Party Walls

This October, Governor Cuomo announced with former Vice President Gore that New York will join the Under 2 MOU effort to join states and cities around the world in pledging to reduce GHG emissions 80% by 2050. The Under 2 MOU is a global joint effort to encourage action at the Conference of the Parties meeting at the 21st UN Conference on Climate Change in Paris later this year.

This is not the first commitment that impacts performance targets for buildings in New York. Both the city and state have committed to deep reductions in emissions that have regulatory and programmatic impacts on buildings.

What Targets are in Place?

The Under 2 MOU program is already in line with New York’s same self imposed target in place: 80 by 50 via Executive Order No. 24 which was signed in 2009. New York is one of 20 states, plus DC, with a target in place.

New York City has a comparable target.  In September 2014 the One City Built to Last plan also targeted an 80% reduction by 2050. But to reach this target, the city needs to reduce 30% of GHG from the building stock by 2025.

How Does New York Reach These Goals?
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If nothing else, people are adaptable. While something might be an annoyance at first, we often figure out a way to manage it and move on. Unfortunately, we all too often do this when it comes to our greatest life investment…our homes. Whether an existing or new home, we almost always are not comfortable in our home or at least portions of our home. One, several, or even the entire home may never be at desirable conditions, but we learn to cope with it by putting on layers of clothing or adding small electric heaters to cold spaces, or supplemental fans in hot ones. So we are not comfortable as we allow our conditioned air to easily escape our homes and our utility bills continue to be high. The simple question is…why?

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SWA’s Senior Mechanical Engineer, Lois Arena, P.E., is one of the leading Passive House (PH) specialists in the country. She is regularly asked to speak about PH at conferences, after-hour educational events, and to firms seeking to increase their knowledge about the subject. For SWA’s clients, she provides a full suite of PH services including energy modeling and consulting to optimize energy efficiency and ensure that projects are designed and built to meet the rigorous Passive House Standard, as well as field testing throughout the construction process to aid the team in achieving the strict PH air leakage requirements.

In addition to working on multiple projects in the tri-state area, she is currently contributing to the groundbreaking Passive House project for Cornell’s new technical campus on Roosevelt Island. When completed, the residential tower will the tallest and largest Passive House building in the world!

The project has earned a lot of media coverage, from a groundbreaking ceremony that was attended by both NYC’s current Mayor Bill de Blasio and former Mayor Michael Bloomberg to an article in the New York Times and other media outlets. And of course now, on our Party Walls blog, where I was able to get the inside scoop on the project straight from the source!

Was Passive House certification Cornell’s initial goal for this project or was it recommended based on efficiency goals set by the owner or developers? (more…)

With the adoption of the innovative Green Construction Code in 2013, there has been quite the learning curve for those looking to build in Washington DC. Green construction codes are a relatively new concept within the building industry. Many jurisdictions, builders, architects, developers, and contractors, have minimal experience in applying them. To support building developers and the general public in successfully designing and building  to the new green and energy code requirements, regulatory bodies such as the Department of Consumer and Regulatory Affairs (DCRA) and the District Department of the Environment (DDOE) have worked to create tools, trainings, and educational resources.

Interactive Green Building Displays 

Your next visit to the DCRA or DDOE will be unexpectedly educational, when you discover the recently added green building displays developed by SWA. With hopes of providing accessible, consumer facing green building education, the displays cover energy efficient building techniques and strategies that can be used to meet the energy and green building requirements adopted by the District Government. The displays are both visually appealing and interactive and provide examples of green building features, code best practices, as well as provoke interest in green building and sustainability for District employees, building professionals, and the general public.

DC Green Building Roadmap Tool  (more…)

Step 1: Understand the LEED for Homes process

The U.S. Green Building Council developed the LEED® (Leadership in Energy and Environmental Design) for Homes™ and Multifamily Midrise™ Rating Systems to assess and validate residential green building practices.

The LEED for Homes and LEED for Homes Midrise certification process is outlined in this video provided by USGBC.

In addition to meeting the rating system requirements, every LEED Homes and Midrise project is inspected and tested during site inspections by credentialed LEED Homes Green Raters. Steven Winter maintains a team of 11 credentialed Green Raters serving 20 states including New York, Connecticut, Virginia, Maryland, Pennsylvania, New Jersey. Massachusetts, and more.

