A Tour of DURA, New York City College of Technology’s Urban and Resilient Solar Decathlon Home

Last week, I had the opportunity to visit the DURAhome, New York City College of Technology’s entry for the 2015 Solar Decathlon. This project is currently nearing completion at the Brooklyn Navy Yard. Over the past 3 months, more than sixty students have toiled around the clock to finish construction in time for the contest, which will take place October 8-18 in Irvine, California. The Solar Decathlon is the U.S. Department of Energy’s biennial competition that challenges college and university student-led teams to design and build solar-powered net-zero homes that are affordable, energy-efficient, and aesthetically appealing.

TeamDURA’s focus was to create a prototype of post-disaster housing that is suited for New York City’s high-density urban environment, and could serve as a shelter in the aftermath of a catastrophic storm. As such, multifamily, multistory solutions were preferable to traditional single-family trailers, which have larger footprints. DURAhome consists of several prefabricated modules that can be packaged and shipped on standard-sized tractor trailers for quick response at low cost. These flexible modules can then be joined in standalone configurations or stacked for multifamily uses. Like the city, the DURAhome is diverse, urban, resilient, and adaptable.

NY City Tech Freshman Langston Clark continues work on DURA into the early evening.

NY City Tech Freshman Langston Clark continues work on DURA into the early evening.

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Community Microgrid: Resiliency via Energy Independence

SWA Senior Mechanical Engineer Lois Arena discusses the recently announced community microgrid project based in the Village of Mamaroneck. The Westchester County village is among 83 New York communities to be awarded $100,000 by the New York State Energy Research and Development Authority (NYSERDA) to conduct a microgrid feasibility study.

Steven Winter Associates and Murphy Brothers Contracting, along with a team of technical experts and local leaders, will assess the challenges, benefits, and costs associated with using microgrids to improve resiliency and recovery time during a significant power outage, as well as to offset peak demand energy use.

This segment is part of LMCTV‘s videocast of the Murphy Brothers Contracting “10 Steps to Ensuring Those Beautiful Custom Homes are also Comfortable, Long Lasting, and Efficient” event. Watch LMCTV’s complete coverage of the event here.

 

Get This: Engineer Runs House with Car!

Gayathri Vijayakumar, a seasoned Buildings Systems Engineer at SWA ,took a unique precaution against future electrical power outages…

Gayathri connected her Toyota Prius to her New Haven home’s power system.

Gayathri and her Prius

How did she do that?

Gayathri took a special inverter and connected it to her hybrid car, which created a generator. This distinctive system works by connecting the inverter to a transfer switch and starting the Prius, generating enough electricity (1600 Watts) to run the critical circuits in her house, including pre-selected lights, refrigerator, and the electric ignition to the tankless gas water heater.

The inverter, purchased from ConVerdant Vehicles, was less expensive than a standard gas generator, provides electricity by using half the fuel, and is much quieter.

Inverter

 “We were not prepared for our first power outage in Connecticut, but we were able to use the gas stove for cooking and our gas fireplace kept the first floor at well over 70F. Being without a fridge and hot water was a challenge though. Now that we have the Prius, at $4/gallon of gas, generating electricity through the inverter is still more than twice as expensive as buying it from the utility. But in a power outage situation, being able to provide basic power for three days on one tank of gas is pretty amazing” said Gayathri.

Mother Nature is showing us that even though it is critical to focus on energy-efficient building designs and renewable systems, we must include storm resiliency as another component of designing truly sustainable buildings.

Have you taken any unique precautions to protect your home/building against future storms?

Stop Those Air Leaks – All About Infiltration

What is Infiltration?

Infiltration is the uncontrolled or accidental introduction of air, often called air leakage.

A lot of people assume air leaks happen predominately around windows and doors. In actuality air is driven through our homes and buildings by the stack effect – warm air rising. This means the attic or the roof, and the basement, are most critical for preventing air leaks and infiltration. Infiltration is a bad thing: not only is it a huge energy waste, it brings in air from the dirtiest places like attics and crawlspaces, and spreads that contaminated air through the living space.

The key to stopping infiltration is creating a good air barrier.

Think of a building’s insulation like a wool sweater. On a calm fall day the sweater is enough to keep you warm. If a breeze picks up, though, the cold wind will blow right through the wool and you will probably reach for your windbreaker. In a home we call the windbreaker layer the air barrier, and it is just as important as the insulation. Insulation limits heat transfer through the walls and roof, but only when paired with an effective air barrier.

Stop Infiltration – Air Barrier Rules

  1. air sealing detailsThe air barrier needs to be totally continuous. If you take a cross-section plan of the building, you should be able to draw the air barrier all the way around without lifting your pen.
  2. The air barriers, such as drywall, should be in direct contact with the insulation. This often breaks down in locations like walls under staircases, behind fireplaces, and under tubs where there is (hopefully) insulation but no drywall air barrier.

Where Does Most Infiltration Occur?

There are three critical types of air leaks to watch out for:

  1. Big holes.  Some common design elements can result in big holes in the air barrier. For instance, a dropped soffit is a great pathway for air leakage. Tubs and fireplaces on exterior walls can create similar holes if a solid piece of rigid insulation isn’t installed behind them. Floor joists that extend from conditioned space to a garage or balcony are another way to blow open the air barrier. While these locations can be air-sealed and insulated, good design would eliminate the potential for big holes altogether.
  2. Cracks.  Every building has a number of cracks that seem minor when taken on their own, but add up to a big air leak. These cracks occur between the sill plate and foundation, at exterior wall bottom plates, between adjacent studs, and around window and door frames.
  3. infiltration at can lightPenetrations.  Every hole cut in the exterior envelope (ceiling drywall, exterior sheathing, top plates below attic) creates a potential air leak. Penetrations include plumbing pipes, duct registers, can lights, exhaust fans and exhaust ducts, and electrical wiring.

Air is relentless: it will find any and every pathway into a building. Sealing 50% of the apparent leaks will not cut 50% of the infiltration because air will find another way in. Good air sealing aims to seal 90% of the leaks. It requires patience, attention to detail and the expertise to recognize tricky air bypasses. It also requires a clear understanding of the thermal envelope, especially at complicated architectural details.

Tips for Successful Air Sealing:

  • Good air sealing requires a plan, and should be a priority during the design phase. Ask yourself where is the air barrier? Can you draw it without lifting your pen? Check out our tips for multifamily compartmentalization.
  • During construction, air sealing should be the responsibility of all the trades. Air is persistent, and the whole project team needs to be just as thorough in fighting it.
  • A good rule for a job site is if you cut a hole, you seal it. It is easier for each trade to seal their own holes, rather than relying on one person to find everyone else’s holes.
  • Fire-stopping is not necessarily air sealing. Fire-stopping material like rock wool does virtually nothing to stop air infiltration. Use caulk or foam to air seal.

In our follow-up post we cover how air leakage is measured with a blower door test and what a good target is.