This March marked the 16th year for the Building Energy trade show and conference in Boston, Mass., put on by The Northeast Sustainable Energy Association (NESEA). Your reporter caught the train to the World Trade Center in Boston's rapidly developing Seaport District to attend “BE16” and to bring you this report.
NESEA’s roots date back to the oil crisis days of 1974, when a group of builders, architects, engineers, and homeowners organized as the New England Solar Energy Association in hopes of reducing the region’s reliance on imported oil. Over the decades, the group’s geographic base and its scope of interest have expanded, resulting in the current organization: a professional association whose members’ interests, professional roles, and practice areas span a broad range in the field of building energy, including not just residential design or construction, but commercial and institutional specialties as well.
Educational sessions at this year’s conference spanned the same broad spectrum. No single observer can sum up the whole smorgasbord; but a random walk through the conference offerings was well worth the time spent. Here’s a collection of snapshots to give you the flavor.
Small Airflows, Small Measurements
If you build tight houses, you have to think about providing fresh air. In a lively session titled “Moving Beyond Faith Based Ventilation,” old-school guru Terry Brennan teamed up with New York City Passive House young bloods Cramer Silkworth and David White to take a close look at how air ducts and fans actually perform (as compared to how designers and builders hope they’re going to perform). Brennan — himself a member of the ASHRAE committee that writes rules for residential ventilation — started with a brief history of recommendations for ventilation airflow rates, dating back as far as the mid-1500s (when a German scientist devised a bellows system to send fresh air into underground mines). Then the audience got involved, as Brennan, White, and Silkworth broke out a whole assortment of specialized devices and measured the airflow in a small demonstration duct assembly.
The results from one measurement to the next seemed pretty consistent, as long as the team was using the same device. But from one method to the next, measurements seemed to vary by as much as 30% — evidence, if any was needed, that airflows are hard to pin down precisely. The exercise lent some support to an approach long advocated by building scientist Joe Lstiburek: Size the system to provide a range of flows from 30% below the ASHRAE standard to 30% above it, and then let the homeowner set the dial based on comfort.
Big Buildings, Big Choices
If you’re interested in big buildings, BE16 gave you plenty to think about, and a lot of chances to learn. One high-value offering was a three-hour pre-conference session presented by well-known Passive House designer and consultant Adam Cohen. Cohen discussed methods and approaches he says can help large-scale structures pass tough Passive House metrics at costs that are competitive with conventional code-compliant construction.
Other presenters zoomed in on high-performance details. In a full-day session on air leakage, Larry Harmon of Air Barrier Solutions detailed the lessons learned from years of retrofit air-sealing work on millions of square feet of commercial and institutional buildings. And in a session called “Break It or Lose It,” building performance experts Andrea Love and Jeffrey Abramson focused on thermal bridging, analyzing infrared images from the facade details of university buildings and office complexes, and discussing practical ways to stop the bleeding.
When it comes to budgets, the world of big buildings can be a tough environment. Architect Jesse Thompson of Kaplan Thompson Architects (KTA) told an interesting tale of cost-cutting in a session called “Huddle Together for Warmth.” KTA won a Deutsche Bank design competition with its proposal for “Bayside Anchor” (left), a public housing project in Portland, Maine. Then, successive reviews by Maine’s public housing authority forced the designers to implement two brutal rounds of cost-cutting. Heat pumps were scrapped in favor of electric resistance strip heating; exterior rigid insulation got the ax in favor of double walls with fiber insulation. But the project survived — and in fact, is still in the running to achieve Passive House certification (at least on paper).
Thompson used the project example to shed some light on the differences between the original Passive House standard created by Europe-based Passive House International (PHI) and the evolving U.S. standard authored by Passive House Institute U.S. (PHIUS). Under the old European method, the Bayside Anchor project didn’t make the cut. But under the new PHIUS rules, which measure allowable energy use based on energy use per occupant instead of per square foot, the affordable project’s high density made the difference, and the project passed.
But will the contractors on the job be able to actually deliver the promised results, despite the shaved-down details? “Yeah,” said Thompson with a grin … “I hope so. We’ll see.”
Big Power From Small Sources
Individual buildings represent a key to modulating energy demand. But increasingly, buildings are also a factor in power supply: roof-mounted photovoltaics have come down in cost to levels that make on-site power generation a serious alternative to investing in energy conservation. But there’s a catch: integrating all those rooftop micro-generators with the regional power grid is no simple matter. On the other hand, a technical solution for that problem is also in view: home-scale energy storage using batteries — which, like PV panels, are dropping in price as technology advances and production ramps up. Two back-to-back sessions at NESEA addressed that big policy challenge and the growing opportunities, with presenters including Judith Judson from the Massachusetts Department of Energy, Todd Olinsky-Paul from the Clean Energy States Alliance, and Betty Watson from SolarCity.
