Abrams Design Build Announces Passive House Consulting Services

With energy costs soaring and an increased awareness of the effects of climate change we must demand more effective solutions for energy efficiency and better indoor equality in our homes. Passive House design provides a way for us to attain not only these goals but also true carbon neutrality. The Passive House energy modeling software has a feature that shows the calculations for CO2 emissions used and conserved. The Passive House concept represents today's most stringent energy standard with the promise of slashing the heating energy consumption of buildings by 90%. Overall energy usage, known as primary energy, has been shown to decrease by 75%.

At this time there are around 200 Certified Passive House Consultants in the United States and Alan Abrams, CAPS, CPBD, CGBP, CPHC - Owner is a Certified Passive House Consultant. He can help you with strategies that apply the Passive House principles to your dream home. All the services that we offer, design and build of new homes and additions, and retrofits of vintage homes as well as energy audits and consulting can be approached from the Passive House principle. Let's talk!

What is a Passive House?

A Passive House takes into account the free heat gained from the sun and "internal heat gains" from people and appliances. It is a very well-insulated, virtually air-tight building. Avoidance of heat gain through shading and window orientation also helps to limit any cooling load. A Passive House is a comprehensive system. Working with natural resources, free solar energy is captured and applied efficiently, instead of relying predominantly on ‘active’ systems to bring a building to ‘zero’ energy. High performance triple-glazed windows, super-insulation, an airtight building envelope, limitation of thermal bridging and balanced energy recovery ventilation make possible extraordinary reductions in energy use and carbon emission.

The Passive House System was developed in Germany, where it is called "Passivhaus", in 1996 by physicist Wolfgang Feist. Feist was influenced by the groundbreaking, superinsulated houses that were built in the US and Canada in the 1970's. His cause was championed by German born Katrin Klingenberg, who founded PHIUS - Passive House Institute United States.

At this time there are over 20,000 Passive House buildings in Europe. Although there are only 2 dozen Passive House buildings in the U.S. many more are in the planning stages because of increased demand due to skyrocketing energy prices.

What are the requirements for a Passive House?

The requirements for a Passive House are, though simple, very strict. In fact, the three requirements for Passive House are more strict than the International Residential Code (IRC) and the Energy Star Program. The three requirements are as follows:

• Air Infiltration - no greater than .6 air changes per hour (ACH) at 50 pascals (IRC is 7 ACH, Energy Star is less than 5 or 6 ACH)
• BTU Consumption for heating and cooling uses - cannot exceed 4755 BTU per sq. ft. (= 1.39 kWh per sq. ft.) annually (IRC average is up to 10 times, Energy Star up to 8 times)
• Energy Usage - total usage (also known as Primary Energy usage - which includes all appliances) cannot exceed 11.1 kwh per sq. ft. - or 38039 BTU/sf/year (Estimates approximately put usage for IRC at 30 kwh per sq. ft. and for Energy Star at 20 kwh per sq. ft.)
  

A Passive House project begins with the use of proprietary energy modeling software which takes into consideration weather patterns and the climate zone of the building site, solar orientation, type of building materials used and other criteria. The Passive House standard is based entirely on performance - if it meets the standard it is considered a Passive House.

What is the process to certify a Passive House?

Pre certification of a Passive House begins at the planning stage. With the energy modeling software, Passive House Planning Package (PHPP), specifications are reviewed for any errors. After the house is built but before walls are insulated multiple blower-door tests are performed to ensure the Passive House standard is met for air tightness. If any fixes are needed more tests are performed.

It is important to gather a team together from the start. Communication between the consultant, architect, contractors, and engineer is critical. Before construction begins, plans, details, and the PHPP file is submitted to PHIUS. Upon review and approval, construction begins. Before the interior finishes are applied a blower door test is administered to ensure the air tightness of the envelope. It is important to do a blower door test before the final finishes are installed to fix any leaks.

Contractors are required to submit "as-built" photos to PHIUS to show that the house was built according to the agreed upon specifications. Also, the contractor must submit a declaration that guarantees that the house was built as planned and that the mechanical systems are installed as specified.

Lastly, a final blower-door test is performed, if the Passive House standard of 0.6 air changes per hour (ACH) is met PHIUS issues a certificate stating that the building is a Passive House. Achieving a Passive House not only means you have much lower energy usage (and lower bills), but also healthier indoor air quality (due to a known quantity of filtered air circulating through the building, instead of seeping in through the dusty cracks). Because of higher quality windows (with insulated frames) drafts are minimized, no more cold spots by the windows. For this reason, a Passive House is a comfortable house.

*Much of this discussion owes a debt to the article The Passive House: Green Without Gizmos by Jefferson Kolle in Fine Homebuilding Magazine issue #210
*with input from Keihly Moore - designer, consultant in training