How It Works

The CEED features new technologies that will help our environment. Our home will show off new ways to improve the ordinary person’s way of living and helping our planet.

Energy Efficient and Water Saving Appliances

High efficiency washing machines use 50% to 60% less energy than regular washing machines. They also require less detergent. High efficiency dishwashers use a lot less water than regular dishwaters. Refrigerators that are energy efficient save a lot of energy.

Rainwater Harvesting 

Rainwater harvesting is the collection and storage of rainwater. This system is going to take rainwater and save it to use for our home. The system will use rainwater that comes off of the roof from a storm and then is captured and stored underground. It is then disinfected and filtered. We will then use this water for our toilets, sinks, and other water appliances.

Earth Berming

Earth Berming is pushing earth (soil) against the side of a building for external thermal mass to reduce heating and cooling loss and to easily maintain indoor air temperature.

Solar Thermal Systems tv2

Solar thermal energy (STE) is a technology for transforming solar energy into thermal or heat energy. This may be used to heat and cool buildings and to heat water for use in buildings and swimming pools. Most solar thermal systems are composed of three main parts: solar collector, insulated heat transport piping, and heat storage. In colder climates, some type of freeze protection system may be needed.

The three types of solar collectors used in residential applications are: flat-plate collectors which are typically used for solar pool heating, integral collector-storage systems which pass cold water through the solar collector to heat the water (used in mild climates), and evacuated-tube solar collectors which consist of parallel tubes containing a refrigerant.

At CEED, a closed evacuated-tube system is used. It consists of 30 elongated tubes located on the roof in two solar collectors. Because the climate in Rocky Mount can drop below 32°F, propylene glycol, an antifreeze solution, is heated in the solar collector. The heated liquid is circulated from the solar collector through a heat exchanger connected to a storage tank. Potable water is warmed by the tubes containing heated propylene glycol. The heated water then goes to the storage tanks, while the cooled propylene glycol is piped back to the solar collector to be reheated. An added benefit of this closed system is that it requires little maintenance and can also be used for heating and cooling the building through the energy recovery ventilation system.

Solar Orientation tv2

Passive solar design places a home or building to take full advantage of the sun’s energy for the heating and cooling of the living spaces. The building should be oriented so that the long side faces south and the short sides face east and west. Areas most frequently used for living should be located on the longer south side. Facing due south maximizes the incoming solar energy, or insolation, to provide natural lighting and free heat. The three key components of passive design are: appropriate solar orientation, the use of thermal mass, and appropriate window placement and ventilation. Earth berming can also be integrated into the system.

The CEED building is oriented due south with operable windows to allow incoming radiant heat and ventilation as needed. All of the exterior walls are poured concrete to provide thermal mass. The interior floor is a six inch insulated pressed concrete slab that stores free heat. Floors of this type may be stained or covered with conductive material such as tile. Heat stored in the floor (thermal mass) is released back into the interior during the night.

To moderate temperature extremes, CEED is earth bermed on the north, east, and west facing sides. This feature allows the building to be cooler in the summer and warmer in the winter. Since CEED is located in the temperate zone, it is not necessary to berm the north side higher than six feet, and the east and west sides two to three feet.

Photovoltaics

The word photovoltaic comes from the words photo meaning light and volt referring to a measurement of electricity. Photovoltaic cells, sometimes called PV cells or solar cells, are made up of silicon. Solar cells supply energy to items that are powered by batteries or electrical power. Sunlight strikes the solar cell, causing electrons to move which produces an electrical current. Conversion of solar energy to electrical energy occurs instantly.

Two different types of solar electric systems can be used to generate electricity for homes and buildings. The stand-alone system uses batteries to store electricity produced by PV cells. This system does not connect to the utility power grid and requires more maintenance such as refilling water in the batteries. The grid-tied system uses an inverter in the building to convert Direct Current Electricity (DC) into Alternating Current Electricity (AC), which allows it to be used by the building and other consumers on the grid. When there is low demand for electricity in the building, excess PV power flows to the grid causing the utility meter to turn backward, essentially selling electricity back to the utility company. This policy is known as net metering. The only maintenance with the grid-tied system is the adjustment of the solar panels to the changing angle of the sun throughout the seasons.

