Zero net energy is no easy goal to attain
When it comes to energy, it isn't easy or inexpensive to be green and, at least according to one speaker at a recent gathering, not all that exciting to talk about either.
Even as chairs were being set up and a computer-driven Power Point presentation was fired up, speaker Marc Rosenbaum was admitting that his presentation was going to be boring. Yet about 50 Vineyard architects, builders, contractors and a smattering of interested listeners sat through the program at the Chilmark Community Center.
The talk titled "Zero net energy homes, deep energy retrofits and passive homes - a view from the bleeding edge," featured five residential retrofit projects undertaken by Mr. Rosenbaum's company Energysmiths, headquartered in New Hampshire. A systems engineer, Mr. Rosenbaum has worked for 20 years with South Mountain Company of West Tisbury on the Vineyard.
Mr. Rosenbaum's slide show began with the explanation of terms.
A "zero net energy home" is one that generates as much energy as it uses over the course of a year.
A "zero energy home" always makes or creates as much energy as it needs.
A "passive home" and is a trademarked name for structures that were created in Germany to a set of rigid standards that cause it to be a very low energy user but not necessarily a zero net or zero energy home.
The presentation focused on a "show and tell" of the zero net energy homes as Mr. Rosenbaum admitted, " I do not know how to do it..." referring to the building or retrofitting of a zero energy home. And, there are only a few passive energy homes in the U.S. (including the Andre House in West Tisbury) because the existing technology and energy saving construction standards in the United States lag behind those in Europe.
A "deep energy retrofit" is intended to bring an existing home to the level of energy efficiency that you would find in a "superinsulated" new house. "Superinsulated" is a term created about 35 years ago, according to Mr. Rosenbaum, that describes a home that is two to three times as insulated as a traditional home.
Amidst slides loaded with engineering acronyms, tables, diagrams and flow charts, the audience learned that regardless of the project the process is the same. Initially Mr. Rosenbaum will study a home's existing fuel bill, create an energy model that demonstrates current energy usage, and establish a goal for the post-retrofit. Then he sketches the house with the efficiencies desired and finally translates the sketches into action steps.
Most often the action steps include improving insulation by use of lots and lots of new, sprayed-in formaldehyde. "This is not the formaldehyde of 35 years ago," Mr. Rosenbaum explained when asked about the dangerous fumes often associated with the older material. Oftentimes, utilities must be moved, old and ineffective windows replaced and, when properly positioned, solar panels for water heating and electricity installed.
Among the examples shared was the Davis House in Chilmark which is now, following its retrofit, powered by renewable energy. It has a passive solar design (utilizing solar for hot water and electricity) with two wood burning pellet stoves and superinsulation. The home also has a number of meters that measure energy use.
The Moomaw House in Williamstown has achieved a "zero net" status by getting the energy load, or demand, very, very low, according to Mr. Rosenbaum. Even with a well-thought out and executed retrofit, Mr. Rosenbaum explained that "there is so such thing as zero energy houses; there are only zero energy families."
Still the Moomaw House faces south, capitalizing on a lot of glass, has superinsulation and a heat recovery ventilation system. The house utilizes triple-glazed glass with a special coating, has low-flow water fixtures, efficient lighting and appliances and "conscious occupants," according to the presentation.
According to Mr. Rosenbaum, choosing windows is complex. He modeled six glazing options in this home because "the type of glass selected could make a 30 percent difference in the amount of light allowed in (translating into heat) versus the amount of insulation created." According to Mr. Rosenbaum, the difference between a house that is "pretty tight" compared to "very tight" can amount to a 30-percent energy savings.
The presentation was interrupted by a few questions, most of them about the cost of a project being shown on the slide screen. In one instance, Mr. Rosenbaum responded, "I don't know. I do not know until you tell me what the fuel replacement cost is going to be over the next 20 years."
Without a crystal ball, Mr. Rosenbaum said that you can never tell what the cost or savings of a retrofit project has been. "The goal," he said, is "to make a home more energy efficient and cause the house to last longer."
According to Mr. Rosenbaum, "part of what drives these retrofits is looking at what you have to work with." He tries to retain roof overhangs and siding whenever possible, for example. The increased life expectancy of a building is created by more durable materials, greater "rain handling capacity" and better windows which will mean less maintenance for the next 50 years, he said.
The before and after of another deep energy retrofit of a 1970s- style ranch home in Holderness, New Hampshire, was also discussed. Again, Mr. Rosenbaum was asked what the project cost. "A lot," he said.
Mr. Rosenbaum's Power Point show included pictures and discussion of the affordable housing project at 250 State Road in West Tisbury where eight new homes are currently under construction. The project has the homes clustered close together for efficiencies and facing south so that a 5 kilowatt solar electric system can be utilized in each. Heat recovery ventilation and low-flow water fixtures will be utilized as well as efficient lighting and appliances.
Each affordable house is only 1,200 square feet, and will be superinsulated to create "extreme air tightness" and there will be "more insulation in the basements than in most homes," according to Mr. Rosenbaum. Eaves have been added to the homes to help seal the structures as well as shade the exterior. "Every bit of insulation helps," Mr. Rosenbaum said. "The only way to get to zero means lots of insulation."
At least one of the homes included in the program went beyond the concept of retrofitting and was gutted to bring it to the level of energy efficiency the homeowner wanted. "Retrofitting," Mr. Rosenbaum explained, is done from the outside; "gutting" is performed on the inside and avoided whenever possible as it forces the homeowners to move out while the work is in under way.
"We have a lot of buildings we can abandon and feel good about, but we also have a lot of buildings that we can fix," Mr. Rosenbaum concluded to a smattering of applause.
