July 16, 2019|

Net Zero and Passive House – The Future of Home Building

  • Understanding Zero Energy Ready Homes with Sam Rashkin | via ECHOtape

For homebuilding in the U.S., the future is now. The U.S. Department of Energy (DOE) has established a goal that all new buildings in the U.S. will be built to a net-zero-energy standard by 2030. With only a decade to go, the good news is that zero energy ready homes in the U.S. and Canada increased by 100%!  That said, there’s still more work to be done. Here’s what you need to know.


What Does Net Zero Mean?

Net Zero means producing as much energy as one consumes over the course of a year. Typically, buildings are designed to minimize the amount of energy used by incorporating well insulated and controlled enclosures, energy-efficient products, and sustainable infrastructures. On-site energy generation through solar or wind is used to offset consumption.

To aid builders in making the leap to a net-zero project, the DOE created the Zero Energy Ready Home program or ZERH. Designed to be the next step up after meeting ENERGY STAR(r) requirements, and launched in 2012, by 2017 the program had 2,000 homes certified. With 10,000 homes in the pipeline for certification after 2017, the exponential growth reveals increased builder interest in meeting consumer demand for energy-efficient, resilient, quality-verified homes.

According to Samuel Rashkin, Chief Architect of the Building Technologies Office in the Office of Energy Efficiency and Renewable Energy, “Any meaningful reduction in CO2 emissions requires a transformative change to how we use energy in buildings because they consume over 40% of all electric power generation and nearly 75% of electricity (EIA 2012). Furthermore, residential buildings represent more than half of the energy consumption in buildings (EIA 2012). Zero energy ready buildings are imperative for any strategy designed to manage planetary risk.”


Making Sense of Zero Energy Ready Homes 

The program builds upon the comprehensive building science requirements of ENERGY STAR® for Homes Version 3, along with proven Building America innovations and best practices. Other special attribute programs are incorporated to help builders reach unparalleled levels of performance with homes designed to last hundreds of years.

DOE Zero Energy Ready Homes are verified by a qualified third-party and are at least 40%-50% more energy-efficient than a typical new home. This generally corresponds to a Home Energy Rating System (HERS) Index Score in the low- to mid-50s, depending on the size of the home and region in which it is built.

DOE Zero Energy Ready Homes must meet all DOE Zero Energy Ready Home National Program Requirements (Rev. 07) for homes permitted on or after June 1, 2019.

In brief, DOE Zero Energy Ready Homes must:

    • Thermal enclosure
    • HVAC quality installation (contractor and HERS rater)
    • Water management
    • The target home/size adjustment factor used by ENERGY STAR
  • Feature energy-efficient appliances and fixtures that are ENERGY STAR qualified.
  • Use high-performance windows that meet ENERGY STAR v5.0 and v6.0 specifications (depending on climate zone). The required U and solar heat gain coefficient (SHGC) values are shown below, effective 8/22/2016.

Builders can follow two different paths in qualifying homes for the DOE Zero Energy Ready Home initiative.

  • Prescriptive Path. To use the prescriptive path, follow the DOE Zero Energy Ready Home National Program Requirements. A registered verifier should submit the prescriptive compliance report after verification that the home meets the challenge.
  • Performance Path. Registered verifiers can use RESNET-accredited software programs to qualify homes to meet the DOE Zero Energy Ready Home requirements. The software will create a DOE certificate specific to the certified home.

Understanding Passive House Standards in the U.S.

Long known in Europe, Passive House offers a second approach to minimizing or eliminating home energy consumption. The regulations and standards of Passive House construction are based on insulation values, the use of sunlight, and an airtight infrastructure in order to maintain a steady temperature within a home throughout the year.

Passive building comprises a set of design principles used to attain a quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level. “Optimize your gains and losses” based on climate summarizes the approach. To that end, a passive building is designed and built in accordance with these five building-science principles:

  • Employs continuous insulation throughout its entire envelope without any thermal bridging.
  • The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air.
  • Employs high-performance windows (double or triple-paned windows depending on climate and building type) and doors – solar gain is managed to exploit the sun’s energy for heating purposes in the heating season and to minimize overheating during the cooling season.
  • Uses some form of balanced heat- and moisture-recovery ventilation.
  • Uses a minimal space conditioning system.

Practically speaking, these guidelines create incredibly comfortable homes, lacking the drafty, cold spots that poor insulation and inefficient windows can create. Another advantage of Passive homes is the lack of maintenance involved when compared to other environmentally friendly options; when properly sealed, insulation and glazed windows will last for decades with virtually no maintenance required.

The first U.S. passive home was constructed in Urbana, Illinois around 15 years ago. PHIUS+ Certified and Pre-Certified projects now total more than 2.5 million square feet across 2,300 units nationwide! The cost-optimized PHIUS+ 2015 Standard is spurring new growth in passive buildings from coast to coast, with the most significant gains coming from the multifamily housing sector.


Why Do We Care?

Why does this matter? Well, in the US, buildings account for a whopping 70% of our electricity consumption and roughly 40% of carbon emissions – that’s more than either the transportation or industry sectors!  Clearly, we need a revolution in the way we build and renovate our homes and offices, and ECHOtape is heavily invested in being part of the solution. Our flexible products can help builders and contractors achieve Net Zero via air sealing and insulation efforts noted in Steps 3, 4, 5 and 6 in the article, Twelve Steps to Affordable Zero Energy Home Construction.

Here’s the good news:  The Net Zero Energy Coalition reports that zero energy ready residential buildings in the U.S. and Canada increased by 100% between 2015 and 2017.  Indeed, the U.S. alone had a 75% increase in zero net energy home construction between 2016 and 2017. And according to Dodge Data & Analytics, 44% of surveyed builders planned to have a net zero or near zero home built by 2019.

For builders and contractors, the DOE has a Zero Energy Ready Certification Program for zero energy ready homes. These homes must meet rigorous requirements that ensure energy efficiency, comfort, health and durability. Earth Advantage has a Zero Energy Ready Certification program for homes in Oregon and Washington, and Passive House has the most rigorous certification program with energy efficiency standards that exceed the DOE’s standards. Homes which qualify for Passive House Certification simultaneously qualify for DOE Zero Ready Certification. The Canadian Home Builders Association also offers a Net Zero Energy Labelling Program.

If you’re curious to learn more about Net Zero Home Building Techniques, check out this great YouTube channel.

 

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