Your Energy Envelope
Your home’s ‘energy envelope' protects you from the elements. It includes the foundation, walls, windows, doors, roof, insulation, and air sealing. Although the envelope determines your home’s performance capabilities, it usually takes second place to the exciting part of building – Design! If you want to jump ahead to Design, click here, but come back to learn how critical the energy envelope is to your future comfort and cost savings.
High performance energy envelopes are NOT common in homes today – but Stitt does not build common homes. Our clients want nothing short of comfort, beauty and low utility bills. In other words, they want uncommonly high performance. The energy envelope of a typical Stitt home enables it to consistently perform up to 30% better than the ENERGY STAR® standard and up to 70% better than homes built to meet the International Energy Conservation Code (IECC).
A Stitt Energy Systems’ foundation begins with footings and slabs that meet or exceed local code requirements. It also complies with Energy Star® 3.0 guidelines for moisture control. We assemble Insulated Concrete Forms (ICFs), add supports and rebar, and pour concrete in to form the foundation walls. A six inch ICF wall assembly provides an R-value of 22.
Because of its insulative properties, ICF construction eliminates thermal bridging. Thermal bridging occurs when components like un-insulated foundations and wall and roof framing create a ‘bridge’ between the inside and outside of your home through which heat easily escapes. To eliminate any chance of moisture buildup, mold, and the odors that come with it, we apply a material drainage plane on the exterior of the ICFs and place drainage tiles around the foundation.
Stitt offers several wall construction options for your new home. We select the best option for your home based on environment, location, and your preferences. If your home needs to withstand high winds or ground tremors, we will recommend a stronger option than if you live in a moderate climate with stable ground. If you need sound
attenuation or plan to hang a significant amount of wall art, those needs will also affect the wall construction we recommend for your home.
All exterior walls on a Stitt home are covered with a continuous drainage plane and flashed at the bottom to prevent moisture infiltration. Weep holes are provided for masonry veneers so that any water or condensation that forms behind the brick or other veneer can escape.
Interior walls in bathrooms, kitchens and other areas where water is used are treated or covered with water resistant or water proofing materials.
Windows and Doors
We recommend Low E glass, Argon gas-filled windows to make the most of passive solar design. Low-E windows allow short-wave energy from the sun to enter and heat your home in the winter. At the same time, they prevent most of the heat inside your home from escaping out through the glass. Argon gas improves window efficiency by reducing the conduction of heat through the space between the two panes of glass.
For exterior doors, we recommend insulated frames with fiberglass exteriors and adjustable thresholds. They resist warping and cracks to give your home years of energy efficient performance with very low maintenance. Regardless of style, Stitt Energy Systems requires that all windows and doors be installed using high quality flashings around each opening to prevent air and water infiltration.
Your roof faces stress and damage every day – blistering heat, freezing rain, hail, and wind are just the beginning. Stitt ensures that all valleys and roof deck penetrations are sealed with an appropriate waterproofing membrane. We also use step and kick-out flashings at all roof-wall intersections to prevent water from seeping into your walls. Raised-heel trusses are standard on Stitt homes because they enable us to increase the amount of insulation where your roof and wall intersect.
To prevent temperature extremes from reaching your attic, Stitt Energy Systems installs a proprietary radiant barrier known as the Ice House Roof® below your roof decking and between the rafters. Combined with continuous soffit and ridge venting, the Ice House Roof® creates natural convection to carry heat away from your attic before it is absorbed. This eliminates extreme attic temperature variations and the need for attic fans and gable vents. It also prevents the formation of ice dams.
Installing light colored roofing, regardless of material, can decrease heat build up in attics, but using the Ice House® Roof allows you to choose a dark roof if you want while still achieving a high level of energy efficiency.
Insulation and Air Sealing
The final step in completing your new home’s energy envelope is to insulate and air seal all exterior walls. The type of wall system used in your home will determine which insulation and air sealing products are best. Air sealing options range from exterior house wraps and peel-and-stick membranes to interior spray foam. Insulation options include spray foam and insulated structural sheathing.
Stitt Energy Systems recommends lightweight, semi-rigid, soy-based spray foam be applied to your exterior walls and in your attic. This both insulates and air seals your home’s energy envelope. Unlike traditional insulating materials, this soy-based spray is less prone to gaps, compression, and moisture, which reduce R-value. Because of the way we apply it, this spray insulation also eliminates most thermal bridging. Our designer will recommend your best-value option after considering both cost and performance.
Even before Energy Star® required that homes be tested for efficiency, Stitt Energy Systems used a blower door unit to test our homes for air leaks. Under today’s Energy Star® guidelines, our homes are inspected and tested multiple times during construction.
A home energy rater, certified by the Residential Energy Services Network (RESNET), conducts a walk-through inspection after insulation is installed to ensure it is installed properly and is installed in such hard-to-spot and easy-to-forget locations as walls behind tub and/or shower enclosures, behind fireplaces, in attic knee walls, and in skylight shaft walls. The rater also checks for air sealing and thermal bridging prevention.
At the same time the rater is conducting the interim inspection, Stitt Energy Systems personnel conduct a blower door test to check for air leaks. If any are found, we correct them before drywall or any other interior wall finish is installed. At the end of construction, the home energy rater conducts a full inspection of the house. This includes testing the HVAC system, the
efficiency of appliances and lights, and a full blower door test to establish the energy performance and quality standards of the house.
RESNET has created a home Index which provides a scale to rate homes on insulation, ventilation, tightness, heating and cooling systems, water heater efficiency and solar gain. The lower a home’s score on the Index, the more efficient it is. You can learn more about it here.