At Homoly Construction, we have been exploring High Performance initiatives long before they became popular.
Company president and owner Andrew Homoly received an Environmental Emphasis in Civil Engineering at the University of Illinois, whose Civil Engineering program is consistently ranked #1 in the nation. Andy is one of a select few designated as a LEED AP (Leadership in Energy and Environmental Design Accredited Professional), and Master CGP (Certified Green Professional) through the NAHB (National Association of Home Builders). With these certifications, Andrew is on the cutting edge of High Performance Building techniques for Residential construction.
While early Green initiatives were costly, inefficently designed, and generally generated low returns on investment, recent advances have made Green techniques much more affordable and effective. Green Building is now Better Building.
The five core components of the Homoly High Performance Building Program are:
- Site Selection and Design
- Resource Efficiency
- Energy Efficiency
- Water Efficiency
- Indoor Air Quality
Homoly Construction has recently completed building two of the high performance homes in Kansas City: the Williams-York Residence and the Homoly Residence, pictured below. Both homes have achieved "net-zero" and at times supply electricity to the power grid. In contrast to the modern architecture of the Williams-York Residence, the Homoly Residence showcases a more traditional style. high performance building techniques have come a long way in providing options for all design-styles.
Site Selection and Design
- Orientation - the front or back of the home should face south or within 30 degrees of south for passive solar heating and cooling.
- A proper Green design must consider the temperature zone of the location and design accordingly. A Green home in Minnesota will be designed very differently than a Green home in Florida. The Midwest is toughest location since it has high heating and high cooling loads.
- Large overhangs and proper window placement for solar heating in the winter (when the sun is low on the horizon) and solar shading in the summer (when the sun is high on the horizon).
- Orient the home to take advantage of prevailing breezes in the spring, summer, and fall.
Resource Efficiency and Durability
- "Tear downs" should be "deconstructed" to recycle as many materials as possible. With tax credits, this can often be done at no cost or cost savings.
- Check the "life cycle analysis" of all material used. A renewable Green material like bamboo may not be Green if it has to be shipped from the other side of the world. Oak flooring from a mill less than an hour away may be a better choice.
- Look for FSC certified wood. This is certified to be from a renewable forest.
- All flashing must be installed "shingle style" to maximize water shed.
- Create capillary breaks in masonry and wood.
- All waste materials (non-recyclable) should be separated in dumpsters by type and removed by a waste hauler to an appropriate facility.
- In almost all cases, the additional cost for energy efficient systems (such as geothermal, SIPS, and conditioned attics) will create a rise in the mortgage payment that is less than the utility bill savings created by those systems. In other words, these green features can save monthly cash flow from the very first month of operation.
- Create a tight thermal envelope using advanced insulation techniques such as SIPS or foam insulation (open or closed cell).
- Conditioned "sealed attics", especially when ductwork runs through the attic. This technique provides a superior air seal in the attic portion of the thermal envelope since penetrations through the ceiling are now within the envelope. HVAC units and ductwork will gain significant efficiency in the controlled space, especially during the heat of the summer or cold of the winter. Storage areas and living areas within the attic space are now more comfortable.
- If a high roof pitch or size of the roof makes a sealed attic cost prohibitive, "box in" the HVAC systems and insulate these chases.
- Geothermal HVAC systems. Earth exchange lines may be drilled vertically, horizontally, and potentially around the foundation of the home or in nearby ponds.
- The installation of a radiant barrier on the backside of OSB roof sheathing will deflect a large percentage of the sun's radiant energy and keep the attic cooler.
- For a radiant barrier to work properly, an air gap must be present underneath the radiant barrier surface. This can be accomplished with baffle channels between the sheathing and foam insulation or traditional ceiling insulation.
- Energy Star appliances.
- Compact fluorescent light bulbs or LED's.
- Without an air barrier, air will flow through regular insulation and negate the R Value of the insulation.
- A standard framed wall is made up of 25% wood (studs). This can be visualized by imagining all of the studs in a normal wall have been placed right next to each other on one end of the wall. Wood has an R Value of 3. Therefore, 25% of every wall has an R Value of 3 due to thermal bridging.
- The installation of 1" to 2" of insulating board on the outside of the exterior walls to eliminate the thermal bridging effect of the studs in a wall.
- Structural Insulated Panels (SIPS) solve several key issues, including the thermal bridging problem of wood studs.
- Sealing all ductwork.
- Not using flex duct (not efficient and easy to install incorrectly - pinch areas are common).
- Foundation wall insulation, preferably on the outside. This should extend all the way up to the rim joist. An 8" concrete wall has an R value of 2. Up to 22% of the heat loss in a home can come through the basement walls above the grade level.
- Minimize can lights in the upper ceiling of the home to avoid penetrations in the thermal envelope. If they are necessary, "box" them in at the attic location to properly insulate that area.
- Minimize the number of outlets and light switches in the exterior walls to minimize penetrations in the thermal envelope.
- Solar systems - these can include electricity generation, hot water heating, and direct heated air circulation systems.
