Common green terms to understand in ZNE home building

green path

Love the idea of net zero energy home building but not sure about the difference between PV or solar thermal? Below is a list of frequent terms you might encounter while learning about this building style, and the science behind it. To give the definitions more meaning, we recommend that you look through the rest of the resources listed under Learn Zero to deepen your understanding.

Advanced Framing Techniques minimize the amount of lumber needed to frame a structure and increases the amount insulation, which improves the whole-wall thermal resistance or R-value.

Bamboo flooring is a product of fast-growing trees and is more sustainable and durable than traditional wood floors.

Building envelope is the separation (foundation, roof, walls, doors, and windows) between the interior and exterior environments of a building.

Composite lumber is extruded lumber made primarily from recycled wood and recycled plastic.

Deconstruction is the reverse of home construction where structural materials are salvaged and can be reused at the end of a building’s useful life.

Demolition recycling describes using materials from deconstructed homes on new construction projects, diverting as much as possible from landfills.

Drip irrigation minimizes the use of water and fertilizer by allowing water to drip slowly to the roots of plants.

Earthtubes are non-electric heating, passive geothermal solar heating and low-tech solar cooling systems designed to preheat the fresh air supply to the ventilation system during the cold season.

ENERGY STAR is the name of a federal labeling program that identifies energy-efficient appliances.

Energy-recovery ventilator (ERV) is a mechanical element of a home designed to provide continuous or timed ventilation throughout a home and recover the heat carried in the exhausted stale air.

Engineered lumber is lumber that has been engineered for efficiency and is composed of fast-growing trees.

Evaporative cooler is a mechanical element to a home that cools and humidifies outdoor air by allowing it to pass through water-soaked pads; uses about 75% less energy than central air conditioners.

Fiber-cement exterior siding offers a long lasting alternative to typical exterior wall cladding.

Foam or blown-in insulation is made of polyurethane foam that is sprayed into a cavity, then expands and hardens to fill the available space. It is far more effective than conventional batting insulation as it fully seals and prevents air leakage.

Forest Stewardship Council (FSC)-certified is a program designed to verify whether lumber is taken from sustainable and healthy forests. FSC-certified flooring and cabinetry is a great choice for the planet!

Geo-exchange or ground-source heat pumps describe a system of underground piping that utilizes the constant temperature of the earth to heat air in winter or cool air in summer, reducing energy loads required to achieve a comfortable indoor temperature.

Green Points is a City of Boulder mandatory residential green-building program that requires inclusion of a variety of sustainable building components and awards points for sustainable building practices.

Grid-tied system is a PV system connected to the power grid that allows you to sell excess electricity back to the utility.

Heat mirror glazing is a type of window glass that enables higher light transmission and lower reflectivity to be achieved in windows while maintaining the required level of thermal insulation, compared with conventional low-e insulating glass.

Heat-recovery ventilation (HRV) is a mechanical element of a home designed to provide continuous or timed ventilation throughout a home and recover the heat carried in the exhausted stale air.

Home Energy Rating System (HERS) Index is a scoring system between 0 and 100; the lower the score, the more energy efficient the home; a zero net energy or net-zero energy home scores a HERS Index of 0.

High-performance windows have new frame materials and designs; low-E and/or solar control coatings; low conductance gas fills; insulating spacer between glazings.

High-efficiency boiler/furnaces are major mechanical systems of a home that provide heat and achieve 90%–97% efficiency in the energy in its fuel over the course of a typical year.

Hydronic forced air is a mechanical system of a home that combines hot water heating with forced air delivery.

Hydro-zoning is a landscape practice that groups plants with similar water requirements together in an effort to conserve water.

kWh is an acronym for kilowatt hour, a unit of energy equal to 1000 watt hours and is most commonly known as a billing unit for energy delivered by electric utilities.

Leadership in Environmental and Energy Design (LEED) is a third-party certification program and the nationally accepted benchmark for the design, construction, and operation of high-performance green buildings.

Lifetime Cost describes the upfront cost of a renewable energy system improvement plus the total predicted energy costs for a specific time period.

Low-E describes low-emissive glass is coated with a metallic oxide layer that improves thermal performance.

Low-flow fixtures include toilets, showerheads, and faucets that use low amounts of water while still maintaining adequate water pressure; washing machines and dishwashers with high water conservation standards.

Modified Internal Rate of Return (MIRR) can be used to compare an investment in energy savings to a financial investment such as a savings account or money market.

Modified Payback is a method that incorporates an estimate of increasing energy prices, discount rates, and other factors to determine a more realistic value of the savings.

Open-cell foam is low-density, non-toxic spray foam insulation made from castor oil that can be used in wall, floor, and roof assemblies. It has a high R-value that it won’t lose over time, provides acoustic insulation, and will stick to many construction materials, allowing less use of petroleum-based products.

Passive solar describes a design approach in which solar energy is brought into a home through south-facing windows and is absorbed and then slowly released by thermal mass to heat a building.

Payback is the number of years it takes for the energy savings from an improvement to equal the upfront cost.

Pervious pavement is designed to allow percolation or infiltration of storm water through the surface into the soil below where the water is naturally filtered and pollutants are removed.

Photovoltaic (PV) cells are electricity-creating devices made of semiconductor materials that convert light into DC voltage, connected to form PV modules (or solar panels). Modules are combined and connected to form PV arrays. A PV system consists of PV arrays, electrical connections, mounting hardware, power-conditioning equipment, and batteries (if not grid-tied). A grid-tied system is connected to the power grid, whereas a battery-backup system stores electricity generated in large batteries.

Programmable thermostats allow you to automatically adjust your home’s temperature to ensure comfort during the day and energy-savings when you’re sleeping or away.

Radiant floor heat distributes heat via hot water pumped through tubes under the floor.

Return On Investment (ROI) is a measure of cash produced by an upfront investment.

Rigid board/foam are rigid panels of insulation that provide good thermal resistance and often add structural strength to the home.

R-value is the measure of a material’s resistance to heat flow. The higher the R-value, the more it insulates.

Savings to Investment Ratio (SIR) takes the total energy savings over the lifetime of the improvement (present value) divided by the upfront cost of the investment. This calculation may or may not include increases in energy prices or inflation rates.

Seasonal Energy Efficiency Ratio (SEER) measures the efficiency for air conditioners (A/C); the current minimum is 13 for central A/C and 12 or more for ENERGY STAR models.

Simple Payback is a calculation of Cost ÷ Savings = Payback (in years)

Structurally Insulated Panels (SIPs) are structural panels that use an insulating material sandwiched between two sheets of boards to create roofs and walls.

Smart Irrigation Controller is a clock that automatically adjusts landscaping irrigation run-times in response to environmental changes. Smart controllers reduce outdoor water use by an average of 15 to 30 percent.

Solar thermal collectors are made of flat plate or evacuated glass tubes that absorb direct heat from the sun and use it to provide domestic hot water and/or space heating.

Tankless water heaters flash-heat water only when it is needed, saving both water and energy. In contrast, traditional hot water heaters must keep a water storage tank consistently heated.

Xeriscape or low-water landscaping is a method of landscaping that utilizes plants with low-water needs.

Zoned heating allows heat to be delivered to individual areas of the home when needed.

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