How Does LEED Homes Compare to Other LEED Rating Systems? (more…)

As the latest versions (2012 and 2015) of the International Energy Conservation Codes (IECC) push for more efficient homes, we are getting more questions from architects on how to achieve the air tightness requirements of 3 ACH50. There is no one correct answer, but it can be often achieved through taping of exterior structural or insulated sheathing, air sealing of wall cavities prior to insulating, and/or the use of insulation that is restrictive of air movement. The most common approach that we are asked about is the use of open cell spray polyurethane foam (ocSPF), as it is air impermeable (required thickness is dependent on the specific product, so check requirements in the ICC Evaluation Services Report), reasonably priced, and theoretically, doesn’t require any changes to standard builder practices. While it is true that ocSPF will provide air sealing cost-effectively, we typically do not recommend it in our cold climate region without additional measures due to risk potential over time. To effectively build a home with ocSPF, thoughtful detailing and a high level of execution is required to ensure that it remains effective 5, 10, 15…25 years from now.

• ocSPF is vapor permeable, so there is a greater potential for condensation in the building enclosure than if closed cell spray polyurethane foam (ccSPF) is used. A hybrid approach of ccSPF and an alterative insulation (ocSPF, cellulose, fiberglass, etc.) is often used to keep costs down.
• ocSPF can absorb 40% of water by volume. Therefore, if bulk water from leaks does make it into the building enclosure, the ocSPF will retain the water until saturated. Pinpointing the source of the leak may be difficult as the water can migrate within the foam.

Our main concern is that the performance of the product requires several trades to meet a high level of quality to ensure success and hope that the homeowners don’t unwittingly cause problems down the road through lack of maintenance. Here’s what we suggest…  (more…)

There were 11 projects entered into this year’s CT Zero Energy Challenge, sponsored by EnergizeCT.  The single- and multi-family homes taking part in this competition are designed and constructed utilizing innovative techniques in order to try and reach the illustrious goal of net-zero energy-use.

I’m excited to report that SWA worked with 4 of the homes entered into this year’s competition, including the first- and third-place winners! For each of the three winning projects, EnergizeCT has created a video to showcase the story behind the homes, and to highlight some of the most notable features.

Today’s video is about the first-place winner, a single-family home in South Glastonbury, CT, constructed by Glastonbury Housesmith. The owners, Carl Benker and Elizabeth Wegner are first-time homebuyers who wanted to be able to live as close to “off the grid” as possible. Check out SWA’s HERS-rater extraordinaire, Karla Donnelly, discussing the competition, and how this home came to achieve an amazing HERS Index Rating of a -23!

(Right-click and select “run this plug-in” if you cannot see the video below)

 

The project also won the 2015 RESNET Cross Border Challenge for lowest HERS score with photovoltaics (PV)!

You can read more information on SWA’s project here. 

Ten years ago, seeing a solar electric system on a building was noteworthy. Now they’re popping up everywhere. Lower cost is obviously a big driver of this solar surge; photovoltaic (or PV) system costs have dropped 50-70% in the past 10-15 years. Over the past decade, SWA has helped developers and owners install PV systems on hundreds of buildings. The systems are reliable, they have no moving parts, and they will convert sunlight to electricity for decades.

The cost effectiveness of PV, however, is not always clear. In fact, SWA has seen a concerning trend where the cost benefits of PV are exaggerated. Although costs vary with region and application, installed costs of PV are usually $3,000 – $6,000 per kWSTC.

Then there are incentives, including two key federal programs:

• 30% Federal tax credit
• Accelerated depreciation (for businesses)

Other incentives vary greatly from region to region:

• State, local, and utility rebates or credits
• Sale of Renewable Energy Credits (RECs)

The Database for State Incentives for Renewable Energy (dsireusa.org) has a good summary of these regional incentives. Federal and regional incentives can easily lower PV system costs by 50% — often more.

The final piece in assessing cost effectiveness of PV is the electricity savings. With PV generating electricity for your building, you’ll obviously be paying less to the utility. But how much less? (more…)

Fannie Mae recently reinforced their commitment to growing the green multifamily sector with the announcement of a reduction in interest rates for mortgage loans used to finance properties certified through a recognized green building rating system. There’s detailed information available on their website, but here’s a simple breakdown of the initiative using the 5 W’s:

Who: Fannie Mae Multifamily borrowers, developers, designers, and occupants

What: 10 basis point reduction in mortgage loans for multifamily properties certified through a recognized green building rating system (LEED, ENERGY STAR®, Enterprise Green Communities, etc.)

