Well we got through our design charrette today. For those of you who may be unfamiliar with this term, charrette comes from the French for a wagon or carriage. Back in the day, French architectural students would cram into the carriage and would work madly to finish their sketches before arriving at class. Today a design charrette is a day of brainstorming and throwing ideas out on the table for discussion. For the purposes of LEED it the day when the team considers all of the available points that can be pursued, and they rate which points are achievable, not achievable and those maybe points that are worthy of further consideration.
Integrated Design
The key to making this work is having as many people from the project team present as is possible. Today we had Dave from Lindhout Architect's present, as well as Tom and Joannée from Stone Coop, myself as Owner's rep, Tom Boyle our builder, Mike from Alliance for Environmental Sustainability, Alex our Green Rater, Scott our HERS rater/energy modeler, John Boylan from Lakeside Heating & Cooling and Brent Deline our framing contractor. Everybody had a chance to comment on the credits and discuss possible strategies.
The idea in getting everyone on board early is to have the team influence the design early on rather than reacting to design on the jobsite. Everyone has a clear understanding of the goals early on and they have had an opportunity to discuss how all of the parts and pieces go together. Rather than the old fashioned way, getting to the jobsite and having several people scratching their heads trying to figure out what the designers were trying to accomplish.
The Checklist
I don't have a final copy of the checklist yet but I will post as soon as I do. We were shooting for a number in the 70's which would put us solidly in the Gold category. We ended up at 84 pts only 6 points away from Platinum. We have a fair number of points in the maybe column that we can pull on for the other 6.
Here's a short list of some of the major strategies we are attempting:
- Smart Framing - We'll be using 2x6 stud walls spaced 24" on center. This will allow fewer studs in the wall which increases the area for insulation and uses less wood. Also part of this framing method is to not double up on studs around windows and doors (trimmer studs) and to properly size headers for the anticipated load and on non-load bearing walls you don't use a header.
- Outsulation v. Insulation - We will be using a 1/2" structural insulated sheathing on the exterior walls, no osb, with and additional 2" of R-10 rigid foam insulation over that. We're shooting for an R-30, R-35 wall. All seams will be taped or glued to create a really tight air barrier. The problem with wood on the exterior of the structure is that when the house is warm in the winter, the wood sheathing is warm on one side and cold on the other. This creates a place for water vapor to collect. With a long enough summer and good ventilation the sheathing will dry. But enough cycles of this creates a potential problem. We're still discussing the wall cavity insulation.
- Roof Insulation - The roof will consist of a foam insulation sealing the truss chords and the ceiling drywall. Then we will blow in insulation over that. We are shooting for approximately R50 in the roof.
- Heating/Cooling - Ductless heat pump system. Very high efficiency, SEER 18, and no duct work. There is a condensor unit located on the exterior of the house and then 3 - 4 fan units inside. A Tulikivi masonry heater. Essentially a 3,000 lb soapstone fireplace that, with 2 hours of burn time, will radiate heat for 24 hours.
I'll get some more up this week end. I'll try and get more photos up as well.
Joannée as architect.