- Wind generation - Residential "kits" are now available for single home wind power generation. Rotor styles have now brought the cost down from the generator models.
- A "control panel" website can be set up to continuously monitor the energy usage (or production) of a home. Studies have found that energy usage decreases dramatically when occupants can easily track the actual energy used on a real time basis.
- To save costs on spray foam, use 1" to 2" in wall cavity for the air barrier and then use traditional insulation in the rest of the cavity.
- Low e windows are helpful, but not a substitute for proper orientation, overhangs, and window placement.
- A "Net Zero" home uses no net electricity over the course of a year. Any electricity used during cloudy low wind conditions is offset by extra electricity generated during sunny high wind conditions. The excess electricity is sent back to the grid and sold to the utility company. Net Zero homes are possible with today's technology.
- Drywall can be used as an airtight seal when properly installed and caulked.
- Foam under switch plates.
- "Super" windows are now available with an R Value of 11. These are triple pane windows with multiple low e coatings or window sections with layers of a special heat film.
- High windows or vents in a cupola type area take advantage of the stack effect and draw cooler air in through the lower windows or vents. This mimics the design of our capital buildings that used the "dome" as a method to air condition the buildings.
- Minimize tall ceilings.
- In an existing home, insulation can be applied to the inside of the basement wall to gain the insulating effect. However, the thermal massing properties of the concrete wall are negated with insulation on the inside of the basement.
- "Over framing" with extra studs will add to the thermal bridging effect. This is very common since framers tend to think they are helping the construction of the home by adding additional studs around doors, windows, etc.
- "Advanced" framing techniques will minimize studs and the thermal bridging effect.
- Insulated Concrete Forms (ICF's) for foundations and potentially the main exterior walls.
- Proper tree species placement can assist passive solar heating / cooling by blocking the sun in the summer and allowing the sun to pass through (when the leaves fall off) in the winter.
- Check completed homes with an infrared camera for heat loss.
- Check completed homes with a blower door test for duct leakage.
- Insulating hot water lines for energy loss prevention.
- Dark roofs will absorb heat. Use lighter colored roofing when possible.
- Solar water heating systems can be used for radiant heating and domestic water production.
- Solar systems of today have made the evolutionary step to be cost effective, especially with the current federal subsidy of 30% of the solar cost.
- Solar, wind, and geothermal systems receive a 30% tax credit until 2016.
- Sealing the sill plate to the top of the foundation wall with caulk.
- An air barrier (such as a piece of OSB) behind tubs, shower units, and soffits, in addition to the insulation to stop air infiltration.
- A Green home is like a high performance car, it will require more operator skill to obtain all the benefits.
- Low volume plumbing fixtures. This includes 1.0 gallon pressure assisted toilets, dual flush toilets, low volume shower heads, low volume faucets, and waterless urinals.
- Capture rainwater in a storage tank for irrigation or to flush the toilets.
- Properly landscape for water conservation with the correct species of plants and grasses.
- Proper placement of the water heaters can negate the need for a circulating pump or running the water to get hot water.
- A thicker layer of top soil will require less watering in the hot summer months.
- Use underground drip irrigation in lieu of traditional sprinkler systems.
Indoor Air Quality
- With a "tight" home, you must use an air exchanger for indoor air quality. An HRV or ERV will use the air exiting the home to heat up or cool down the air entering the system. The ERV will also exchange the humidity control. These systems can be tied into the existing bath fan systems.
- Properly sized HVAC systems. Most systems are oversized to make sure they cool in the summer, but this can lead to cooling too quickly and not enough time to remove the humidity from the air. A properly sized system will also be smaller and cost less money.
- Air filters should have a high Merv rating to get the best possible results.
- Installation of the vapor barrier on the side of the wall (exterior or interior) where the moisture is coming from. Moisture will always drive from wet to dryer air. If the vapor barrier is on the wrong side, water could condensate on the inside of the wall and cause mold. In Kansas City, this is both sides depending upon the season.
- Closed cell foam insulation acts as a vapor barrier on both sides of a wall.
- Front loading washing machines for energy efficiency and less humidity in the home.
- Insulate cold water lines to reduce condensation in the walls.
- Slightly pressurize the home for better indoor air quality.
- Use Green label flooring (less or no VOC's)
- Use Green paint (less or no VOC's).
- Indoor pollutants are exacerbated at high and low levels of humidity. Humidity levels must be kept between 35% and 50% relative humidity to minimize pollutants.
- Install timers on exhaust fans in bathrooms and the kitchen.
- Prepare ahead of time for a radon system while constructing the home with sealed concrete floors and conduits in the walls to the attic.
- Schedule wood deliveries on a "just in time" basis to avoid unnecessary moisture in the wood.
- Garages should be detached if possible to avoid the bad air that gets pulled into the home.
- If the garage cannot be detached, use a fan or other system to keep the garage air from going into the home.
- Avoid chemical treatments for termites and other pests.
- Air out carpeting 2 days before installation.
- Seal off the sump pump and caulk the slab joint to foundation wall to keep earth gasses from entering the home (especially radon).