Every project we work on strives to be as sustainable as possible within the parameters we are given. This means we are continually looking for opportunities to specify sustainable materials, lower energy and water usage, and reduce waste. We consider things like lifecycle costs and carbon emissions as we make decision decisions and guide our clients through the design process.
With sustainability as one of our core values, clients often ask us about certifications such as LEED, Earth Advantage, Living Building, or Passive House. In this post we will discuss Passive House and whether it is right for your custom home project.
Passive House standards are a set of design principles based on building science, that lead to a quantifiable level of energy efficiency. Using passive design strategies and active systems that are tailored to your specific climate and the design of your home, we can create a comfortable place to live while minimizing energy usage. To achieve this, Passive House design and construction follows theses five principles:
Employ continuous insulation throughout the entire envelope without any thermal bridging.
Create an extremely airtight building envelope, preventing infiltration of outside air and loss of conditioned air.
Manage solar gain with high-performance windows and doors (double or even triple-paned windows depending on the climate) in order to take advantage of the sun's energy for heating purposes in the cool fall and winter months and minimize overheating during the warm spring and summer months.
Utilize a balanced heat- and moisture-recovery ventilation (HRV system).
Minimize the space conditioning system.
I have used these design principles to craft projects that have minimal energy usage while being extremely comfortable in all seasons. In fact, a complaint one client had after moving into an ADU we designed, was that the heating system didn’t turn on (meaning the extra insulation we put in the walls prevented the home from ever getting too cold). This is the type of complaint we actually like getting. The house performed too well for the heating system. I believe strongly in using building science to create high performance architecture, and I make design decisions with that in mind.
For those building a single family home, energy consumption and building performance are important aspects to consider when working through the design process. The orientation of the building, the size and placement of overhangs and shading devices, the amount and type of insulation, and the selection of systems all play a central role in how your project will perform over its lifespan. A small upfront investment can pay itself back many times over through comfortable and healthy places to live and lower energy bills.
The other advantage to Passive House strategies and the reduction of energy usage is to plan for a net zero ready home. By using all electric appliances and systems, and investing in insulation to reduce energy usage, we can easily add solar PV arrays that can more than offset your energy usage. Meaning your house could produce all the energy you use and sometimes even more. This not only saves you money every month, but also helps address climate change by reducing your reliance on fossil fuels.
To help encourage people to pursue higher performance building, and to help shift the industry to create the products and systems needed to achieve these goals, certification systems have arisen to verify that the goals have been achieved. The Passive House Institute US manages the certification process and offers a lot of resources to help design professionals meet their standards, and to educate clients on the benefits of this approach. For custom homes I typically don’t recommend actually pursuing certification. Rather than spend the extra money and time working through the certification process I recommend investing in better systems or adding a solar array to your project. However, for some clients having that certification is an important step proving how their home will perform.
Whether certification is pursued or not, our designs strive to meet the performance criteria laid out by PHIUS. We believe it is the right approach to designing better buildings and giving our clients healthier and higher performing homes to live in.
You can learn more about Passive House here: https://www.phius.org/
An Accessory Dwelling Unit under construction. We wrapped the entire structure with 2” of rigid insulation and 3” of rigid insulation on the roof. The continuous insulation has no thermal bridging and creates an tightly sealed envelop preventing loss of conditioned air. Radiant floor heating is the only space conditioning system and rarely turns on. An HRV allows for fresh air to circulate without losing heat energy.