I recently embarked on a special training to become a Certified Passive House Consultant. I am finishing up the requirements, but thought it would be interesting to share some of the things I have learned along the way.
Based completely in building science, the Passive House standard is a huge step in the right direction when it comes to building durability and sustainability. Passive House is on the cutting edge of super insulated, extremely air tight building construction. The standard is location specific, and carries weight in the residential, multifamily, and commercial markets.
Credit: http://www.phius.org/phius-certification-for-buildings-products/case-studies/rmi-innovation-center
Here are some points about the Passive House Institute United States standard:
Credit: http://www.phius.org/become-a-professional/certified-passive-house-consultant-cphc-training/program-overview
- Passive House US is climate specific
- 1000 different data points throughout the United States are used to create the appropriate “limits” of energy consumption and are the basis for the Passive House Standard in the building’s specific location.
- These limits create challenges for designers,
but really benefit the end user of the space up front and over time.
- More insulation, and air tight assemblies are challenging for the design and construction team, but the mechanical systems are much smaller and simplified.
- “Air tight” construction requires mechanically ventilating
spaces using efficient Energy Recovery Ventilators.
- Mechanical Ventilation allows control of incoming air, and filtration of airborne contaminants among other positive ventilation controls.
- “Super insulated” construction means that there
will be more consistent temperatures throughout the day and night, and less
load on a heating or cooling system.
- The systems can therefore be downsized, saving money on initial costs, and life cycle costs for running the heating and cooling over time.
- Building geometry is very important when
designing energy efficient structures.
- More efficient structures have less corners, jogs and odd angles, allowing insulation and air sealing to be continuous.
- Thermal bridge free design, or paying close
attention to building envelope breaks, penetrations and wall and floor
junctions is important to keep cold temperatures from moving though our
well-designed envelopes.
- The first reason is that when warm moist air passes over cold objects, the moisture is released, and condenses on the cold object as liquid water. Liquid water can cause mold growth, and decomposition of building materials.
- A large thermal bridge can also transfer temperature from the outdoor to the indoor environment and create cold areas in the room. Uneven interior temperature and particularly cold spots puts extra strain on the heating system and creates uncomfortable drafts.
- When creating a super insulated assembly,
windows then become the weak point in a wall.
- Paying attention to solar orientation can greatly impact a buildings energy usage.
- Using windows with appropriate solar heat gain coefficients are very helpful when designing for solar gain in the winter, especially in heating dominated climates like the Northeastern U.S.
- Shading these same windows is an effective strategy for excluding solar gain in the summer.
- Air tightness is an essential part of any energy
efficient structure.
- In a heating dominated climate like ours, leaky buildings use more energy to make up for lost heat through an assembly.
Credit: http://www.phius.org/what-is-passive-building/passive-house-principles
Beyond the sole understanding of the Passive House standard, designers should always consider these essential points when designing new and retrofitting existing buildings.
My hope in having studied this standard, and learning about building science, passive systems, mechanical systems and thermally improved envelopes, is that I can work more deliberately in this world of Research Based Design, and further STA’s commitment to environmental design.
-Nate
