Can you do a HERS Rating on an apartment in a 30-story building? Not now, but maybe in 2019!

ANSI/RESNET/ICC 301-2014 is the Standard for the Calculation and Labeling of the Energy Performance of Low-Rise Residential Buildings using an Energy Rating Index. It is the basis of the most common Energy Rating Index, RESNET’s HERS Index, which is utilized by utilities and building programs like LEED© and ENERGY STAR®, which require a consistent index to evaluate performance.

ANSI/RESNET/ICC 301-2014On March 2, 2018, RESNET released a draft of the 2019 version of ANSI/RESNET/ICC 301, where the most significant change will be the expansion of its scope to include Dwelling Units and Sleeping Units in ANY height building, whether that building is defined by IECC as “Residential” or “Commercial”. Other changes will include those developed by the RESNET Multifamily Sub-Committee, to better address shared systems like HVAC, hot water, solar PV, and laundry, and other scenarios specific to multifamily buildings that have largely been unaddressed until now.  The 1st preliminary draft standard of the 2019 version (dubbed PDS-01) includes these important improvements, along with all addenda to Standard ANSI/RESNET/ICC 301-2014 that were approved prior to March 2.

How does the revision process work?

The ANSI/RESNET/ICC Standards 301 (and 380) are under “continuous maintenance”. What does this mean? As revisions are needed to improve the standards, they are accomplished via “addenda”. Each addenda has to go through a “public comment” period to ensure that all stakeholders get to provide their opinions or objections to the proposed change before it becomes part of the standard. Rather than re-publishing a new edition of the standard each time a revision is approved, these standards are instead updated every 3 to 5 years to integrate any approved addenda into the body of the standard (instead of as separate addenda), along with any other necessary revisions into a new edition. This is similar to other standards like IECC, ASHRAE 62.2, or ASHRAE 90.1, which typically release a new version every 3 years. Read more

Multifamily Passive House Ventilation Design Part 2: HRV or ERV?

In climates with significant heating and/or cooling seasons, Passive House projects must have a balanced heat or energy recovery ventilation system. These systems use a heat exchanger to transfer heat and moisture between the outgoing return and incoming outdoor airstreams. The operation of recovery ventilators reduces the energy required to heat and cool decreasing the building’s carbon footprint. Project teams can select either:

  • Heat Recovery Ventilators (HRV) that transfer heat from the return air stream to the outside air stream; or,
  • Energy Recovery Ventilators (ERV) that transfer heat and moisture from the return air stream to the outside air stream.

Deciding between an HRV and an ERV gets more complex when the Passive House concept is scaled from a single-family home to a multifamily program. What the industry has learned from the development of airtight buildings and programs such as Passive House and R2000, is that indoor relative humidity must be controlled through continuous ventilation. The extremely air tight building envelope required of a Passive House, combined with high internal moisture gains from an occupant dense multifamily program (coming from occupants, kitchens and bathrooms), forces additional moisture management considerations during mechanical ventilation design. Maintaining acceptable interior relative humidity in both the heating and cooling season is paramount for building durability and occupant comfort. It’s appropriate that Passive House professionals claim this simple motto: “Build tight, ventilate right!”

In New York City where the multifamily Passive House market is rapidly growing, there is a significant heating season and a demanding cooling season with high humidity (Climate Zone 4A). With this seasonal variation, there are four primary operating scenarios for an HRV or ERV that need to be considered during design:

Summer Condition – HRV

An HRV operating in the summer (hot-humid exterior air and cool-dry interior air) introduces additional moisture to the building through ventilation. Heat is transferred from the incoming outside airstream to the return airstream leaving the building which cools supply air, but exterior moisture is not removed from the incoming air. The building’s dehumidification load increases as a consequence of additional moisture from the outdoor air.*CON*

HRV Summer operation Read more

The Energy Code of the Future: Modeling and Performance-Based?

It has been clear for some time that energy codes are on course to require carbon-free buildings by 2030. Adoption at the local level will see some areas of the country getting there even sooner. For example, California has set net zero goals for its residential code by 2020. These developments have accelerated the debate about the effectiveness of energy modeling versus performance-based approaches to compliance.

Chart: Improvement in ASHRAE Standard

Improvement in ASHRAE Standard 90/90.1 (1975-2013) with Projections to 2030. Courtesy of Pacific Northwest National Laboratory 2015

Let’s start with energy modeling, where change is coming for the better. In the past, the energy modeling community has been required to continuously respond to energy code cycle updates with new baseline models. That is, the bar for uncovering savings would be increased each and every time a new energy code was adopted. Following a code update, program staff and the energy modeling community would have to go through another learning curve to determine where to set a new bar and how to model the changes. Read more

Access+Ability: An Evening at the Cooper Hewitt Museum

Students used props to simulate sensory and mobility disabilities.

As part of Cooper Hewitt Lab | Access Design Teen Program and the museum’s ongoing ‘Access+Ability’ exhibition (on view through September 3, 2018), the Design for Aging Committee of the American Institute of Architects (AIA), New York Chapter, was invited to facilitate a workshop with high school students to explore challenges experienced by seniors and people with disabilities. As an Accessibility Consultant here at Steven Winter Associates, Inc. and a member of the committee, I had the opportunity to attend the event.

Students at the hands-on workshop were challenged to develop design solutions to address the needs of a hypothetical group of older adults attending a lecture on the 3rd floor of the Cooper Hewitt Museum. Included among the hypothetical attendees were people with visual, hearing, and motor disabilities and those with limited knowledge of the English language.

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Montgomery County Green Building Requirements


Montgomery County, Maryland recently passed new green building requirements, including adoption of the 2012 International Green Construction Code.  Montgomery County was one of the first jurisdictions in the country to enact a green building law in late 2007. Now, county officials have repealed the original law and replaced it with Executive Regulation 21-15 that will likely reduce requirements for many new buildings.

New Requirements

There are some pretty big changes brought about by the new law, which took effect on December 27, 2017 and includes a six month grace period for projects already under design. New projects permitted after June 27, 2018 will need to comply with the following:

  • Projects 5,000 gross square feet and larger must comply, lowered from 10,000 gsf.
  • Buildings must meet the 2012 International Green Construction Code (IgCC), replacing the requirement that buildings must meet LEED Certified criteria.
  • Residential projects under five stories must use ICC-700/NGBS at the Silver Energy Performance Level.
  • R-2 and R-4 portions of Mixed-Use buildings may comply with ICC-700/NGBS and the non-residential portion shall comply with the IgCC or the entire building may comply with IgCC or ASHRAE 189.1
  • R-1, non-residential and R-1/Mixed-Use projects may select IgCC, ASHRAE 189.1 or LEED Silver with eight points or more under the Whole Building Energy Simulation path.
  • All buildings using the IgCC compliance pathway must achieve a Zero Energy Performance Index (zEPI) score of 50 or lower.

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