How TBDA Uses Passive House To Design Better Buildings

December 6, 2019 | Tom Bassett-Dilley

Passive House is more than an energy standard—it’s a way of understanding the technology of high-performance building, and it allows architects to optimize a building’s performance through the design process, regardless of whether an owner wants to pursue certification or not.

The “business-as-usual” approach to design is to focus on program and appearance, then have an engineer or contractor size mechanical systems to condition the building; more sensitive designers may take into account sun angles and daylighting, but for many designers these are afterthoughts as well. That approach usually leads to needless energy consumption, glare, overheating, and thermal bridging. Our approach is to use the powerful Passive House modeling tool to tune the building to the climate as an integral part of the design process.

We begin design with an analysis of climate (temperatures, humidity, sun, rain/snow, wind), vistas and sense of prospect or “belonging” on the site, topography, and neighborhood or natural setting, all to allow the building to speak the language of the site. I think of it as imagining a living thing that evolved to live in that place—its feet or roots in the ground, its back to shelter, its face to the sun, with the right brows, whiskers, or foliage, as the metaphor may be!

That leads to initial gestural designs that become building shapes. As soon as we settle on a general layout, we then bring that geometry into our Passive House (PHIUS) modeling software (called WUFI-Passive), where we can enter values for insulation, window size, orientation, and performance, mechanical system performance, and internal energy use. By trying out different values for these, and by trying different approaches to shading and exposure, we can arrive at an optimal performance level for the building.

Part of the beauty of the PHIUS standard is that the climate-specific metrics give definite targets to design toward. When we optimize for both heating and cooling loads, we set the stage for comfort; when we minimize overall energy (efficient mechanical system, lighting, and appliances), we can design a project to meet annual net zero energy with the smallest solar PV array possible. And from a design point of view, we know the building will have a climatic “fit” that will allow the building to feel true to place.

If there’s one absolute I go by, it’s that Nature is right. I use the PHIUS tools and knowledge to allow my designs have an organic approach to energy, just as I employ biophilic design and understanding of the locality to allow the designs to have an organic, natural countenance and fit with the site. We’re pursuing ecological architecture through both art and science.

Tom Bassett-Dilley Architects | Contact