PHIUS+ 2021 Source Energy Factor for Grid Electricity

PHIUS+ 2021 will include a change to the source energy calculation for grid electricity to more accurately reflect future grid conditions and better weigh the impact of electricity versus natural gas use on site.

In past versions of PHIUS+, the source energy factor for grid electricity was defined by the Energy Star Portfolio Manager and was determined based on past generation and consumption data from the EIA. The calculation methodology accounts for the total primary fuel needed to deliver heat and electricity to the site, including conversion losses at the plant as well as transmission and distribution losses incurred to deliver electricity to the building. Under PHIUS+ 2018, the source energy factor for grid electricity for the U.S. was 2.80, which was an average of the EIA reported data from 2012-2016.

With the release of  PHIUS+ 2021 the calculated factor for the United States grid electricity is 1.73 which reflects a 2050 outlook. 

Figure 1: U.S. power sector evolution over time for the NREL Mid-case scenario

Figure 1: U.S. power sector evolution over time for the NREL Mid-case scenario

Calculating a future source energy factor for the United States electric grid electricity required the combination of three data sets: 

(1) The projected future electricity generation mix, which was taken from NREL’s Mid-Case Scenario for 2050.

(2) Fuel conversion energy factors per generation type from the EIA.

(3) Total system losses from transmission, distribution and storage, taken from eGRID2018 and NREL’s future grid mix scenario.

A detailed description of the calculation methodology and corresponding data sources can be found in the PHIUS Tech Corner article. Read the full article here.


EPA Indoor airPLUS and Radon Resistant Construction

0Today’s guest blogger is Tony Lisanti, PHIUS+ QA/QC manager. 

One of the prerequisite programs required for PHIUS+ Certification is the EPA’s Indoor airPLUS Program.  Born out of a need to minimize indoor air pollutants, the EPA dove-tailed this program with the ENERGY STAR Labeled Homes Program, which is also a prerequisite for the home or dwelling unit to earn both Indoor airPLUS and PHIUS+.  This serves to ensure that the dwelling unit is relatively tight, insulation is properly installed, the HVAC systems are properly sized, and bulk moisture throughout the building assembly is properly controlled.

Indoor airPLUS then takes indoor air quality to the next level. Integrating the Construction Specifications and Checklist requirements into the design, homes/dwelling units can then be verified to ensure greater precautions are taken for moisture control and dehumidification, air intakes are protected from birds and rodents, HVAC systems are kept clean, better filter media is used, and potential sources of moisture and contaminants are vented to the outdoors. Additionally, HVAC systems and ducts are prohibited in garages, pollutants from combustion equipment are minimized, and low VOC products are used.

One of the unique and important aspects of Indoor airPLUS is the requirement for radon-resistant construction measures in EPA Radon Zone 1. If you are not familiar with the Radon Zone map, it can be found here:

Radon is a naturally occurring radioactive gas that can cause lung cancer. In fact, the EPA estimates that 21,000 deaths each year in the U.S. are attributable to radon exposure. The EPA has very good resources to read up on the health risks of radon. Their site can be found here:

So why should PHIUS stakeholders be concerned with this? As mentioned above, PHIUS relies heavily on prerequisite programs such as ENERGY STAR and Indoor airPLUS. Since the airtightness standards for PHIUS Certified projects are up to 10 times more stringent than a typical code-built home, dilution of the indoor air cannot occur as readily. PHIUS ventilation requirements go well beyond those of systems found in typical Code built or even Energy Star Labeled homes. Good ventilation design, whether for code or for PHIUS starts with source control, i.e. minimizing the source of contaminants along with proper ventilation.

An example of a passive radon system.

An example of a passive radon system.

In high risk areas such as Radon Zone 1, EPA Indoor airPLUS requires installation of a passive radon system, at minimum. EPA also recommends utilizing active radon systems to further reduce radon concentrations in the home, although this is not yet an Indoor airPLUS requirement. The most modern radon standards are developed through an ANSI-accredited consensus process by the AARST Consortium (American Association of Radon Scientists and Technologists). EPA recommends following the ANSI/AARST CCAH Standard for 1-2 family dwellings and townhouses (max. total foundation area of 2500 sq. ft.) or the ANSI/AARST CC-1000 Standard for larger foundations, which often apply in multifamily buildings. However, the key components of a passive radon system for the purposes of Indoor airPLUS verification are succinctly outlined in Item 2.1 of their Construction Specifications.

ANSI/AARST will soon publish updated standards to provide guidance for the design and installation of two radon system options in new low-rise residential buildings. These systems, passive and powered, are designed to reduce elevated indoor radon levels by inducing a negative pressure in the soil below the building. The practice provides design and installation methods through soil depressurization systems that can be installed in in any geographic area.

