Design passive houses

[CristianoR]

Does Home Designer give specific support for the creation of passive house designs?

[Houska]

To a limited extent. My answer is for Home Designer Pro; some of these may be hobbled in the cheaper versions.

 

Passive house designs generally include carefully designed, multi-layer and thick wall assemblies, containing plenty of insulation. HDPro allows you to create complex custom wall types which allow you to model, for instance, double framed walls, including with an insulation gap in between them. And/or rigid insulation outside the main layer(s) to address thermal bridging. Or a single-framed main wall layer with Larsen trusses on the outside to hold extra insulation. In addition, double frame walls can be specified with a custom framing interval and to alternate studs between layers, also important for avoiding thermal bridging.

 

There is (limited) support for recessing windows and/or doors to the main layer or the sheathing layer (but not finer granularity than that). If this is important to you, do a trial run with your wall assembly, including your choices of what of the wall layer sandwich is in main layer vs on its inside/outside, since that will determine where HDPro allows you recess doors and windows to. 

 

Trusses can be specified with an energy heel, and ceiling planes can be (manually) created some distance below a roof plane to model a sloped cathedral superinsulated ceiling/roof sandwich.  However, again the ability to specify insulation specifics in detail is limited. This also affects foundation modeling, where rigid insulation under a (slab) foundation and/or around stem walls can be modeled manually, say using supplementary slab or soffit objects with insulation material type, but this is not automated.

 

Another important component of passive house design is careful attention to air tightness and, more generally, uninterrupted air, water, and vapour barriers. While HDPro allows you to include a membrane as a wall layer, it does not help display or model to comprehensive barrier envelope.

 

Finally, passive houses make extensive use of passive solar. Through the use of the sun angle feature, HDPro allows good modeling of how far the sun will penetrate at what time of year, adjusted for location.

 

Bottom line in my experience is that HDPro provides enough tools to adequately represent a passive house design and test out the space-planning implications of passive design principles as you work through a design. But HDPro does not have specific support for making a quality passive house.