New Building Opening mid 2010! 

Our Green Museum, A building to suit the climate

– Enchanted Circle Gateway Museum, Eagle Nest, New Mexico

What started as a quest to design a practical building for our Museum in the mountains in northern New Mexico quickly became an endeavor for many things green, benefiting one mission of a museum to lead by example. The following is a description of what we incorporated into the building to provide an example to visitors and our community. Our discovery is that green and sustainability is not expensive, it actually saves money. More importantly it is a critical step toward saving for our children the world which we take for granted.

Our site planning – There were four prerequisites to satisfy our desire to reduce our dependence on fossil energy.

  
1. In order to allow the most nature has to offer, our most important consideration was site selection. Selecting a site which allows exposure to winter sun is critical. This was known and practiced by the native Anastasie centuries ago but has been overlooked in modern times as an element in building design.   

 
2. Next in importance is the positioning of the building on the selected site to take full advantage of the sun, allowing the sun into the building. Collecting this free energy involved moving some of the windows from the North side of the building to the South side.    

3.  Third is collecting the energy and providing storage for it. Our design solves both collecting and storing the sun’s energy with no moving parts, further reducing our demand on fossil energy. The hallmark of a well designed solar building is that it will provide a comfortable environment day and night. Every building exposed to the sun will warm during the day, however if the heat is not stored, interior temperatures will soar to uncomfortable levels, forcing the occupant to ventilate the building and the loose heat which could have been better used at night. Our solution was to utilize a state of the art passive solar thermo siphon foundation which does not require purchased energy for operation or constant oversight by the occupant. Details on our storage system are provided below.

  
4. Next in importance is properly insulating the building to retain the heat. It is important to recognize that even the new green building codes specify only the bare minimum insulation requirements.

The museum site was once home to a Chinese mining camp located on Willow Creek, the discovery site initiating the local gold rush of the late 1800’s. Large rocks were sorted and stacked as the Chinese prospectors toiled to collect the gold flour deposited in the ancient stream bed. Decorative moss rock is now plentiful on the site and will be protected during construction to preserve this history. We plan to let nature take care of the museum landscaping since it will display exclusively local plants and grasses in the natural setting.

We made every effort to utilize local materials to reduce energy used for transporting. Locally harvested logs will be used to fabricate the building. This is both for ecological reasons as well as aesthetic since a log cabin will more represent bygone days in this area. The concrete floor will be left exposed with a stain finish. This reduces allergens and eliminates the need for carpet and other non renewable flooring materials, some of which can off-gas toxins and/or provide fuel for a fire.

High efficiency insulated glass windows are used. Low e emissive coated glass and encapsulated gas increases the ability of the window to retain heat in the building. Selected windows are operable to allow for cross ventilation on cool summer nights to allow the solar foundation to release heat and act as a cooling source during the day.

We are using electric on-demand water heating to reduce fuel consumption, as it heats only when a faucet is turned on. This system is available in gas or electric. Since we plan to produce our own electricity in the future, the electric unit will be utilized. The electricity will be produced by two means; sun and wind, because both are abundant here. We collect rain and snow melt and recycle water for a gold panning steam by diverting water from the roof to a pond. The pond water is pumped to the top of a short stream fabricated for the purpose of aerating the water and also allowing participants to pan. The stream and pond also provides a small wetland for wildlife. 

A high efficiency wood pellet stove is used as winter backup to the solar heating system. This provides heat in the event of a string of sunless winter days. To provide additional energy conservation, the stove’s combustion air is provided from the outside so as not to deplete the warmed interior air.

In this tightly constructed energy efficient building the air must be changed often to remain fresh, however this process can lose heat to the outside as air is exhausted.  A special positive pressure system was developed to solve this problem. It also solves the problem of negative interior pressure which causes cold droughts when outside air leaks into a building, typical of even a tightly constructed building because of required air vents.

The positive pressure system collects heat which would otherwise be lost out the chimney and places the building under a slight positive pressure,  preventing cold air infiltration. Outside air is forced over the exhaust chimney pipe providing a positive interior pressure. This outside air is warmed by the chimney before being passed through the solar foundation where the heat is stored for later use.

In addition a solar powered micro fan captures heat trapped at the ceiling and cycles it through the solar slab, allowing the heat to be recycled and stored, further reducing demand on heating fuel.

