BrightBuilt Barn: a Super Green, Prefab, LEED Platinum Net-Zero Building

Robin Tannenbaum

Diagram Showing Panel Composition

With our commitment to using an insulated panel made, we began to investigate what this panel would be.

A rigid foam panel solution?
Peter Warren connected us with a local panel and truss manufacturer who makes panels with integrated windows and siding all the time. Historically, these rigid foam panels are framed with steel and while they may have finish materials and/or windows installed in the factory, they are all for new construction where everything is fresh and new and walls and floors are guaranteed to be plumb and square. Given that the panels we are asking for would have to coordinate with existing conditions, the company was nervous about pre-installing windows in the panels, for fear of the two not lining up. In addition, this company planned to purchase most of the panels from a third party (Hunter Panels) and simply glue on an additional layer of OSB in their factory. While we were grateful to this company for exploring the idea with us, this did not ultimately feel like the innovative solution we were seeking.

Cellulose Panels with Keiser Homes
We turned to our friends at Keiser Homes, with whom we have been developing modular net zero homes. Keiser is a m

Working Out Details with Porter Panel, KTA and Peter Warren

odular builder who delivers their homes as boxes that include stick framed walls, sheathed on both sides and filled with cellulose, windows installed. Keiser was excited by the challenge we posed to them and has risen to the challenge. We have been working closely with Joe Martin at Keiser to develop a plan and details for how these panels will actually be constructed, brought to the site and attached to the house.

Here are the answers to some basic questions about these panels.

What is the composition of the panels?
These are 2×8 panels with a ½” layer of OSB sheathing on each side. The entire panel will be filled with dense pack cellulose for a R-26 (7 ¼” x R-3.6 per inch). We are still working the siding detail out with Keiser but it is our strong desire that vertical vinyl siding will be attached to the panels in the factory, over a layer of house wrap.

How are the panels attached to the house?
A galvanized metal angle will be attached to the sill of the building. The lower panel on each elevation will rest on the angle and be tipped up into place, directly against the exposed sheathing of the original building. The panel will be attached to the angle at it’s base and to another angle attached to the second floor rim joist of the building at the top. The next panel will sit on top of the second angle, be toe-screwed into the panel below and attached to a building fastened clip at the top.

How big are the panels?
Keiser is only limited by the size of their trucks which are 60’ long so we will try to cover the South and North (long) sides of the buildings with 2 panels each, 40’ +/- long and 8’-9’ tall. We will take final field measurements with a laser and will use the leveling angle as a zero point for all dimensions. The panels will be lifted off of the trucks and moved into place by crane. It’s going to be something to see!

What about the windows?
Windows will be installed in the panel at the Keiser factory. We will take the field measurements for all rough openings and decreased them by roughly ½” on all sides, when sizing the new windows. That way, any inconsistencies in the new and old windows lining up, resulting from the building being out of plumb due to age, can be accommodated in that extra ½” of space. Peter’s crew will pre-construct a series of window bucks for each unit that can be slid into place once the panel is set. Foam insulation will fill in the space between the buck and the R.O.

Here are some of the drawings we are using for pricing purposes, which show how the panels will go together and be attached to the house.

Put A Sweater On That Building!

Detail of Galvanized Angle Meeting Building and Panel

Window In The Panel - Head and Sill Details

Robin Tannenbaum

By now the fundamentals of accomplishing a Deep Energy Retrofit have been stated over and over again – air sealing, insulation, better windows, and mechanical ventilation. But there are many ways to accomplish each of these primary components — What exactly does air sealing mean? What kind of insulation? Which windows? How do you integrate ventilation into a house that has none? What is the proper insulation installation method?

We are tackling each of these questions at Victory Avenue. This week’s focus? We are honing in on insulation. There are so many kinds of insulation to choose from (fiberglass, cellulose, spray foam, rigid foam) each with their own pros and cons and each achieving different R-Values or levels of resistance to the transfer of heat.

We decided early on that we would not add more insulation into the existing stud and rafter bays. Through some selective poking around we determined that a small amount of insulation already exists in portions of the building — old fiberglass batts in the wall stud bays and between ceiling rafters – none of it fully filling the bays it occupies and much of it turning black as a result of too much air flow around it. There is also some settled cellulose on the floor of the eaves behind the knee walls.

To fill those bays with new cellulose insulation would require removing the existing batt insulation so that the new insulation can be packed in tightly for maximum efficiency. After lots of querying we confirmed that there is not yet an effective, efficient process for removing existing insulation. The options that exist are time consuming and disruptive to the building and don’t guarantee full clean removal of the insulation, which would compromise the performance of any new insulation added. In addition, our contractor worried that blowing insulation into the bays ran the risk of triggering problems on the inside of the building if any weak spots on the insulation gave out under the pressure of the new blown in insulation.

So we turned our attention to adding insulation to the outside of the building. The question then became how? The most straightforward method would be to use 4’x8’ sheets of rigid insulation attached individually to the outside of the building and cut on site to fit the size and shape of the building. This is done commonly and is fairly straightforward. However, this is the BrightBuilt Retrofit and our guiding principles include innovation and replicability so back to the drawing board we went.

Again with the assistance of our contractor, Peter Warren, we developed the idea of insulated panels that could be attached to the house. Innovative? Getting there, but this has been done before so we kept talking – what would take this process a step further than it has gone before.

