A Different Approach to Building Science

Passive House

Passive House | Ellison Building | Cape Fear, NCPassive House is simply the most rigorous energy efficiency standard on the planet today. Passive Houses use 70% less energy while providing superior comfort and indoor air quality. How is that possible? There are seven concepts that make up the Passive House standard.





Just like a thermos, Passive House are packed with insulation to keep the heat OUT in the summer and IN during the winter.

[Photo:  A combination of expanded polystyrene and cellulose to form a super-insulated wall]




Debunking the myth that houses need to breathe, Passive Houses are super tight to keep moisture and air from moving through the building envelope.

[Photo: High performance caulk is used to seal the seams of the wall-to-roof juncture]




Breaks in the insulation layer usually caused by structural elements and utility penetrations in the building envelope create a “thermal bridge,” allowing undesirable exterior temperatures to migrate into the home.

[Photo: This concrete beam is an example of a thermal bridge]





Usually a weak point in the home’s insulation layer, Passive House windows have well-insulated frames, triple paned glazing, and high solar heat gain coefficients on south-facing windows to help save energy.

[Photo: The profile of a thermally broken window frame]







Because Passive Houses are so airtight, they need mechanical ventilation to breath. An energy recovery ventilator is a high tech piece of equipment that brings in a constant stream of fresh air while exhausting stale air from inside. The amazing part is that it can recover up to 95% of the heat from the exhaust stream, and transfer it back to the fresh air stream.

[Photo: Energy Recovery Ventilation diagram]




A big source of heat in a Passive House comes from the sun, so orienting the house with sun in mind is important. It’s amazing to think that heat from appliances, lights, people, and the sun is almost all you need to keep warm in the winter. But it’s just as important to keep the sun out in the summer. Shading is critical in a Passive House.

[Photo: Passive Houses utilize winter sun and block summer sun]




The Passive House Planning Package (PHPP) is a tool used to accurately assess energy modeling of a building that accounts for attributes such as airtightness, insulation, and solar orientation. Only when a building meets the following measurable requirements is the Passive House standard met: heating requirement of less than or equal to 4.75 kBtu per sq. ft. per year, energy use of less than or equal to 38 kBtu per sq. ft. per year, and airtightness less than or equal to 0.6 air changes per hour (ACH) at 50 pascals (Pa).

Ellison Building Company is the only builder in southeast North Carolina qualified to construct Passive Houses. After completing a rigorous training course and passing several exams, Ellison received the rare Certified Passive House Consultant designation from the Passive House Institute US (PHIUS). This designation ensures that the seven concepts of Passive House come together to form a complete energy efficient building system.