1 Low-cost Construction for High-energy Savings Brian J. Wimmer Construction Manager Rochester Area Habitat for Humanity
2 Objectives: 1. Control air & moisture in high-performance, low-cost construction 2. Basics at design stage of house 3. Material options (insulation, windows, mechanicals, etc.) for high-performing homes 4. Improve basics & modified techniques before hightech solutions 5. ENERGY STAR for Homes process & checklists 6. Performance measures in diagnostic testing 7. Assess energy use in completed homes
3 What does it take to build an energy-efficient home? 1) Labor u Standard methods, OVE, new best practices u Devil in the details 2) Materials u Energy-efficient u Durable u Wet/dry? u Over time u Maintaining Durability
5 The climate throws a lot at us Are we building ships? It may make for natural beauty but in our homes it conspires to undo our work!
6 Control air & moisture in highperformance, low-cost construction u u u Top cause of heat and moisture movement is air flow Preventing heat and moisture flow through the foundation system Preventing heat and air flow through the building envelope u Follow up after sheetrock installation, attic and walls u u u u Sealing doors and window openings Air-tight framing methods Framing to foundation transition Air-sealing the attic
7 Control in the wall assembly Outside Inside Heat Summer Moisture Control Wall Assembly Control Heat Winter Moisture
8 #1 Means of heat & moisture transfer in wall assemblies is: Air Flow
9 Stop the air flow! And stop the heat loss & the moisture damage Control Air Flow Control
10 From constructioninstruction.com u The reality: Many walls have too little insulation and too many leaks. This means that warm moist air can get in, find a cool surface, and condense. Result: The wall gets wet, mold and mildew begin to grow. u Moisture can be carried by the flow of air into or out of the home through holes and cracks in the building envelope. This airflow is caused by a variety of forces including stack effect, the wind, and mechanical systems. u By building a tight envelope and controlling mechanical pressures, we can reduce moisture flow through a building.
11 Preventing heat, moisture & air flow through the building envelope u Start with air-tight framing u Testing at insulation stage (we found biggest leaks due to framing) u WRB barrier, taped top, bottom, edges u Stopping wind pressure from producing air infiltration u Interior barrier methods u Poly/air-tight drywall, smart vapor retarders (vapor retarders whose vapor permeability changes based on the humidity conditions) u Connecting the interior and exterior barriers u Sealed to framing for complete air block u Under slab control of moisture & radon u Poly film, polystyrene board
12 Start with air-tight framing Caulking the framing Caulking the framing
13 Rim joist areas These areas need sealing
14 Sealing the gaps Penetrations such as electrical boxes Bottom plate Foundation to wood connections
16 Follow up after sheetrock installation, attic & walls, etc.
17 Preventing heat & moisture flow through the foundation system u u u u u u u Build foundation like a boat hull underwater Capillary break between footing & foundation wall (radon control) Connecting the capillary break to under slab radon control Insulating under the slab (new energy code) Use of ICF Capping the foundation top with waterproof membrane Connection between foundation and framing
18 Under Slab Poly & Foam Board Poly from under ICF wall Sealing around plumbing
19 Connection between foundation wall & framing
20 Connection between foundation wall & framing WRB sealed behind foundation protection
21 Basics at design stage of house u Planning for minimal ductwork u Keeping ducts inside the thermal envelope u Pass-through instead of ducted returns when possible to minimize ducts u Simplified design of home u OVE framing u Line up floor trusses, wall studs, roof trusses (24: o.c.) u Reduce thermal transfer
22 Central Returns w/pass throughs
23 Pass-throughs, returns
24 Material options (insulation, windows, mechanicals, etc.