We have been reading about building certifications and trying to understand what is really important. At the end of the day, we are really looking to have a home that keeps itself at 40 degrees in the winter with no or minimal energy use, cover all our electricity with a small solar array (4 to 5 KW system), and provide natural cooling in the summer.
However, the certifications are helpful in that they provide guidance on how to meet energy efficiency and some ways to measure them. Here's some of the certifications/ratings we have been looking at:
Passive House: This one is useful because it is "trendy" and builders and homeowners are publishing a lot of information on the topic. We don't need a certified passive house - but many of the concepts are driving our decisions.
Here's the approach:
Then you measure the results:
HERS rating: This score measures the energy efficiency of a house. A passive house is typically between 20 and 30 without the solar system. With a solar system, you can end up with a negative HERS score.
LEED: This is not worth pursuing. Very difficult and expensive. Lots of paperwork and not much benefit to us as homeowners.
Department of Energy Zero Energy Ready. These programs have some good concepts and we should work toward implementing them in our design. Many Habitat for Humanity homes are featured here as they work to providing efficient homes without the large price tag.
Living Future: A more comprensive view on what makes a home green.
Minnesota Green Path: Should be very simple and cost effective to achieve and would be a good idea to document, since we will do all these things anyway. It's not a very high standard to meet but it sounds good to a future buyer.
Energy Star Homes are not even close to an efficient house. This standard is so low that any house that doesn't meet it should not have been built.
However, the certifications are helpful in that they provide guidance on how to meet energy efficiency and some ways to measure them. Here's some of the certifications/ratings we have been looking at:
Passive House: This one is useful because it is "trendy" and builders and homeowners are publishing a lot of information on the topic. We don't need a certified passive house - but many of the concepts are driving our decisions.
Here's the approach:
- Super insulate
- Eliminate thermal bridges
- Create a building envelop that is infiltration-free through airtight construction
- Provide proper ventilation by specifying energy or heat recovery ventilation
- Specify high-performance windows and doors
- Optimize passive-solar and internal heat gains
- Model energy gains and losses using the Passive House Planning Package (PHPP):
Then you measure the results:
- Air infiltration: The Passive House standard for air infiltration can be no greater than 0.6 air changes per hour (ACH) at 50 pascals, which means the house is virtually airtight. The IrC’s current energy code requires 7 ACH at 50 pascals. energy star requires less than 5 or 6 ACH, depending on the climate zone.
- BTU consumption: The annual energy use for heating and cooling can-not exceed 4755 Btu per sq. ft. annually. The average new home built to current code consumes nearly 10 times that amount. energy star has requirements for appliances and mechanical systems that can still amount to nearly eight times the Passive House requisite.
- Energy Usage: The maximum total energy use of the house, which includes heating, cooling, and electricity, cannot exceed 11.1 kwh per sq. ft. While there are no specific energy- use standards for code-built and energy star homes, estimates put their usage around 30 kwh and 20 kwh, respectively.
HERS rating: This score measures the energy efficiency of a house. A passive house is typically between 20 and 30 without the solar system. With a solar system, you can end up with a negative HERS score.
LEED: This is not worth pursuing. Very difficult and expensive. Lots of paperwork and not much benefit to us as homeowners.
Department of Energy Zero Energy Ready. These programs have some good concepts and we should work toward implementing them in our design. Many Habitat for Humanity homes are featured here as they work to providing efficient homes without the large price tag.
Living Future: A more comprensive view on what makes a home green.
Minnesota Green Path: Should be very simple and cost effective to achieve and would be a good idea to document, since we will do all these things anyway. It's not a very high standard to meet but it sounds good to a future buyer.
Energy Star Homes are not even close to an efficient house. This standard is so low that any house that doesn't meet it should not have been built.