On June 12th our Dorchester DER (deep energy retrofit) had its first open house. This was to show people in the industry (convention general contractors, green builders), neighbors, and anyone else interested in the DER program what, how, and why we took the approach that we did. Oliver Klien from National Grid was present to discuss how National Grid is steadily moving forward with their pilot program and how people can take advantage of the incentives. Additionally, Green Bean Development and Rhode Architect fielded questions on design and future plans for the dwelling.

We had a strong showing of about 65 people that visited and took the tour of the site. (In the photo) The tour began in the first floor living room where Brian Butler (owner of BGB) explained why we were building to this extreme and how we were able to achieve such extreme objectives. In this area, visitors were able to see the “guts” of the building, meaning the raw interior framing with some of the insulation installed. As we then moved outside, our progress on the exterior work became evident. At this stage, all of the rigid insulation and R-5 windows had been installed, giving the viewers insight into our air-sealing campaigns and the different types of insulation that had been used in different areas.

In order to complete the DER program, houses are required to provide three open houses to show the various phases of the projects, and more importantly, to education the community. Akin to the distinctiveness of each DER, these open houses are all unique, reflecting the varied techniques and execution necessitated by the individuality of old homes. In this project, Green Bean Development was dedicated to fulfilling several primary objectives, including:

  • Taking a rundown old Victorian and not only renovating it, but also improving its efficiency by 60-75% in order to complete the DER requirements
  • Converting approximately 3,800 square feet of living space into three units, each with open spaces, a modern feel, and great blend of historic and updated finishes
  • Helping to revitalize a neighborhood where both Green Bean and Rhode currently have residents
  • All the while, keeping to a strict budget.

Budget is a major factor in every project. When completing a DER on a 3-story, 3,800 sq ft Victorian, the insulation budget alone can be tough to swallow. Our original budget to complete all the interior insulation using a combination of open and closed-cell foam was some where in the range of $30k. Green Bean wanted options to reduce the costs and value-engineer this large price tag. With the help of an energy consultant, a sensible technique was developed that allowed us to reach the DER requirements and slash the $33k to just $16k. This reduction was made possible by using a large amount of a fiberglass insulation called EcoBatt, as shown in the pictures below. This material was used in all the sidewalls of the dwelling except for the gable-ends. Balancing the insulation requirements with historic character, we had to use only one layer of Poly-Iso 2″ rigid insulation to preserve the soffit depth. In-turn, we needed to add a 2″ layer of closed-cell spray to the interior of the gable walls. With the remaining 2.5″ cavity left in the gable walls, fiberglass batt insulation was installed to reach the R-value needed.

We used a similar process for insulating the roof slopes of the 3rd floor. Additional framing was also required here to extend the existing 2″x 8″ roof rafter to a 12″ depth. We accomplished this by attaching plywood gussets to the existing rafters and then adding a 2″x 6″ with a small gap or air space between the to 2″x’s to eliminate the thermal bridge. The first 8″ was filled with closed-cell foam and the remaining cavity was then filled with EcoBatt once again. Throughout the project, closed-cell proved valuable in solving issues with clearance, thermal bridging, and air-infiltration in areas of concern.

Please make sure to see us at our next open house in Dorchester, or maybe stop by one of our other DER’s as they are scheduled.


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