Category Archives: jargon

Blots, or Blotting

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by jargon, terms • Tags: , , , , , , , , , , , ,

(Image credit: StructureHub)

I started hearing about blots and blotting late last year, first via a couple posts I found on Shrinking Cities (here and here) and then most recently via a story on NPR. Both sources feature stories about the de-densifying city of Detroit. Interboro claims credit for coining the term “blotting” about eight years ago.

According to Shrinking Cities, “the use of ‘blots’, or ‘side lot expansions’, is a technique that gives homeowners with vacant land adjacent to their home the opportunity to purchase that property as an expansion to their own for a nominal cost.”

The NPR story cites a startling statistic – in Detroit, it’s estimated that up to 40 square miles of land sits vacant.To give a sense of scale,the entire city of San Francisco is about 47 square miles. So both formally and informally, Detroit is encouraging its residents to buy or just sort of annex adjacent properties in order to take care of the properties and stabilize neighborhoods.

Part of our series making sense of eco-lingo and technical terms.
For more, check out our Jargon page.

The GBA Glossary

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by jargon, terms • Tags: , , , ,

Usually, we post a definition of a term that we have heard a lot recently, or that is being used in several ways. Today, I am posting a resource for looking up terms related to green building, the Green Building Advisor Glossary.

The glossary is a simple list of terms and acronyms, organized alphabetically. So if you’ve been wondering about LSL, bake-outs, or PEX, among many other terms, it’s worth a little exploration.

THIS POST IS PART OF OUR DEFINITIONS SERIES ON “ECO-LINGO” AND TECHNICAL TERMS.

Zero Net Energy part 2

by jargon • Tags: , , , , ,

photo attribution: CalderOliver at en.wikipedia

Zero Net Energy (ZNE) is a term that is increasingly heard throughout the architecture and building sector, but it is also a term that can mean different things to the different people who use it. This series of posts is an overview of the four common definitions of  ZNE, and a brief expansion on their respective implications in relation to policy structures and physical infrastructure. Part 1 of the post can be found here

The four common definitions of ZNE are: 1. Zero Net Site Energy, 2. Zero Net Source Energy, 3. Zero Net Energy Cost, and 4. Zero Net Energy Emissions. All four of  these calculations are as measured over a calendar year, or on an annual basis. The difference is in the metric (the “thing” being measured) and the boundary (what is included in the calculation). All four definitions can be applied to –and calculated at– a “community” or multiple-building scale as well. In all cases the “net” part refers to how energy is accounted for at the grid level; low energy buildings that are not grid tied would therefore not be under a zero net energy designation.

 Part 2: Zero Net Source Energy

what this is: A source zero net energy building  produces at least as much energy as it uses in a year when accounted for at the source.

what this means: “Source energy” refers to both the energy used by the building and the energy lost in the generation and delivery of the energy to the building. To illustrate the point, think of carrying a bucket of water with a small leak across a room; you then water a plant with it. The ZNE site definition would only be concerned with the water that was applied to the plant; the ZNE source definition would be concerned with both the water that was applied to the plant, and the water that leaked out onto the floor.

pros, cons & considerations:

  • A ZNE source definition can be a benefit if one is striving to be extra conscientious about accounting for energy use and could have benefits depending benefits depending on the fuel mix of your building.

further reading:

P. Torcellini et al., Zero Energy Buildings: A Critical Look at the Definition, National Renewable Energy Lab, 2006.

This post is part of our definitions series on “eco-lingo” and technical terms


Zero Net Energy part 1

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by jargon • Tags: , , , , , , , , , , , , ,
photo credit: Alan Walker

Zero Net Energy (ZNE) is a term that is increasingly heard throughout the architecture and building sector, but it is also a term that can mean different things to the different people who use it. In this series of posts I will give an overview of the four common definitions of  ZNE, and a brief expansion on their respective implications in relation to policy structures and physical infrastructure.

The four common definitions of ZNE are: 1. Zero Net Site Energy, 2. Zero Net Source Energy, 3. Zero Net Energy Cost, and 4. Zero Net Energy Emissions. All four of  these calculations are as measured over a calendar year, or on an annual basis. The difference is in the metric (the “thing” being measured) and the boundary (what is included in the calculation). All four definitions can be applied to –and calculated at– a “community” or multiple-building scale as well. In all cases the “net” part refers to how energy is accounted for at the grid level; low energy buildings that are not grid tied would therefore not be under a zero net energy designation.

Part 1. Zero Net Site Energy

what this is: A Zero Net Energy Building is one that uses no more energy than it can produce on-site within one calendar year (this is the most commonly used definition of the term “zero net energy” at present).

what this means: A “site” can be defined as either the building footprint itself or the building and the property it sits on. In this definition, the building/ building site would incorporate a form of on-site renewable energy such as solar (most common), wind, small hydro or biogas. As mentioned, a ZNE building is still tied to the larger energy grid. For example, a ZNE building that generates energy through the use of solar panels would create a surplus of power while the sun was shining (and the excess power would be fed back into the grid), but would have to draw power from the grid in the evening or during cloudy days. The goal here is for the overall power drawn within one calendar year to be less than or equal to the power generated.

pros, cons & considerations: The chief benefit of this definition is that it promotes deep efficiency at the single building scale. This is because in order to viably (and cost effectively) achieve this definition of ZNE, it is much more desirable to build the lowest energy-use building possible and then add a source or renewable generation. In addition, ZNE sets a concrete goal to achieve and thus can be a more useful target than trying to meet or best shifting baselines as building performance codes change.

However, buildings are built in many types and have many necessary functions- not all of which are compatible with the site definition of ZNE. For example, hospitals, restaurants, industrial activities, etc., may all have a very hard time achieving a ZNE facility because of unusually high energy demands. In addition, high-rise buildings and urban infill sites have their own challenges due to physical constraints (poor solar access, low rooftop-to-building ratio, proximity and density issues, etc.)

The implication here is that if a ZNE site-definition goal is in place on a policy level, at a certain point it becomes necessary to start looking at the issue from a multiple-building, or “community”scale, that would allow energy balancing between buildings to achieve an overall ZNE outcome (this is a simplification, but that is the main point).

Further reading:

P. Torcellini et al., Zero Energy Buildings: A Critical Look at the Definition, National Renewable Energy Lab, 2006.

This post is part of our definitions series on “eco-lingo” and technical terms