The Anatomy of a High Performance Home
A modern, high-performance home provides you with energy-efficiency, safety, and a high-level of indoor environment quality (IEQ) for your family's comfort. It's also a smart financial investment. You will save money with lower energy bills and maintenance expenses. You can also expect to sell your green-certified home for 3.6%1 more per square foot than a non-certified house.
A high-performance house design requires a whole-building approach that treats the house as a single energy system where each part improves or degrades the whole house's performance. The integrated design approach will ensure a durable and sustainable high-performance home with superb IEQ and long-term financial benefits. Vital design features of a high-performance house include passive strategies, an airtight and moisture-resistant building envelope, and energy-efficient electrical, mechanical, and plumbing components.
1. Passive Design Strategies for Your High-Performance Home
Passive design strategies utilize a simple and relatively low-cost approach to reducing your energy needs and maintaining a comfortable temperature in your home. A Canadian study found with passive designs can contribute up to 74% of a home's heating requirements. Passive strategies include solar orientation, shading, and the use of ventilated cavity facades. The passive design will lessen your need for mechanical heating or cooling, saving you energy, and money.
Solar Orientation of Your Home
Facing the long axis of your house south will take advantage of the seasonal changes in the Sun's path, optimizing the heat loads imparted on the interior spaces through the walls and windows of your home. Your high-performance home's proper solar orientation can reduce your need for mechanical heating and cooling, saving between 10% and 40% on energy costs.
Shade Your Home
Shading your home lowers solar heat gain, saves energy, and improves your families' comfort. Effective shading, like awnings, canopies, and porches, reduces unwanted solar heat gain in the summer, but maximizes the Sun’s warmth in the winter. Window awnings can reduce solar heat gain in the summer by 65% on south-facing windows and by 77% on west-facing windows. Shading your house with trees and other landscaping can also reduce heating and cooling consumption by up to 25%.
2. A Tight-Building Envelope
The building envelope of your house includes the walls, windows, doors, foundation, and roof. A high-performance, energy-efficient, comfortable, and resilient home consists of a tight building envelope that minimizes the flow of air, moisture, and heat. When designing a tight building envelope, you must apply continuous insulation, mass walls, airtightness, and energy-efficient windows and doors.
Continuous Insulation (CI)
For a high-performance house, you need to wrap the building’s envelope, including all structural members, exposed slab edge, walls, foundation, and roof, with a layer of continuous insulation (CI). CI will increase the effective R-value and eliminate thermal bridging. Continuous insulation is a crucial and mandatory element of a high-performance house.
Energy-Efficient and Durable Mass Walls
Insulated concrete form (ICF) mass walls will add both energy-efficiency and durability to your house. Energy-efficient mass walls absorb thermal energy during the day and release energy after sunset in order to minimize indoor temperature swings throughout the day, resulting in lower energy use to heat and cool the home relative to light-framed walls. Mass walls last longer and require less maintenance than light-frame walls. You can expect an energy savings of 30-40% with ICF mass walls over wood-framed walls.
Energy-Efficient Below-Grade Walls
A high-performance home's below-grade walls should minimize thermal bridging and moisture infiltration into the foundation or basement walls through durability and moisture- and air-resistance. It is estimated that 15% of heat loss in a home occurs through the basement walls and the foundation footings. Therefore, a high-performance house's foundation or basement walls should include a moisture-resistant barrier and an insulative R-value of at least 20 to 30.
Airtight and Moisture-Resistant Barrier
The design of a high-performing house should reduce outside air infiltration into your home. Air infiltration accounts for 25-40% of the energy losses in a home. It can also significantly impact your family's comfort and the lifespan of the house. For an airtight, high-performance home, you should apply a continuous air and moisture barrier, have an unventilated attic, and utilize Energy-Star windows and doors, and air seal all transitions.
A continuous air and moisture barrier system applied to the wall, foundation, and roof minimizes air and moisture infiltration inside a house. You can save up to 36 percent on energy costs by using an air barrier.
A high-performance home benefits significantly from an unventilated attic, with energy savings as high as 20%. Unventilated attics seal the space by applying a thermal and air envelope to the roof, instead of the ceiling, which will lessen the heat load on mechanical systems located in the attic. You will also find it easier to control air infiltration from the recessed lights and other penetration through the ceiling into the living spaces of your home.
