grained resolution, model-experiment and inter-model validation as well as system and component simulation under a wide variety of boundary conditions. Thereby the focus was on year-round results under real climate and user patterns, as they determine overall energy use and customer choices. It turned out, that with hourly changing boundary conditions mapping building dynamics onto a single thermal capacity renders sufficiently fast, accurate models needed for performing the year-round computer-experiments. On this basis extensive studies including the US & Europe where performed (see e.g. Bruno & Steinmüller 1977, Bruno & Hörster 1978, Steinmüller & Bruno 1979, Steinmüller 1979 – 1982).
As an example, Fig. 2 shows an original output of one of the studies (Steinmüller 1979) displaying the annual heating requirement of three basic house types “Experimental” (super-insulated similar to Philips Experimental House), “Swedish” (insulated according to Swedish building codes) and “Normal” (poorly insulated <but new!> German building at that time) in light (E, S, N) and heavy (EH, SH, NH) versions in 4 European and 4 North American climates. Accordingly, with respect to “Normal” houses, it was possible to reduce the heating requirement by a factor of 10 to 20 in all climates simply by improving the passive characteristics of such a house. In fact, it appeared that in most climates these efficiency measures are much more effective than measures on the supply side (cf. Bruno & Hörster 1978). Thus, the paradoxical result - for a company which set out to exploit the supply side potential - was that demand side measures should receive top priorities
Note, these conclusions included old buildings as well, where considerable saving potentials were seen and saving measures suggested (Hörster et al. 1980:188 ff). Analysis of eco-efficiency in terms of “price of the energy unit saved” (cf. section 2.2.2 and Hörster et al. 1980:153ff)showed that for Central-European climate conditions (Hamburg), depending on the heating system employed factor of 5 to 20 reductions also appeared economically feasible. Basically that has not changed until today (2012) – but, the energy prices are much higher now, resulting in even better economical results for the passive components.
Actually, it became clear that houses could be run without conventional heating systems so that corresponding internal research on small auxiliary heating devices was started.
As windows appeared as the weakest components and as passive solar heating was under intensive discussion, window systems received particular attention. Highly efficient translucent walls (Bruno et al. 1979) reaching thermal parameters comparable to current passive house windows were shown as a possible solution. Simulation experiments measured the impact of window parameters under various climates (see Fig. 3, Steinmüller 1979 and 1982). It turned out that in Central and Northern Europe, window areas beyond 30 – 50% of the South façade do not lead to additional gains in well-insulated houses – which is consistent with later recommendations for the optimum dimensioning of windows in passive houses (Feist et al. 1994). On the other hand, in climates as in Albuquerque a broad range of passive solar options turned out feasible even with relatively simple window systems (compare that results to Feist/Schnieders et. al. 2012).
In a study on the unitary heat pump market in the US (Bruno & Steinmüller 1979) isolines were calculated for the US, showing locations of equal heating, resp. cooling requirement as well as maximum design load. This study performed for single family homes with about 160 m² floor area showed, that improved insulation standards can reduce heating and cooling loads down the order of 10 W/m2 - i.e. exactly the levels typical for a Passive House - where they may be met with a single unitary heat pump device, i.e. a very simplified heating system. This again exactly is the core principle of the Passive House, proven valid now in ten thousands of realized projects.
|Figure 4: Implications for the Size of Heating and Cooling Systems in the US: Small “Passive House Systems” in sight with Philips Experimental House Standard|
Altogether, basic lessons concerning technical and economic trade-offs between active supply side and passive demand side measures have been learnt and the feasibility for highly energy efficient sustainable housing was established for various climates in the Western world. In particular, fundamental insights concerning the worldwide relevance of passive techniques have been gained. For these achievements the Philips-Team Dr. Günther Bergmann, Dr. Richard Bruno, Dr. Wilhelm Hermann, Dr. Horst Hörster, Dr. Reinhard Kersten, Ing. Klaus Klinkenberg and Dr. Bernd Steinmüller were honored with the „Passive House Pioneer Award” in 2012. Bernd Steinmüller has re-embarked on efficient housing research in 1997 and continues pioneering and expanding the original ideas worldwide.
N.B.: The following bibliography basically is an extract from [Steinmüller 2008, p.123ff] supplemented with some more recent references.
References Philips Experimental House Research 1974ff
References B. Steinmüller 1998ff