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Denver’s Green Roof Ordinance Kicks In

A city panel will discuss changes to the new law as its impact comes into sharper focus

Posted on Jan 5 2018 by Scott Gibson

A citizen-sponsored ordinance requiring rooftop vegetation on large, newly constructed buildings in Denver took effect with the start of the new year, but a city task force already is in the works and is likely to make some changes in the months ahead.

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  1. cziwkga via Flickr

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Denver Will Vote on a Green Roof Initiative

Solar panels or garden space would be required on large buildings, but the mayor says the plan goes too far

Posted on Oct 27 2017 by Scott Gibson

A proposal facing Denver voters next month would require developers of buildings larger than 25,000 square feet to cover part of the roof with vegetation or solar panels.

In September, environmental activists narrowly won the right to place the Denver Green RoofRoof system in which living plants are maintained in a growing medium using a membrane and drainage system. Green roofs can reduce storm-water runoff, moderate temperatures in and around the building (by providing insulation and reducing heat island effect), as well as provide a habitat for wildlife and recreational space for humans. When properly constructed, green roofs can increase roof durability because the roof assembly’s air and water barriers are buffered from temperature fluctuations and UV exposure. Initiative before voters by collecting just 45 more petition signatures than they needed, The Denver Post reported.

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  1. MSU Infrastructure via Flickr

Denver Developer Focuses on Zero-Energy Homes

Denver, CO

May 28 2015 By | 1 comments

General Specs and Team

Location: Denver, CO
Bedrooms: 3
Bathrooms: 2.5
Living Space : 2115 sqf

Builder: Bill Rectanus, New Town Builders

Energy consultants:Peter Oberhammer, EnergyLogic, Inc.


Foundation: Conditioned basement with R-19 interior wall insulation

Wall construction: Double-stud 2x4 walls, advanced-framed, with 9.5 inches blown fiberglass (R-40.7)

Windows: Double-pane, low-eLow-emissivity coating. Very thin metallic coating on glass or plastic window glazing that permits most of the sun’s short-wave (light) radiation to enter, while blocking up to 90% of the long-wave (heat) radiation. Low-e coatings boost a window’s R-value and reduce its U-factor., vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate).-framed, U=0.25, SHGCSolar heat gain coefficient. The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.=0.27

Roof: Vented attic framed with 14-inch raised-heel trusses

Attic insulation: R-50 blown-in fiberglass attic insulation


Air leakage rate: 2.11 ach50

HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. A home matching the reference home has a HERS Index of 100. The lower a home’s HERS Index, the more energy efficient it is. A typical existing home has a HERS Index of 130; a net zero energy home has a HERS Index of 0. Older versions of the HERS index were based on a scale that was largely just the opposite in structure--a HERS rating of 100 represented a net zero energy home, while the reference home had a score of 80. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. Index: 38 without PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.; -3 with an 8-kW PV system

Estimated annual energy use: $1,414 without PV, $5 with PV

Actual annual energy use: Unknown

PV arrays are an available option

Space heat and cooling: Air-source heat pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps., 12.7 HSPF, 19.8 SEER(SEER) The efficiency of central air conditioners is rated by the Seasonal Energy Efficiency Ratio. The higher the SEER rating of a unit, the more energy efficient it is. The SEER rating is Btu of cooling output during a typical hot season divided by the total electric energy in watt-hours to run the unit. For residential air conditioners, the federal minimum is 13 SEER. For an Energy Star unit, 14 SEER. Manufacturers sell 18-20 SEER units, but they are expensive. , with forced-air ductwork for distribution; 97.3 AFUEAnnual Fuel Utilization Efficiency. Widely-used measure of the fuel efficiency of a heating system that accounts for start-up, cool-down, and other operating losses that occur during real-life operation. AFUE is always lower than combustion efficiency. Furnaces sold in the United States must have a minimum AFUE of 78%. High ratings indicate more efficient equipment. gas furnace for backup.

Ventilation: Exhaust-only 15-watt fan rated at 71 cfm

Domestic hot water: 0.947 EF(EF). Efficiency measure for rating the energy performance of dishwashers, clothes washers, water heaters, and certain other appliances. The higher the energy factor, the greater the efficiency. In some appliances EF reflects the percentage of energy going into the appliance that is turned into useful energy. tankless gas water heater

Lighting: 100% CFLCompact fluorescent lamp. Fluorescent lightbulb in which the tube is folded or twisted into a spiral to concentrate the light output. CFLs are typically three to four times as efficient as incandescent lightbulbs, and last eight to ten times as long. CFLs combine the efficiency of fluorescent light with the convenience of an Edison or screw-in base, and new types have been developed that better mimic the light quality of incandescents. Not all CFLs can be dimmed, and frequent on-off cycling can shorten their life. Concerns have been raised over the mercury content of CFLs, and though they have been deemed safe, proper recycling and disposal is encouraged.

Appliances: All Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners.

Water Efficiency

WaterSenseProgram developed and administered by the U.S. Environmental Protection Agency to promote and label water-efficient plumbing fixtures. compliant fixtures

"Smart" recirculation pump that learns occupants' behavior

Green Materials and Resource Efficiency

Beetle-kill lumber used for all framing lumber

Roadways, bridges, and bike paths use recycled concrete


DOE Zero Energy Ready

DOE Energy Star

EPA Indoor airPLUS

Double-stud walls effectively reduce thermal bridging

A Denver-area developer, New Town Builders, is aiming to make all of its new homes zero-energy-ready by the end of 2015.

“Our goal is to be 100% U.S. Department of Energy (DOEUnited States Department of Energy.) Zero Energy Ready certified on all of our single-family homes,” said Bill Rectanus, vice president of New Town Builders, which plans to build 150 single-family homes in the Denver metro area in 2015.

Courtesy U.S. Department of Energy

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  1. New Town Builders

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In Denver, a Conference for Energy Efficiency Retrofitters

The Colorado Energy Star Summit aims to cultivate interest in careers focused on home-performance improvements

Posted on Nov 24 2010 by Richard Defendorf

Nowadays, discussions about job prospects in the homebuilding and remodeling sectors often zero in on energy efficiency upgrades. The stimulus-funded expansion of the Weatherization Assistance Program raised the profile of weatherizing, and tax incentives and affordable-financing programs have helped drive demand for certain types of renewable-energy systems.

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Image Credits:

  1. Affordable Comfort Inc.

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