We finally had the chance to test DesignPH, the SketchUp plug-in that allows you to carry out the preliminary design of passive buildings in 3D. Once the model is created, you can export the data to PHPP (the energy balance software for passive house design), to further the energy design in depth.
Even though this plug-in has been available on the market for a couple of years, since version 8.5 of PHPP, our recent meetings with passive house professionals tell us that this tool is not yet very widespread. It is the case of Italy, as well as the impression we got from our recent trip to the USA.
For this article, we tried to model one of the two passive houses that we are currently building in Cavriago, Italy, to analyse the pros and cons of this software.
I remember quite clearly the first time I opened the PHPP: it was version 6, and my immediate reaction was: “what in the world am I doing?”. As an architect, I’ve always felt the need of a visual support to my work. For sure, I feel much more comfortable sketching ideas rather than filling out endless Excel tables. And yet, up until now, passive house design has been dominated by tables and numbers.
In this Excel-dominated context, DesignPH seems a bit like a dream coming true: via an easy and intuitive tool such as SketchUp, this plug-in allows you to carry out the early design, developing at the same time the architectural concept as well as the energy one.
Anyone involved with high-efficiency buildings knows how much the early architectural design phase influences the energy efficiency of the future building, because it shapes its thermal envelope.
Once you get started with the software, the first steps involve modelling the thermal envelope of the building, and optimising it as far as orientation, compactness, distribution of openings and so on.
In the second phase, you need to assign physical properties to the elements you created: walls, roof, openings can either be customised, or imported straight from the database of certified components of the Passivhaus Institut.
It is not necessary to model the internal partitions of the building, whereas external elements need to be modelled if they cast shadows on glazed openings. Non-heated rooms can be modelled simply by entering a temperature reduction factor.
As the final step, you need to model the surrounding buildings and other elements that can cast shadows onto the building. You can also import an approximate terrain model from Google Earth. After this step, the plug-in is able to assess the shading effect of external volumes onto the thermal envelope of the building, and to calculate the solar heat gains.
As far as climate data, the plug-in is provided with a wide range of data sets: for example, it includes 25 location for Italy. It doesn’t seem to be possible to customise climate data yet.
Once you complete the model, it is possible to run the preliminary energy calculation, to assess the heating energy demand of the building. The calculation run by the plug-is is based on the yearly average, and it does not require any interaction with PHPP in this phase. The results are less precise than a monthly calculation, however the main goal of DesignPH is to optimise architectural and thermal design at the same time.
You should not however be fooled by the user-friendliness of this plug-in: what you get is just a basic assessment. Important aspects of passive house design such as thermal bridges, air tightness, ventilation heat recovery and so on are assumed to be “average” by the software (this data is not entered by the user).
A result of 15 kWh/m2y from DesignPH does not mean that the building you designed is passive: it most likely means it needs to be improved, to allow for some leeway during the following PHPP calculation – which cannot be skipped if you want to build a passive building that actually works.
LANGUAGE, LICENSE, COST
At the date of this article, DesignPH is available in English and German. We don’t know whether or not the developers intend to add more languages in the future.
You can download a free demo version of the plug-in: keep in mind that it was developed for SketchUp v.8, although it is also available for the free versions of SketchUp 2013 and 2014.
The license for DesignPH is sold separately from the one for PHPP: you can purchase them together or separately on the website of the Passivhaus Institut. On the same site, you can also find the most updated price for the current version for both softwares.
Once you have complete the model and run the preliminary calculation within DesignPH, you can export your data as a .ppp file: this can be imported directly into PHPP from version 8.5 on. To our knowledge, it is not possible to import this data in older versions of PHPP.
We did not try and import a 3D model into SketchUp from a different source, such as Archicad or Revit. Even though this is probably possible, our guess it that it is more advisable and faster to model the building from scratch.
We also did not try the opposite – exporting the 3D model from SketchUp+DesignPH: we’ll keep you posted once we do try.
DesignPH is no doubt an important new tool available to designers that work on passive building since the very preliminary phase. The plug-in is extremely intuitive, and perfectly integrated with SketchUp. Exporting data to PHPP is easy, and the overall workflow is much more fluid than PHPP alone.
With this tool, even designers that don’t have a strong energy background are able to optimise their architectural design, to achieve passive house standard.
On the other hand, it would be silly to assume that a simple SketchUp plug-in can be enough in the process of designing and building a passive house. After this preliminary design, further steps are needed, including PHPP calculation, as well as state of the art construction quality.
With DesignPH, and with more and more products suitable for passive house available on the market, this comfort and energy efficiency standard can be finally be made available to a broader base of architects and designer, to become more and more widespread around the world.