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Deep Energy Retrofit suggestions

[email protected] | Posted in Energy Efficiency and Durability on

I have been funded to do a renovation and deep energy retrofit to a 3100-sf Ranger Station built in 1969.  A simple frame structure with a walk out basement.  Currently I am preparing a “Design Guidance” document to hand off to the A&E consultant to guide their design efforts. What I’m including is:

             The climate data and solar exposure data for the site, to assist in determining energy needs/usage. 

             Our desires for the outcome.  Is that the building become a model of the Wilderness Urban Interface code to demonstrate that conforming buildings can look good.  The Forest Service is required to comply with the ICC codes with out modification.  And not subject to local permitting or code enforcement. 

Briefly, Dual pane windows were installed in around 2000, all of them have lost the seal.  The siding is original cedar, the original shake roof has been redone in PBR Pattern metal.  The basement was finished in 2004, as office space.  There are 2×4 walls with fiberglass batt insulation, with a 2-inch clear space between the wall and the concrete basement walls.  The HVAC systems draw exterior makeup air from vents in the concrete walls and bring it halfway around the building to keep the space between the two walls from getting too damp.  There is a serious problem with water coming in the joint between the basement slab and the walls, every spring as the ice in the soil melts.  When they did the basement remodel, they added egress wells, and larger windows.  The window wells extend past the eave line and will fill completely during thunderstorms.  Water, and ice from the roof fall into the window wells in the spring as things thaw off the roof. 

The existing heating is base board hydronics, which were rule of thumbed, not sized, and only have fins under windows, (It doesn’t work very well).  With forced air ventilation for the AC in the summer.  The thought is to replace the existing systems, with high efficiency air to air heat pumps.  I installed an air-to-air system on one of the other offices about 6-years ago.  The only time the backup strips have been on is if someone comes in outside of normal hours and bumps the thermostat up.  The control system has an exterior heat sensor in the compressor unit and has learned the heat signature of the building.  It calculates when to start in the morning to arrive at the target temperature during the occupied period.  I’m thinking of something similar for this renovation. 

The basement will have to be excavated down to the slab, to remove a couple of old fuel oil tanks, and seal the slab to wall joint.  So, I’m thinking of adding exterior foam insulation on the basement walls.  That will be far easier than removing interior walls to insulate the interior.

All the siding, trim and windows will be replaced due to age.  So, I’m think of insulating the exterior of the framed walls and extending the new windows out to the new exterior surface.  Siding will be cementitious lap siding; windows will be efficient for the climate and exposure.  I’ll let the A&E firm make that recommendation. 

To extend the eave line, I’m thinking of installing 10-inch SIPs to extend the eave line and convert the attic to conditioned space. 

Anyone have any suggestions of other things we should be looking at?

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