We landed on the idea of the panels arriving on site with the new windows already installed. In fact, what if the siding is already installed? In our vision, an entirely ready to go panel could arrive on site on the back of a transporter and be lifted (by crane) into place on the house – essentially placing a fully dressed shell around the existing building. By including the windows and siding in the panels prior to installation, the actual time on site and disruption to the building occupants is minimized. One can begin to imagine a future scenario in which a homeowner simply places an order for a new skin for their home and it arrives, built to their specifications, and is lifted into place and attached to the house in one fell swoop.

Innovative? Replicable? We hope so. Check back later this week for a post about how the panels themselves are made and attached to the building.

Robin Tannenbaum

The second technical charette was very productive! 55 or so folks gathered around to talk about the project, ask us tough questions and poke holes in our assumptions! The big new idea we introduced is having insulated panels pre-made off site, based on and installed in one big move in one day. More on this soon!

Morgan Law in our office modeled various insulation upgrades scenarios using Passivhaus modeling software and Diane Milliken from Horizon Residential Energy modeled the same scenarios in REM/Rate. The results were stunningly aligned, an interesting topic in itself, and consistently showed 82%-86% reductions in energy consumption based on the scenarios we are considering.

The biggest topic of conversation was how to treat the west wall of the building which is hard to access for insulation. Our energy models showed little impact on the overall energy performance of the building, if that one wall was not insulated, but experience and reality tells us that leaving 1/4 of the wall surface of the building un-touched is not smart.

Robin Tannenbaum

We are holding a second Technical Charette on Tuesday June 7 at Maine Green Building Supply.

Martin Holladay, the Senior Editor of Green Building Advisor and BrightBuilt Retrofit Board Member, will join us for a detailed exploration of insulation and technical detailing strategies for this 3,000 sf 1946 house which is typical of Maine residential construction.  A major goal of this project is innovation and we will also be talking about the  feasibility and replicability of adding insulated panels to the outside of the house as a retrofit strategy.  
 
We welcome the input of all design and building professionals – participation in the first Charette is not required.  And hey, we’ll provide food!

Robin Tannenbaum

Last week the Building Science Discussion Group at Maine Green Building Supply graciously hosted a BBR/CPI technical charette as part of their monthly discussion group. A major storm was blowing in that evening but 25 brave souls braved the weather to participate. Discussion was focused but lively. We discussed pros and cons of adding 4″ of rigid insulation to the building envelope versus a Larsen Truss filled with cellulose. (I wonder if we could do one side one way and one side the other to compare the relative costs and ease of each method.) One big new idea that came up was to complete the building envelope at the floor of the first floor and isolate the basement so as not to have to deal with moisture mitigation and other unknowns in the basement.

Extremely helpful was having Diane from Horizon Residential Energy on board to do some live energy modeling of scenarios we discussed. Essentially, the house is poorly insulated/air sealed enough that an effort at fairly low hanging fruit would quickly make a 50% improvement in overall energy consumption. The question then becomes, whether 50% is enough of an improvement and if the percentage is even as important as the number, the AMOUNT of energy itself.

Robin Tannenbaum

We had an energy audit conducted towards the end of the 2010 to help us gauge current conditions at the house and to help us establish a baseline for improvements. The blower door test showed an ACHn (Natural Air Changes) of .41. Suffice it to say, there is some room for improvement! Here is our auditor, Diane Milliken of Horizon Residential Energy Services conducting the blower door test assisted by one of the people who lives at the house.

Robin Tannenbaum

Here is a pretty good article from the NY Times about simple steps people can take to tighten up their own houses. Note the $75 cost of an energy audit in Connecticut. I’m told that since it is a wealthier state (than Maine) the state subsidizes the audits. Here is Maine audits for 2,000-3,000 sf houses are typically between $400 – $600.

Robin Tannenbaum

Anyone who has ever been job hunting has heard the expression “Elevator Speech.” This is the 30 second description of what it is you do that you use to introduce yourself to people who may be of assistance to you. The goal is to be short, sweet and concise. At our kick off charette, we decided we needed the equivalent of an elevator speech to describe the BBR/CPI project to folks who aren’t familiar with it. We had some back and forth and here is what we came up with:

An innovative partnership between Community Partners, Inc. (CPI) and Kaplan Thompson Architects will save taxpayer dollars through the Deep Energy Retrofit of an existing CPI home. It will be a model for communities in cold climates to educate home-owners about effective home weatherization. What is a Deep Energy Retrofit? It is an effort to go far beyond other weatherization projects by taking a whole house approach which upgrades the building shell, windows, heating system and ventilation. Taken together these improvements can reduce the home’s energy consumption by 50% – 90%.

What do you think?

Robin Tannenbaum

We are starting work with Community Partners.  Last week, we held a Kick-Off Charette with some of the key CPI folks who will be involved in the project.  The goal of that charette was to talk about how we will all define success for the project and to learn more about what we all want to get out of the experience.  Now we are working towards a technical charette in early January, where we will gather experts in various aspects of deep energy retrofits in one room and get down to some of the nuts and bolts of the projects.  We continue to want input from the interested general public – what are YOUR ideas for keeping folks like you involved in the process as we move forward?

Robin Tannenbaum