Each of the two options consists of soil gas collection and a pipe distribution system to exhaust these gases. The first standard is for the design of passive radon reduction systems, sometimes referred to as a “radon rough-in” (ANSI/AARST RRNC). The second newly updated standard (anticipated in early 2020) includes details for a fan-powered radon reduction system, as well as radon testing (ANSI/AARST CCAH). Passive systems can result in reduced radon levels of up to 50%. These standards suggest that when radon test results for a building with a passive system are not acceptable, the system be converted to fan-powered operation. Typically, the action level is 4 pCi/L (Picocuries per liter). If the tested radon level exceeds 4pCI/L, then a fan is added to further depressurize the soil and positively vent the gas to the outside.

Recently, the EPA Indoor airPLUS team sent out this Technical Bulletin. The Technical Bulletin provides simple guidance on the installation of passive and active radon systems. Please pay particular attention to the drawings in the Bulletin, and note that the active system depicted has the fan located in a vented attic. This is outside the pressure/thermal boundary of the home. This has special significance with homes/buildings constructed to PHIUS Standards, because often, the attic space is WITHIN the pressure/thermal boundary of the home. Therefore, the fan cannot be located in the attic and must be outside the pressure/thermal boundary. The reason for this is, should there be a failure on the discharge or pressurized side of the fan, the building can actually be filled with radon gas.

Some other precautions that include a tight seal at the slab and vapor barrier to the vertical riser. Additionally, ensuring the riser is clearly labeled as “RADON” to minimize the chance that a plumbing waste line will be accidentally connected to it in the future is also important.

Tony Lisanti CEM, CPHC
PHIUS+ QA/QC Manager

With thanks to Nicholas Hurst from the EPA Indoor airPLUS Team

Policy Update: New York State—Two Steps forward, One Step back

isaac picIsaac Elnecave, a member of the PHIUS certification team, has written this update on the New York State stretch cove.

Over the last year, the state of New York has made significant progress towards making the PHIUS+ standard an integral part of its energy code. It points the way to the end goal of creating a cost-effective net-zero energy code.

Besides its statewide base code, the New York State Energy Research and Development Authority (NYSERDA) promulgates a “stretch” energy code (NYStretch-2020). The base energy code governs the energy requirements in buildings throughout the state. The requirements include such items as: the amount of insulation required in ceilings, walls and foundations, window performance, the level of air tightness, ventilation requirements, the efficacy of lighting and the efficiency of HVAC equipment. It is often described as the worst possible home that can legally be built.

A stretch energy code incorporates energy efficiency requirements that are more stringent than the base code (NYStretch-2020 is roughly 11% more energy efficient than the base code). While the base energy code is the default requirement across jurisdictions in the state, the stretch energy code must be affirmatively adopted by local municipalities (authorities having jurisdiction) that want to enforce it—at which point, it overrides the state code in that jurisdiction).

Besides providing energy savings beyond the base energy code, NYStretch-2020 was developed with the following goals in mind:

• Technically sound
• Thoroughly reviewed by stakeholders
• Written in code enforceable language
• Fully consistent with the 2018 IECC, ASHRAE 90.1-2016, and uniform codes

Moreover, NYSERDA strongly encourages, but does not require, that a jurisdiction adopting the NYStretch-2020 do so without making amendments.

In NYStretch-2020, there is a section for alternative compliance strategies (R-408), which specifically names passive house; a single-family home or low-rise multi-family certified under PHIUS+ would automatically meet code. The stretch code specifies that the specific space heat demand and (sensible only) cooling demand, as modeled and field-verified by a CPHC (Certified Passive House Consultant), must be less than or equal to 9 kBTU/ft2/year. A dwelling unit shall also be tested with a blower door and found to exhibit no more than 0.05 CFM50/ft² or 0.08 CFM75/ft² of air leakage. Ultimately, to provide a Certificate of Occupancy, a code official must submit a form that must indicate that the finished building achieves a CPHC verified specific space heat demand of less than or equal to 9 kBTU/ft2/year.

It is important to note that the PHIUS standard is even more energy efficient than the requirements in NYStretch-2020. Here is a link to NYStretch-2020: file:///C:/Users/phius/Downloads/NYStretch-Energy-Code-2020%20(7).pdf.

New York City
New York City provides an example of the importance of the stretch energy code. Local law 32 requires the city council to adopt the New York State Stretch code (allowing the inclusion of amendments). The language of the law is fairly clear:

Submit to the city council proposed amendments to this code to bring this code up to date with the most recent model stretch code published by the New York State Energy Research and Development Authority, provided that such model stretch code is more stringent than the New York State Energy Code in effect when such proposed amendments are submitted and provided further that such model stretch code was first published no more than three years before such proposed amendments are submitted;

As noted in the previous section, NYStretch-2020 is significantly more energy efficient than the base state code. Consequently, the city council is about to adopt NYStretch-2020 with one very important and unfortunate exception. R408, the section of NYStretch-2020 which allows for an alternate compliance path using PHIUS+, has been deleted. Here is a link to the proposed energy code  (Click on Int. No. 816 for the text of the code).