ENERGY STAR Windows
Energy-efficient ENERGY STAR windows can lower your household energy bills by 7-15 percent. They will also reduce greenhouse gas emissions from power plants and shrink your house's carbon footprint.
- Low-E (emissivity) coatings on your windows reduce infrared and ultraviolet lights passing through the glass but do not impact the amount of transmitted visible light.
- Solar Heat Gain Coefficient (SHGC) represents the fraction (0 to 1) of incident solar radiation traveling through your window. The right SHGC for your windows depends on your climate zone: in cold regions, select windows with a higher SHGC, and in warmer climates, choose windows with lower SHGCs that transmit less solar heat.
- Thermally broken window systems provide a conductive material that separates the glazing's external and internal metal frames and stops conductive thermal energy loss. While it may seem insignificant, these sources of thermal bridging can tremendously impact your home's energy performance.
Insulated Exterior Doors
For the doors of a high-performance home, you typically can choose either insulated steel (R-value of 5) or fiberglass doors (R-value of 6). Insulated exterior doors will help make your home warm and comfortable.
Air Seal All Transitions
A high-performance home must include a complete and uninterrupted air-barrier system. By sealing all barrier membranes, penetrations and air leaks throughout your home, focusing around the windows, doors, attic space, and foundation, you can achieve a 25% reduction in total air infiltration.
3. Energy-Efficient Electrical, Mechanical, and Plumbing
In 2019, lighting represented 5% of the total residential electricity consumption in the U.S. Therefore for a high-performance home, you should use energy-efficient light-emitting diodes (LEDs) which are bulbs that use 75% less energy and last up to 25 times longer than incandescent lighting. LED bulbs utilize semiconductor diodes that change electricity into light. While slightly more expensive to purchase, LED lights more than pay for themselves in just a few years.
Variable-Speed Heat Pump or VRF “Ductless” System
You can increase your home's energy efficiency, air quality, and comfort with a variable- speed heat pump or variable refrigerant flow (VRF) ductless system. You can save about 18% on primary energy compared to a single speed-heat pump unit.
The VRF system saves energy by operating at the precise speed and only heating and cooling your home's needed spaces. It also eliminates duct leakage and duct heat. A VRF ductless system improves air quality because it localizes air filtration to each room and stops contaminants' from entering a home through leaky air ducts. A VRF ductless system also allows for exact temperature control, providing greater comfort to your family than a central HVAC system.
Adding supplemental dehumidification to your mechanical ventilation system can better help you manage indoor humidity than just an HVAC system — this is particularly vital if you live in a hot and humid climate. ENERGY STAR® certified dehumidifiers are 15 percent more energy-efficient than conventional models.
An airtight and energy-efficient home requires mechanical ventilation to remove pollutants, allergens, and mold producing moisture. A high-performance home needs a mechanical ventilation system to achieve the mandated ventilation rate set by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE).
You can select from several mechanical ventilation systems, based on your local climate and your home’s heating and cooling system: supply ventilation systems for hot and mixed climates, exhaust ventilation systems for cold climates, and balanced ventilation for all climates.
The energy recovery ventilation (ERV) version of the balanced ventilation systems provides the most energy savings. An ERV system transfers heat energy exiting a house to the cold air entering the house. The transfer occurs within a heat exchanger, minimizing energy loss in your home.
Also, along with one of these systems, you should install spot ventilation fans in your kitchens, baths, and laundry room to remove the concentrated moisture and odors that can occur in these rooms.
Heat Pump Water Heater
Heat pump water heaters use heat from the air to heat the water in a water tank. Energy-efficient heat pump water heaters can save about $350 per year on your household's electric bills over a standard electric water heater.
Why Fox Blocks Benefit the Anatomy of a High-Performance Home
The anatomy of your high-performance home, including both methods and materials, will control your energy bills and keep your family safe and healthy. For your high-performance home above-and below-grade wall system, Fox Blocks insulated concrete forms (ICFs) can significantly help achieve airtightness, energy-efficiency, durability, and excellent IEQ — the principal goals of a high-performance home.