Passive Houses in tropical climates

Passive Houses in tropical climates

Postby greenbuild » Sat Nov 09, 2013 3:33 pm

The studies "Passive Houses for different climate zones" / "Passive Houses in tropical climates"
extracts from the Passive House Institute
of the connected studies Passive Houses for different climate zones and Passive Houses in tropical climates)


The authors wish to thank the Deutsche Bundesstiftung Umwelt and Saint-Gobain CRIR for their financial support and valuable input in this research project.

The building sector makes up a large part of man-made CO2-emissions released into the atmosphere. The upside of this problem is that energy savings from the heating and cooling of buildings have the potential to effectively reduce emissions of heat-trapping gases. The Passive House Standard for buildings can play a crucial role towards this goal.
In countries like Germany, it has been demonstrated that Passive Houses make do with around 80 percent less heating energy than current new buildings do. The studies Passive Houses for different climate zones and Passive Houses in tropical climates now focus on transferring the Passive House concept to fundamentally different climates.
The first, very successful Passive House projects in Germany were built only after comprehensive, strictly systematic scientific research. In detailed dynamic building simulations, crucial planning parameters and the role of each in the overall system were identified beforehand. As a result, there was a good basic understanding of the thermal response of Passive Houses even before the first pilot project had been constructed. In this way, critical planning errors were avoided from the outset, and the concept quickly convinced a large number of users and parties interested in further developing it.

While pilot projects are currently (2011) being conducted in other climate zones, there is not the same broad basis of practical experience as in central Europe. At the same time, it has not been possible yet to study the underlying principles as systematically and scientifically as it would have been ideal. By investigating example sites worldwide, the studies intend to finally provide a sounder overview of proper approaches to Passive Houses in these areas and determine the influence of individual planning parameters.
The studies are research reports, and while they attempt to provide a solid theoretical foundation along with numerous planning tips, the findings have not yet been reviewed in a wide range of practical applications.

Procedure - The studies' structure

1.) Specification of the locations to be studied and of the climate data employed
2.) Definition of a Reference Passive House for each location
This Reference Passive Houses can be conditioned solely by means of the supply air already needed for indoor air quality. Based on this building, a parameter study illustrates the role that different construction parameters play. The result is a rough estimation of what requires special attention in planning. Up to that point, the architecture has not taken special consideration of the particular location.
3.) Specific local characteristics
This section focuses on a number of aspects that are not as relevant in the construction of Passive Houses in central Europe as they are in other climate zones or that differ fundamentally in other climate zones. Some of these issues concern several of the sites under review here and are therefore discussed irrespective of the parameter studies mentioned above:
Special aspects dealt with in the studies:
Frost-free foundations
Frost protection for ventilation heat recovery
Adapted window qualities
Solutions for high outdoor air humidity in the summer (coming soon)
Solutions for heat and cooling supply in moist-warm climates (coming soon)
Separate cooling and dehumidification (coming soon)
Free-running buildings in tropical climates
Interior insulation in tropical climates
Condensation on exterior surfaces in tropical climates
Mechanical services in tropical climates
4.) Development of building designs for Passive Houses...
…in five specific climates and locations - Yekaterinburg, Tokyo, Shanghai, Las Vegas and Dubai - and presentation of the related concepts, construction component combinations, connection details and energy balances.
5.) Hygrothermal study of the component combinations used
Main focus: Will humidity problems occur in the various climates for the designs proposed (assuming proper installation), such as long-term moisture buildup, mold, and condensation inside the building?
6.) Ways of determining design data for the heating/cooling load and characterization of the most important properties of Passive Houses...
…at various locations around the world based on a database of global climate data.

Main findings

In the studies eight locations in different climate zones were investigated: 01 - Yekaterinburg, 02 - Tokyo, 03 - Shanghai, 04 - Las Vegas, 05 - Dubai, 06 - Singapore, 07 - Salvador, and 08 - Mumbai. It was demonstrated that Passive Houses are technically feasible in all of these locations.
An analysis of globally available satellite data revealed that Passive Houses can be realized with limited heating and cooling outputs almost all over the world. Surprisingly, hot regions (maximum average outdoor temperatures almost never exceed 40 °C, for which components commonly available on the market still managed to suffice) are not the main problem – very cold areas are. Under daily average temperatures down to -70 °C with negligible insolation, external components – especially windows – would have to be customized. Economically, reducing the heating demand down to the Passive House level in extremely cold climates does not currently pay for itself. This fact may be of theoretical interest, but is not relevant for practical purposes because these regions are practically unpopulated.

The tropics are a special case in light of their slight seasonal temperature fluctuations. There, no heating is needed, but annual cooling demand can be great even if cooling loads are small. The economic analysis shows that building standards that go beyond the functional Passive House level are the best economic solution for these climate zones.
In any case, the Passive House concept will have to be adapted to local building traditions, climates, and aesthetics. Hygrothermal calculations show that different construction component combinations will have to be used depending on the location. Designs that have proven useful in a certain climate may be completely unsuitable elsewhere.
It was also found that, apart from the prototype inexpensive row houses, architecturally demanding buildings can also be realized in the Passive House Standard, albeit with more expenditure being required in some cases than with simple buildings with moderately glazed façades. Architectural freedom and design leeway is provided by the Passive House principle, even within building cultures that developed over centuries.
Passive Houses in tropical climates
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