It is unclear as to why section R408 was deleted but it removes an important alternate compliance option for designers and builders. PHIUS+ incorporates both rigorous design standards with robust quality control protocols to ensure that the building is both energy efficient and well-constructed.

As the PHIUS standard is more energy efficient than the provisions of the NYStretch-2020, it also provides a target for future code improvements while giving designers and builders the time to develop expertise in building energy efficient dwellings; ultimately leading to the establishment of a net-zero energy code.

A Climate Action Turning Point!

That's friend of PHIUS and visionary NYC architect Chris Benedict (l) with Katrin Klingenberg.

That’s friend of PHIUS and visionary NYC architect Chris Benedict (l) with Katrin Klingenberg.

On October 29th I was fortunate to attend the NYSERDA low carbon and zero energy Buildings of Excellence Awards at the Building Energy Exchange in New York City. What a terrific time for projects that are about to and that have employed PHIUS+ passive building standards as baseline to get to zero energy ready! I counted at least 10 PHIUS+ project teams in NYSERDA’s three categories, Early Design Stage, Substantial Completion and Completed, that were awarded up to 1 million dollars for their projects!The awards were announced on the 7th anniversary of super storm Sandy, not a coincidence, as a reminder for urgent climate action. Seven years later, NYC is leading by action and is putting itself firmly on the path of global leadership in building energy and resilience. Thank you to an amazingly dedicated NYSERDA team for making this happen!

The week before the event, I keynoted the Boston Passive House Massachusetts Symposium to talk about the evolution of the PHIUS+ certification suite for passive buildings, and why they provide such great value on the path to ZERO. Here as well, political action was taken to combat climate change: MassSave staff announced significant incentives for low carbon and zero energy buildings and significant additional incentives if project teams go for passive building certification for their hi-rise residential projects. Certification requests from Mass have increased manifold as a result. Massachusetts in not far behind NY State in political will, turns out.

And just a few weeks before the Boston event, it was gratifying to find that at the Getting to Zero Forum in Oakland, California, passive building was simply understood as the logical starting point on the path to ZERO, no questions asked. During one of the plenaries the ASHRAE speaker proudly introduced the new ASHRAE standards committee: 227p Passive Building Design Standard. That was great news and evidence that ASHRAE is moving on the topic.

During the lunch plenary on day one the National Renewable Energy Laboratory featured PHIUS board member Mary Rogero’s students presenting their Solar Decathlon winning PHIUS+ Source Zero energy school design. For the closing plenary, California’s Commissioner Andrew McAllister presented on his recently completed and only recently occupied zero energy passive house in Berkeley and the benefit of energy independence. He had electricity while PG&E had shut off power supply to prevent fires, a consequence of climate change, to most of Berkeley including the entire Berkeley Campus. He was followed by Greg Hale, from NYSERDA, who spoke about applying the Energiesprong passive plus zero energy retrofit approach that he is spearheading in NYS and other zero carbon measures taken by the city.

And while most of the building action seems to be happening on the East Coast, quietly behind the scenes advocates have been working hard to get passive building into codes all over the country. When PHIUS was first established our lofty mission was to make passive building code by 2020. As ambitious a goal that was then in 2007, we have made significant progress toward it, and have paved the path for national success. NY State has included passive building as an alternative compliance path into the next stretch code and Washington State is on a similar path. Massachusetts has included an alternative compliance path for passive buildings and verification tools (no double modeling required) and Washington, D.C. also has included an alternate compliance path for passive buildings in their about to be launched ZERO Energy Code.

Most significant of all those developments is the establishment of the ASHRAE 227p standards committee. If successful they’ll created a passive building design standard that takes the best pathways from all existing programs and develop an even better, easily adopted design standard globally. That committee has now started its so very important work. The ball is rolling! Stay tuned for more!

Exciting times, indeed!





WUFI® Passive V. validation using ANSI/ASHRAE Standard 140-2017

Good news: PHIUS has completed modeling to validate WUFI Passive according to ASHRAE 140. Read the full report here

ASHRAE 140 is a comprehensive Standard Method of Test (SMOT) for the evaluation of building energy analysis computer programs. The ASHRAE 140 report provides the information accrediting agencies or jurisdictions need for validation or acceptance of WUFI ® Passive for code and policy purposes. In short, the standard describes test buildings (cases) in significant detail in order to model the building and compare results versus other software. It contains a comprehensive description of test procedures, as well as predictions generated by WUFI Passive software evaluated against predictive benchmarks.

The table below provides a description of the test cases used for ASHRAE 140 Validation. 

Table 1

Annual Heating and Annual Cooling Load results were reported for most cases, except for L302-L324A which only analyzed heating. WUFI Passive results fell well into the suggested acceptance ranges in all test cases when following Class II Procedures of ASHRAE Standard 140.  Most results fell toward the center of the confidence range as shown in the graphs below.
AHL Results

ACL Results

Authors: Lisa White, Jasmine Garland