A growing glossary of words and terms, in alphabetical order, related to sustainable design and construction – just in case you’re not familiar with them. 

Building Envelope:  the physical element that separates the conditioned (heated and cooled) environment of a building from the unconditioned. An airtight and very heavily insulated envelope is essential for Net Zero/Net Positive Passive houses.

Carbon Footprint:  the combined amount of greenhouse gases we produce to support our activities, expressed in terms of carbon dioxide (CO2). Heating our homes with fossil fuels, and even electricity generates CO2. The production of the foods we eat emits quantities of CO2. The gas we use in our cars is an obvious culprit. When we add up all the CO2 emissions we generate through our activities over a certain period of time, that’s our Carbon Footprint.

CERV:  Conditioning Energy Recovery Ventilator, which includes an air-source heat pump. It’s a great improvement on previous Energy Recovery Ventilators, or ERVs, and a wonderful means for reaching Net Zero/Net Positive. Both ERVs and CERVs bring fresh air into a home or building, but the CERV can dehumidify, preheat, and pre-cool that air before it comes in. CERVs also monitor humidity, VOCs, and CO2, and adjusts the amount of fresh air needed.

CRI: Color Rendering Index. It measures an artificial light source’s ability to reveal colors as accurately as a natural light source (sunshine). In our homes, for example, light bulbs with a high CRI let colors pop, reveal textures, and give finishes depth and luster. The higher an artificial light’s CRI, the better it is at portraying colors accurately.

Geothermal heating and cooling: A brilliant, eco-friendly HVAC system that takes advantage of the stable temperature deep underground to keep homes and buildings comfortable year-round with remarkably high efficiency. Geothermal uses a piping system called a “loop.” Water circulates in the loop to exchange heat between your home, the ground source heat pump, and the stable temperature of the earth. Another benefit: It’s completely silent.

Ghost Loads: The electrical power consumed by electronic devices and electrical appliances while they’re supposedly switched off or in standby mode. Those tiny lights are eating up energy bit by bit, contributing to our Carbon Footprints.

Gray Water:  used water from baths, sinks, and washing machines that you would normally send down the drain. Most gray water can be broken down and safely reused to irrigate gardens and lawns.

High-Performance Building: According to the Energy Independence and Security Act of 2007, Section 914, Building Standards, a high-performance building “integrates and optimizes on a life cycle basis all major high-performance attributes, including energy conservation, environment, safety, security, durability, accessibility, cost-benefit, productivity, sustainability, functionality, and operational considerations.” Net Zero/Net Positive houses are clearly high-performance houses.

HERS: Home Energy Rating System. HERS is based on an analysis of a home’s energy efficiency as laid out in the HERS Index, the nationally recognized scoring system for measuring a home’s energy performance. Based on the results, the house receives a score. The higher the score, the poorer the performance. Sadly, the average American home has a very poor HERS rating of 100. (FYI: Our Serdar house received a HERS rating of 13. The independent rating company told us that it was the lowest/best rating they’d ever seen!)

Micropolis® Houses: The collection of modern, sustainable, customizable, tiny house plans designed by Arielle Schechter, AIA, and available for purchase. For all the background, details, floorplans, and rendering, drop by http://www.acsarchitect.com/micropolis-houses-plan-index.

Net Positive house:  A Net Positive house is so air-tight, insulated, and in every other way energy efficient that it produces more renewable energy that it uses. Net Positive houses combine innovative design and state-of-the-art building systems with energy efficiency (see Passive House below) and solar arrays. As a result, the homeowner can use that extra energy for other purposes, such as powering an electric car.

Net Zero house:  A Net Zero house is a grid-tied house that is so air-tight, insulated, and energy efficient that it generates just as much renewable energy as it consumes over a year. Innovative design, state-of-the-art building systems, energy efficiency (see Passive House below), and photovoltaics are also key to achieving Net Zero. The result: a net zero energy bill and a carbon-free home.

Passive House: Simply explained, the design principles and rigorous standards for a Passive house focus on lowering energy consumption during day-to-day living to create an ultra-energy efficient, comfortable home. If you really want to know why and how, visit the Passive House Institute of the US website. Otherwise, suffice it to say that Passive house design is the stepping stone to achieving Net Zero.

PHIUS Certification: accreditation from the Passive House Institute of the US (PHIUS) indicating that a house is truly Passive. Certification combines design verification protocol with stringent quality assurance and quality control programs performed on site by specialized PHIUS+ raters.

Photovoltaics: the science behind our ability to harness solar energy and convert it into electricity. A photovoltaic system, also referred to as a PV system, uses solar panels to capture sunlight’s photons. If you’d like to learn more about the components of a PV system and how they work together, click here.

SIPs: Structural Insulated Panels. The SIP Association explains: “SIPs are a high-performance building system for residential and light commercial construction. The panels consist of an insulating foam core sandwiched between two structural facings” that are “manufactured under factory-controlled conditions and can be fabricated to fit nearly any building design. The result is a building system that is extremely strong, energy efficient, and cost-effective.”

Stormwater Runoff:  When rain falls of roads, parking lots, driveways, and other solidly paved surfaces, it can’t be absorbed back into the earth immediately. Instead, it runs across the paved surface, gathering all the oils, trash,  and other pollutants there and taking them down into a town’s or city’s drainage system and natural streams. Stormwater runoff is the primary source of pollution of the nation’s natural stream systems.

Sustainable Design: In architecture, sustainable design, often referred to as “green” design, is the goal when we, as architects, minimize our buildings’ negative environmental impact by reducing their use of non-renewable natural resources, minimizing waste, and creating healthy environments for their occupants. Sustainable design …

  • Optimizes the site’s potential and disturbs the land as little as possible
  • Minimizes the use of non-renewable energy by maximizing such assets as natural lighting and ventilation, etc. The use of locally available materials falls under this category for several reasons, including the fact that they don’t have to be shipped far so they use less energy in transit. There are many, many ways to avoid using non-renewable energy.
  • Uses eco-friendly, sustainable products
  • Protects and conserves water by employing, for example, rainwater collection cisterns for landscape irrigation and porous pavers to let rainwater soak into the earth quickly, thereby avoiding stormwater runoff.
  • Enhances the quality of the indoor environment by, for example, avoiding pants, stains, and upholstery with VOCs
  • Optimizes operational and maintenance practice


VOCs: Volatile Organic Compounds. VOCs are emitted as gases from a variety of sources, including but not limited to paints, glues, stains, and varnishes; cleaning supplies and improper combinations of cleaning supplies; and chemically treated carpets, rugs, upholstery, and certain lumber used for outdoor decking. VOCs are very harmful to our health. To read the EPA’s recommendations for reducing VOCs in your home, click here.



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