Some of the terms and technology associated with NSCC's new Green Building are explained below.
Chilled beams use chilled water to remove heat from rooms in the same way as the geothermal systems does. Active chilled beams combine a ventilation system with this process of bringing chilled water into rooms, moving fresh air across the water as it blows into the room. Water in chilled beams only needs to be 55-59° to cool rooms, as opposed to the 42-45° in traditional systems, requiring significantly less energy to chill the water, and making a geothermal cooling system more viable. Active chilled beams are incorporated throughout the new building.
Carbon footprint is a measurement of all greenhouse gases we produce in our day-to-day lives, by burning fossil fuels for electricity, heating, transportation etc. Carbon footprint is measured in terms of the amount of carbon dioxide emitted. For example, burning one gallon of gas creates 20 pounds of carbon dioxide and heating an average house about 4 tons annually.
A carbon offset is a certificate representing the reduction of one metric ton (2,205 lbs) of carbon dioxide emissions, the principal cause of global warming. Although complex in practice, carbon offsets are fairly simple in theory. If you develop a project that reduces carbon dioxide emissions, every ton of emissions reduced results in the creation of one carbon offset. Project developers can then sell these offsets to finance their projects. There are hundreds of different types of carbon reduction projects. For example, a wind farm generates clean energy, which reduces carbon emissions from coal-burning power plants. In order to finance its operations, a wind farm can sell these reductions in the form of carbon offsets.
There are many ways to use geothermal energy in the heating and cooling of buildings. All involve the circulation of liquid into the ground to take advantage of the earth's relatively constant temperature. In parts of the world with high volcanic activity, people may use open systems, taking advantage of the extremely hot water found underground to heat their buildings, pumping it back underground when they're done. NSCC, however, is using what is called a closed-loop system, drilling wells 500 feet into the ground. Liquid is pumped through U-shaped pipes placed in these wells, resurfacing at the same temperature of the surrounding earth—about 52° F. In summer, this 52° liquid is circulated around the building, absorbing much of the building's heat and bringing that heat outside, cooling the building. The ground acts as a "heat sink," absorbing the heat from the liquid, which comes back up out of the wells at 52° and the process begins again. In wintertime, when air temperatures are often below freezing, it usually takes a lot of energy to heat the water that heats the buildings to a comfortable 70°. But when the liquid is already 52°, we only have to heat it 20° more before circulating it around the building, reducing the building's energy demands, energy costs, and carbon emissions. NSCC has drilled 60 wells to service the new building.
Geothermal Heat Pumps work the same way as a regular heat pump except that its source of heat is 52° water generated from geothermal wells. Heat pumps use a refrigerant that has the ability to absorb heat, even from the low temperature geothermal well water. This refrigerant is then compressed which heats it further. Air is then blown over the coils with a warm refrigerant inside and the result is warm air at the desired temperature.
NSCC has installed a green roof over the student services section of the new building. This means that this section of the roof is be covered with soil and vegetation, increasing insulation of the building and thereby reducing heating and cooling costs. The green roof will also increase the roof's lifespan, filter pollutants and carbon dioxide out of the air, filter pollutants out of rainwater, reduce storm water runoff, provide habitat for plants, insects, birds, and reduce ambient temperatures by preventing the roof from absorbing the sun's radiation and re-emitting it as heat, as dark-colored traditional roofs do.
Passive solar heating is the direct heating of a building by sunlight. The new building will be oriented towards the south with large windows on the south-facing side in order to take advantage of sunlight for light and heat throughout the day (in most of the Northern Hemisphere the sun reaches its highest point towards the south, the direction of the equator). By incorporating shading devices over the windows, the high summer sun will largely be prevented from entering and heating the building, while the low sun in winter will still be able to do so.
Renewable Energy Credits are certificates issued by the government or a regulatory agency to energy producers who utilize environmental methods to generate electricity such as solar, wind, geothermal, biomass, etc. These credits can then be sold or traded on the open market. By purchasing RECs, building owners can ensure that some of the energy their building consumes is replaced on the grid from a clean, renewable source. The goal of these credits is to encourage renewable energy production.
Solar photovoltaic (PV) cells convert sunlight directly into electricity. Individual cells are fairly small, so when more electricity is needed than a single cell can provide, such as for a building, the cells are arranged on solar panels, which are then placed in arrays. To work, photons (light particles) from sunlight hit the panels and are absorbed by silicon and other materials in the cells. The photons knock some electrons loose from their atoms, allowing the electrons to flow through the material and produce an electric current (electricity). NSCC has an array of south-facing panels on the roof of the Health Professions & Student Services building.
ZNEB or Zero Net Energy Building is one that is optimally efficient and, over the course of a year, generates energy onsite, using clean renewable resource, in a quantity equal to or greater than the total amount of energy consumed onsite. When needed, the building will use power from the grid, but when production through solar panel, wind or any other renewable source, exceeds the use, excess power will be sold back to the power company. This means that when building operates under no load, when it is not in use, all produced power will be put back onto the grid. This creates clean energy and eliminates emissions of harmful gases created in traditional energy production.