Big Data From Small Devices
If small power sources are starting to have big implications, the same can be said of small information sources. In one of the most thought-provoking sessions at the conference, data wizard Michael Blasnik presented aggregated data collected and reported by millions of smart Nest thermostats now installed around the United States. Nest thermostats collect data on indoor and outdoor conditions and heating and cooling system operation every few seconds, and report all the info to a central data collection system. Their motion sensors even record when the house is occupied and when it’s empty. The result is a huge pool of precise, detailed data on how mechanical systems function in real houses. Blasnik has access to the aggregated information, and his analysis of the data reveals many intriguing questions, and possibly some answers. (Google, by the way, which now owns Nest, does not have access to the data, according to Blasnik.)
One interesting angle: Blasnik observes that while air conditioners in the U.S. are typically oversized in theory, they may be undersized in practice, because of the way people operate their houses. A system may be well designed for keeping the house at the constant design temperature; but if the owners turn the system off when they go to work and then expect it to quickly cool the house by five or ten degrees as soon as they get home, the system will struggle. That evening demand surge could be contributing to peak load problems for the whole power grid in warm climates.
Another puzzling observation: heating system run times seem to be about the same in much of the U.S., from milder states like Kentucky or Tennessee right up to northern locations like Wisconsin and upstate New York. Apparently, the variation in levels of insulation cancels out the difference in climate, leaving heating systems to cope with much the same load in houses across a wide range of environmental conditions.
Flat Roofs, Steep Roofs
It wouldn’t be an energy conference without some frank discussion about bulk water leakage. In a jam-packed two-part session, Building Science Corporation expert Kohta Ueno teamed up with consultant Peter Marciano for a detail-filled discussion that spanned the worlds of low-rise residential and mid-rise commercial roofing. Marciano drew from decades of field experience building and repairing flat roofs, parapets, and facades, while Ueno discussed his organization’s industry-leading research into the field performance of unvented cathedral roof construction and insulation alternatives. A flat ceiling with attic floor insulation and a ventilated attic, Ueno observed, is clearly the safer choice. But the problem of bringing hvac air handlers and ductwork within the insulated and air-sealed envelope leads naturally to the option of the insulated and air-sealed roof plane — and that brings on the challenge of creating robust details for the insulated rafter system.
One general observation that seems to apply to both flat and sloped unvented roofs: solving the building science issues of an unvented assembly is much easier if you put rigid insulation outboard of the framing and the fiber-insulated cavities. It’s when you deliberately exclude the option of rigid sheet insulation that you start to encounter the really tricky moisture and air leakage risks.
Small Talk About the Big Picture
At this kind of get-together, a lot of the action happens in casual interactions among two or three people at a time. In one interesting example, your reporter happened to overhear as a graduate student researcher quizzed two well-known geeked-out experts about the Department of Energy’s new “Home Energy Score,” which bills itself as something like a miles-per-gallon (MPG) rating for houses. Both experts threw some cold water on DOE’s concept. One pointed out that by aggregating different aspects of home performance into a single score, the method tends to obscure as much as it reveals, in what the expert described as a “concatenation of concatenations.” “The house may score a 5, but it might have a 9 for source energy use and a 3 for global warming potential of materials,” he said. “Well, what if I’m mostly interested in global warming potential? This 5 tells me nothing.” And he pointed out that in practice, houses vary widely in terms of which practical measures might actually reduce their energy use, and what those measures might cost. A general score doesn’t offer much useful guidance for a homeowner who needs cost-effective specific solutions.
Another expert questioned the scoring system’s practical utility for its main objective: motivating conservation efforts. The problem, he argued, is calibration. “As an actual metric the score is meaningless,” he said — “the whole point is to motivate homeowners to upgrade their houses. But I’ve seen cases where a homeowner gets an 8, and then they spend $5,000 on conservation, and they still score an 8. In that case it’s counterproductive — it actually de-motivates the consumer from doing something good.” That discussion is far from over, but it does indicate that the DOE’s new marketing tool has a long way to go to earn any street cred in the energy geek community.
In general, our dip into NESEA’s waters revealed an energy-efficiency world in flux. While the future is uncertain, what’s clear is that things are changing fast. Checking in at the NESEA conference every year continues to be a great way to keep tabs on that rapidly evolving sector of the homebuilding industry.