Interior spot lighting utilizes low energy consumption LED technology. Light Emitting Diodes have made great strides in the flashlight, traffic signal and auto industry and will eventually supply the interior lighting market. We are pushing the envelope by using local expertise to fabricate our lighting fixtures. The energy needed to power LED lighting is radically lower that even the highly efficient florescent spiral bulbs.

Details on the solar foundation:

Solar storage is the flywheel which keeps interior temperatures comfortable in every season. The basic requirement is that it moderate interior temperatures year round. It accomplishes this by transferring daytime heat to nighttime in the winter. It must also transfer the cool of the night to day during the summer. Designed correctly, it adds little extra initial cost but provides substantial energy savings every year for the life of the building. As the cost of energy increases this savings increases.

Moving some of the windows from the north wall of the building to the south wall has a doubling effect in the winter. It provides the necessary south facing glass and also reduces heat loss to the north. The then low southern sun reaches far into the building. However, during the summer the sun is overhead and adds no heat to the floor, allowing it to cool to lower temperatures overnight thus cooling this uniquely designed building in the summer.

The heart of the design is a specially designed concrete floor which allows it to act as a thermal mass, easily absorbing and storing the sun’s heat. Loss to the ground is minimized by floating the entire foundation system on a layer of insulation. Correctly sized, the floor prevents the building from overheating during the day and provides warmth to the interior during cold winter nights.

How it works:  

When the sun strikes the floor during the day, air passages built into in the concrete slab will circulate the warmed interior air of the building through the slab without the use of circulating fans or electricity. The design creates a natural thermo siphon effect. Air in the slab is warmed by the sun causing it to rise out of air passages in the floor on the sunny south side of the building. The heavier cool air along the north wall sinks down through vents into the slab. The result is a continuous flow of interior air circulating through the concrete foundation, allowing the floor to evenly absorb heat from the air as long as the sun is striking the slab.

The air passages are created during construction by aligning hollow cinder blocks end to end from north to south. This is topped with a calculated layer of concrete. The carefully sized thermal storage mass provides important thermal inertia which tends to hold the building at a steady temperature both during cold winters as well as warm summers. This thermal stability has the added advantage of reducing dependence on fossil fuel by allowing downsizing of backup heating and cooling to less than worst case conditions as is common in conventional design. Using a smaller backup system saves considerable money and energy over both the short and long term.

The solar slab design parameters have been made available by the inventor in his book The Passive Solar House by James Kachadorian. His Vermont based company, Green Mountain Homes, built many homes in the 80’s and 90’s using his patented design. The design was proven in the north east where solar is not considered abundant. New Mexico’s Sandia Laboratory published their test report on Green Mountain Homes and is available under Reference Number 79-0824. The patent expired in 1997, interest increased and demand prompted turning his experience into a book. A local home which is testing the design reports very favorably on the comfort level during the winter and summer. Daily temperatures were monitored and recorded during construction using minimum/maximum thermometers. Before occupancy, the installation of backup heating and breaking the thin layer of concrete to open the vents, there was no threat of frozen pipes as interior temperatures never fell below 54 degrees while exterior temperatures dropped to negative 47 degrees during the winter construction phase. Daytime temperatures over this period never exceeded 75 degrees.

On a sunny day in February, the museum’s solar foundation, which has 65 tons of thermal mass floating on foam insulation, will reach a design temperature of 65 degrees Fahrenheit. During the night the slab will radiate underfoot heat to make up for heat lost through windows, ceiling and walls. With an overnight outside temperature of negative 20 degrees Fahrenheit, the slab temperature will drop to 60 degrees Fahrenheit. Backup heat is not used overnight if the thermostat is set below this temperature. The morning sun again starts the thermo siphon cycle, warming the tons of concrete. This continues without caretaker intervention, keeping the building comfortable even while no one is there.

As an added conservation measure, the museum is pre-wired for future use of alternative sources of electrical power including solar and wind. Since the building is connected to the grid, excess power generated by the building could be metered into the electrical grid, offsetting the energy bill and providing energy to others. Our first source of alternative energy will be photo voltaic panels. Over time additional panels will be installed to provide excess energy. A vertical axis wind turbine will be added to provide power when the wind is up. This wind turbine design generates power at low wind speeds, makes little noise, is not visually objectionable, requires little maintenance and does not hinder bird migration.

Resources:

The Passive Solar House by James Kachadorian


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