Where: Multifamily projects nationwide

When: Immediate implementation. Through existing green initiatives, Fannie Mae has already financed $130 million in Green Loans to properties with a Green Building certification

Why: Strengthens market for high-performance building design; Reduces financial risk for property owners; Raises property value with high performance upgrades

Visit the overview page for detailed information on Fannie Mae’s entire portfolio of Green Initiatives

BACKGROUND

The multifamily building industry has adopted a best practice long touted by the building science community: continuous insulation at the exterior of the building. However, even in this ideal circumstance in which the insulation is installed flush and without gaps against the exterior substrate (concrete block or sheathing) with an air barrier applied to this substrate beforehand, the overall performance of the insulation will be vastly reduced by the installation of shelf angles.

Shelf angles (also know as relieving angles) are designed to support the expansion and contraction of the brick coursing; however, this presents a direct challenge to the continuity of exterior insulation. Standard design details interrupt the exterior insulation at every shelf angle, typically at every floor in line with window lintels. Since the shelf angle is made of steel, a highly conductive material, this interruption impacts not only the effectiveness of the insulation in general, it provides a considerable thermal bridge over the entire horizontal band of the building at every occurrence.

A recent article by Urban Green Council, “State Energy Code Clarification Will Stem Heat Loss through Walls,” made it clear that a continuous shelf angle has “about the same poor thermal performance as [an] exposed slab edge.” The full article can be read here.

 

SWA RECOMMENDATION #1: LIMITING SHELF ANGLES

Not all buildings require relieving angles. Building owners, architects, and structural engineers should first ask themselves whether relieving angles are necessary at all for the building being designed. If it is determined that these angles will be necessary, the next question the structural engineer should ask himself is what the minimum frequency necessary is to support the brick course. Generally speaking, buildings do not need one shelf angle per floor—despite this being common practice.

In addition to the aforementioned energy implications involved in specifying shelf angles, there are other benefits to eliminating these steel members when possible. The most obvious impact is on upfront costs. At approximately $25/foot of angle iron (via Union Iron Works), shelf angles for multifamily buildings in New York City can cost tens of thousands of dollars.

Upfront and operating (i.e. energy) costs aside, there is also the embodied energy of the material to consider. Not only does the manufacture of the steel angle contribute to its embodied energy, but also all of the energy used to transport these pieces to the project site. By reducing the need for the production of these angles, the overall energy expended to construct a new building decreases.

One additional consideration for owners is the maintenance required for shelf angles. The introduction of brick lintels creates an inherent and inevitable need for future maintenance. Since the cost of this upkeep is often considerable, owners may wish to use the opportunity to limit shelf angles during design to reduce long-term maintenance costs.

 

SWA RECOMMENDATION #2: OFFSETTING SHELF ANGLES

In addition to limiting their frequency, consider a shelf angle offset to further reduce thermal bridging. One such system that allows for this is manufactured by FERO called FAST (FERO Angle Support Technology).

FAST is designed to offset the shelf angle from the structural backing, allowing the insulation and air barrier installations to be more continuous. More information about this product can be found on their website.

SWA welcomes the input of design teams for other possible solutions to achieve a more continuously insulated wall. By accomplishing this, the building will have a truly continuous thermal envelope. As a result, thermal bridging will be eliminated along with the associated energy losses.

 

 

CONCLUSION

To implement best building practices, fulfill the continuous insulation requirements of certification programs, and comply with NYC Energy Conservation and Construction Code, SWA recommends limiting the number of shelf angles in the construction of the envelope. This will help limit upfront material and long-term maintenance costs.

SWA also recommends off-setting the shelf angle to reduce the thermal bridging these steel elements create. Fewer shelf angles means that there are less obstacles imposed on exterior insulation, resulting in less thermal bridging. Limiting the impact of shelf angles produces a more robust and insulated envelope that will, in turn, positively impact the energy performance of the building and comfort of its occupants.

SWA would like to thank Robert Murray for his assistance with this article.

Robert J. Murray, P.E., LEED AP, Principal
Murray Engineering, PC
307 Seventh Avenue, Suite 1001
New York, NY 10001
Telephone: 212.741.1102
Email: rmurray@murray-engineering.com

 

REFERENCES

1. Anderson, J., D’Aloisio, J. DeLong, D., Miller-Johnson, R., Oberdorf, K., Ranieri, R., Stine, T., and Weisenberger, G. “Thermal Bridging Solutions: Minimizing Structural Steel’s Impact on Building Envelope Energy Transfer.” American Institute of Steel Construction. Modern Steel Construction, 1 Mar. 2012. Web. <http://msc.aisc.org/globalassets/modern-steel/archives/2012/03/2012v03_thermal_bridging.pdf>.

2. FERO: Engineered Construction Technologies. Product Catalogue. Edmonton: FERO: Engineered Construction Technologies, 2014. Web. <http://www.ferocorp.com/pages/fast/fast.html>