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Geos Is Zero Energy Community (Colorado)

Credits: ©2010 Geos Development

Over 300 sunny Colorado days per year and a constant temperature of the Earth at five to seven feet below ground level are the power sources of Geos, the first fossil fuel-free community in the United States. Homes that incorporate passive solar, super insulated building shells, high thermal mass and mobile window insulation provide for optimal solar energy gain and retention. A heat recovery ventilation system provides clean and filtered fresh air and conserves internally generated heat. On hot summer days, an Earth tube chills incoming air to 60°F to cool the home. A district ground source heat pump, which also serves as a back-up heat source for extended cold spells, provides domestic hot water. The entire climate conditioning system and all household electrical equipment are powered by a photovoltaic system tied to the utility grid for net metering. Excess power generation, particularly on hot summer days, is delivered to the grid for storage and to compensate for nights or cloudy daytime needs when electricity is drawn from the grid. Space conditions are thermostat controlled and an energy monitoring system keeps Geos homeowners informed of their specific energy uses. This technology has been used in Europe for many years and is proven, simple and low maintenance. Elevating sustainable community design to a whole new level, the Geos Neighborhood is all about solar efficiency, not just a few solar panels. It is about maximizing space, not having the most space. It is about cultivating a garden not just for beauty, but also to conserve water.


Geos Zero Energy Solar Panel Rendering

The Geos neighborhood in Colorado achieves zero net energy via solar power and geothermal. ©2010 Michael Tavel Architects

A Pattern of Sustainability:

In one neighborhood at Geos, the strategic placement of each home relies on a

groundbreaking “checkerboard design.” This means that every other home sits

on the front of the lot whereas its neighbor sits to the back, minimizing the

shadowing that could impede a home’s solar collection. This innovative, solar-sensitive

pattern differs markedly from a typical neighborhood where homes are

designed with a linear setback – each the same distance from the property line

in a configuration that can block access to the sun. This checkerboard concept minimizes space-wasting side yards and instead creates one larger, courtyard-like front yard or backyard for each home.

Homes are situated so the home’s longest expanse is on the south side to

maximize passive solar collection, and windows are minimized on the colder,

north-facing walls.

One Tree makes a Difference:

The deciduous tree that is planted on the south side of homes was designed to

make the indoors feel more comfortable for residents by providing shade.

Generous tree plantings along the east, south and west sides of buildings will

further provide shade from Colorado’s harsh summer sun.

Where possible, Geos will utilize “living fences” to divide spaces – hedges of

hardy shrubs instead of wood or metal fencing.

Geos offers an extensive and integrated system of pathways and parks. The

neighborhood connects to Ralston Creek Trail. Also adjacent to Geos is the

Croke Canal and a lush riparian habitat.

Community gardens will offer opportunities for residents to grow their own

food. Each green has a different type of fruit tree surrounding it, with the vision

of an orchard co-op.

Advanced Biological Stormwater Management:

Rain gardens will be cultivated throughout the community to harvest water and

filtrate rain and snowfall.

Each green, or percolation park, is a storm water detention basin that also

functions as a neighborhood park, providing play spaces, gardens and bird


Downspout and parking lot tributaries will divert runoff from impervious

surfaces to rain gardens, planting areas, parks and lawns.

Storm water also is managed alongside each streetscape. Each street-side rain

garden is submerged six inches below street level, thus diverting the water to

the tree located alongside the street. Then, cobblestone dissipates the velocity

of the water before it reaches a drain that recycles the excess water back to the

neighborhood parks instead of sending it through a storm drain.

Naturally Powered, People Connected:

Throughout Geos Neighborhood there is an atmosphere of community and

space provided to encourage social activities – pedestrian promenades, common

greens, community gardens and events and meeting places.

As a result of the consistent emphasis on energy and resource conservation and

preservation, and the integration of natural systems into the neighborhood, Geos

Neighborhood also fosters a strong culture of neighborhood environmental

stewardship. It demonstrates how the actions of individuals – in collaboration

with their Geos neighbors – can make a difference in environmental quality.

Significantly raising the bar for sustainable residential development, the Geos Neighborhood in Arvada, Colo., is the nation’s largest net-zero energy, master-planned community. Geos Neighborhood will generate enough renewable energy to offset the annual energy needs of the community’s 250 planned homes.

The Neighborhood incorporates on-site solar and geothermal systems that are designed to supply 100 percent of the community’s energy needs, and work in conjunction with energy consumption patterns that are markedly lower than those found in the nation’s average homes. Below are descriptions of some of the aggressive sustainable measures – among the most uncompromising nationwide – that Geos is taking to achieve a new standard for master-planned community

building in the 21st century.

Maximizing Solar Energy:

Energy from the sun will provide a majority of the homes’ daytime heating

and electric energy through both active and passive solar energy collection.

In addition to state-of-the-art rooftop photovoltaic panels, passive solar

heating will be accomplished through a number of innovative architectural

and community design measures, including:

Checkerboard (i.e., staggered) home placement to ensure most

homes have complete access to sunlight throughout the year.

Buildings stretched east-to-west to maximize south-facing

exposure to the sun.

Strategic placement and sizing of doors and windows on east-,

south- and west-facing walls. There will be minimal use of

windows and doors on colder, north-facing walls.

Scientifically engineered awnings to shield the windows from the

sun in summer, yet accommodate the lower angle of the sun in

winter, allowing solar rays through the windows when they’re

most needed.

Geothermal for 250 Homes:

While the sun will provide the base load of the homes’ heating needs,

geothermal energy will be the heat source for overcast days and during the


Underground geothermal exchange systems will capitalize on the earth’s

constantly moderate temperature, and utilize an underground loopfield to

extract energy that will be used for domestic hot water, space heating in the

winter and space cooling in the summer.

Minimizing Air Leakage:

A leaky home compromises even the most energy-efficient heating and

cooling systems. The homes’ airtight construction will achieve a low 0.1

natural air changes per hour. By contrast, the majority of U.S. homes

currently being built average between 0.5 and 0.7, according to the Energy

Star* program, letting more hot air out and cold air in.

Heat recovery ventilators (HRV) will make the homes’ heating systems even

more energy efficient. This innovative system will transfer 75 percent or

more of the heat from air exiting the home to the fresh, filtered air entering

the home.

Relevant book:
Photovoltaics: Design and Installation Manual


  Geos Zero Energy Meets New Urbanism article (249 kb)

  Geos Annual Energy Performance (678 kb)

  Geos Neighborhood Energy Fact Sheet (363 kb)

  Geos Neighborhood Fact Sheet (368 kb)

  Geos Nieghborhood Master Plan (2,758 kb)

  Geos Zero Net Energy Neighborhood (4,327 kb)


Geos Zero Net Energy Neighborhood Colorado

Geos Neighborhood ASLA Award Entry

Michael Tavel Architects

David Kahn Studio (Colorado, USA)