Game Changers in Building Science

Thank you to everyone who stopped by our booth last week at Greenbuild 2015 in Washington, D.C.! By all accounts, this year’s event was a great success. In case you missed it, our fearless leader, Steven Winter, spoke at the GAF booth on Wednesday. As an architect who has been practicing building science for the past 50 years, he shared insights about some building science innovations that he thinks have been “game changers” and have intrigued him: they are changing the way we design, build and operate buildings.

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Here are the highlights:

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Heat Pumps Are Taking Over

Air-source heat pumps are a booming business. In the Northeast, manufacturers report that sales of residential systems have increased by 25-35% per year over the past 5-10 years. We’ve seen more and more systems being installed in existing homes (to provide cooling while offsetting oil or propane used for heating) and into new homes (often as the sole source of heating and cooling).

We’ve looked into these systems often, and from many perspectives. I’m planning a series of posts, but, for now, here are the answers to some basic questions we receive from clients.

First, the basics: What is an air-source heat pump (ASHP)?

It’s an air conditioner that can operate in reverse. During the summer, it moves heat from indoors to outdoors. In the winter, it moves heat from outdoors to indoors. We helped NEEP (the Northeast Energy Efficiency Partnerships) to put together a market assessment and strategy report on ASHPs. The early sections in this document (see p. 12) outline the different terms and types of heat pumps (ducted/ductless, split/packaged, mini-split, multi-split, central, etc.) Unfortunately, different people can use the same term to mean different things, but hopefully the NEEP Northeast/Mid-Atlantic Air-Source Heat Pump Strategies Report can help clarify things.

Indoor section of heat pump.

 

Outdoor section of a heat pump.

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Tackling the DC Green Building Code: Resources for Code Compliance

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 

Green Building DisplaysYour 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  Read more

Accessible Design: Common Mistakes & How to Avoid Them

Part 2: Dwelling Units

As promised, we’re back with Part 2 of the most common mistakes that our accessibility group encounters when assessing for compliance with regulatory requirements for accessible design and construction. This time, we’ll focus on frequent problems that we have encountered within dwelling units. Remember, in order to save time and money on costly remediation once construction begins – and reduce the risk of exposure to future litigation – it is best to tackle these issues early in the design phase.

Here are just a few of the violations frequently identified by our inspectors:

1.  Doors: Clear Width

Clear width is measured between the face of the door and the opposing stop, when the door is open 90 degrees.

Clear width is measured between the face of the door and the opposing stop, when the door is open 90 degrees.

Every door within a dwelling unit that is intended for user passage must provide the necessary clear opening to  provide access to a person with a wheelchair, or other mobility aid. The minimum clear width requirement varies (32 inches nominal or 32 inches minimum), so it is important to consult federal, state, and local codes to ensure that the specified doors will comply. This requirement applies to all doors within the unit – it does not matter whether there are multiple doors providing access to a particular room.

Specifying user passage doors that are 3’-0” or 2’-11”, including doors to closets deeper than 24 inches, will help to ensure that a compliant clear width is achieved.

2.  Kitchen Clearance

Projecting appliances often encroach into the required clearance in dwelling unit kitchens.

Projecting appliances often encroach into the required clearance in dwelling unit kitchens.

The minimum clearance between opposing elements in a kitchen depends on whether the kitchen is a galley kitchen (40 inches) or a U-shaped kitchen (60 inches). Clearance is measured between the furthest projecting element of opposing countertops, appliances (excluding handles), and base cabinets.

Often, the range and refrigerator are not aligned with the edge of the countertop, as commonly drawn on plans. These appliances frequently project beyond the edge of the countertop and often compromise the required minimum clearance. If larger appliances are selected (or substituted) after kitchen layouts have been designed, it is important that the layouts are reassessed with the updated appliance dimensions to ensure that clearances are maintained.

3. Outlets, Switches, and Environmental Controls

Switches, electrical outlets, thermostats, and other controls intended to be used by the resident must be located within accessible reach range. Noncompliance often occurs when reaching over an obstruction to access the controls is required (e.g., kitchen countertops). Often, electrical subcontractors install light switches and outlets at a consistent height, which while compliant for an outlet mounted on a wall in the middle of the room, will not necessarily work for an outlet mounted over a counter. We highly recommend installing all switches, outlets, and other controls no more than 44 inches above the finished floor, measured to the top of the electrical box.

Dimensioning to the top of the electrical box for outlets mounted high on the wall and the bottom of the electrical box for outlets mounted low on the wall will ensure that all operable parts are fully mounted within accessible reach range.

It is never too soon to think about accessible design requirements. The earlier these common problem areas are taken into consideration, the easier it will be to ensure compliance with accessibility laws and regulations once the construction phase of the project begins. By planning ahead, it is possible to address the most widespread issues in the design phase, significantly reducing the amount of delays in the field. A little effort now could eliminate a lot of headaches later.

Air Sealing with Open Cell Spray Foam Insulation – Know the Risks

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.

ocSFP Window Flashing

While this wall assembly was not insulated with ocSPF, poor window flashing details are a common issue that we see and is one of the reasons we are cautious with this insulation approach.

  • 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…  Read more