On the roof of CEED, solar panels are made of racks of cylindrical tubes mounted horizontally and packed closely together. These cylindrical panels absorb solar energy from every direction (direct, indirect, and reflected light); therefore, the panels do not have to move to track the sun. The panels also allow wind to blow through them. A second type of solar panel is a flexible PV film that is laminated to the flat pan surface of a metal roof panel. The thin film system is similar to a cool roof surface because it acts as a solar reflectent. In addition, there is a tracking flat (rigid) panel which can move along two axes. This panel is mounted atop a pole, near the building, and constantly tracks the path of the sun. The tracking system is the only device that uses electricity from the grid-tied system. The remainder of the electricity is sold back to the power company.

Wind Energy  

Wind is air in motion caused by the uneven heating of the earth’s surface by radiant energy from the sun. Wind is a clean, renewable energy source, free to use, and produces no air pollution. Energy can be extracted from the wind by a rotary device called a wind turbine. As the wind pushes against the blades of the wind turbine, it makes them spin. This powers a generator to produce electricity. A wind turbine consists of blades, shafts, gears, a generator and a cable. Working together, these parts convert the wind’s kinetic energy to mechanical energy and then to electrical energy. The size of a turbine and the speed of the wind determine the amount of electricity produced. While a small turbine may power one home, large turbines can produce enough electricity to power 1000 homes. Wind farms or clusters of wind turbines provide power to the electricity grid which is the network of power lines across the entire country.

The CEED campus contains two different wind turbines. The horizontal axis turbine is a Skystream 3.7 rated at 1.8 kW for use as a residential turbine. A small inverter in the hub converts to AC power and feeds it directly to the building. The second turbine, Windspire, is a vertical axis turbine appropriate for urban, suburban and rural environments. Electricity is immediately available to the building. Although the campus is not an optimum wind site, the turbines do feed electricity to the grid providing a reduction in the energy bill for the school.

Geothermal Heat Pump

A geothermal heat pump is an underground heating and/or cooling system. It transfers heat from the ground in winter and into the ground in summer using a liquid refrigerant that is circulated through long loops of underground pipe. Typically, this is a closed loop system. Based on the arrangement of the loops, there are four types of closed loop geothermal systems. The horizontal ground loops are shallow and may be 400-600 feet long. Vertical ground loops are used in extreme climates, in rocky terrain, and where space is limited. In this type of system, loops of pipe are dropped into deep holes. Slinky coil geothermal ground loops are popular in residential systems because they are more economical and are shorter than traditional horizontal ground loops. Geothermal pond loops require a pond or lake that is at least a half acre by eight feet deep, where the coils of pipe are installed in the bottom of a body of water. Geothermal systems are twice as efficient as conventional heat pumps and 50 percent more efficient than gas furnaces. This is due to the liquid to air heat exchange instead of the air to air exchange in the average heat pump.

At CEED, the slinky coil geothermal ground loop system is used. Slinky coils, rather than straight pipe, are laid out along the bottom of a wide trench. Propylene glycol, a refrigerant, is pumped through the loop system. Ideally, this system will rarely be used as the primary source of heating and cooling due to the efficiency of the CEED building.

Overhangs and Green Roof  

Roof overhangs are like putting a cap on the building. They are structures that are designed to block the high-angle summer sun, and allow the lower winter sun to penetrate the building. Overhangs are the most effective on the south facing side and the upper level of a multistory building. There are several types of overhangs, which may include awnings, shade screens, or trellises.

The trellises at CEED are permanent structures that extend from the roof overhang. The material used in the trellises is a recycled structural composite (RSC) made by Axion International from a blend of recycled plastic. The durable RSC is stronger, lighter, and will not rust, splinter, rot, absorb moisture, or leach toxic chemicals into the environment. Because it is impervious to water, insects, or marine parasites, RSC can be used in making infrastructure products for bridges.

A green roof is a roof that is partially or completely covered with plants. A green roof can be characterized according to the weight load on the building. An extensive green roof has a lower load bearing capacity, while the intensive type can support lawns, walkways, playgrounds, and even ponds. The extensive roof is lower in cost to create and maintain, needs no irrigation, and is covered with mosses, sedum, herbs and grasses. The intensive green roof is higher in cost and maintenance, needs regular irrigation, and uses plants such as perennials, shrubs, and trees.

At CEED, shade is provided in the summer by the planting of deciduous vines such as grape, wisteria, clematis, or jasmine on the trellises. Landscaping around the building includes ground plants, hanging baskets and large pots. In the winter, after the leaves drop, the sunlight can freely enter the windows and warm the building.

The CEED building utilizes the extensive green roof system, where sedum is grown along the upper roof line ridge. Although it does not completely cover the roof, it does provide a model for capturing precipitation and absorbing heat. It also serves to filter pollutants and carbon dioxide from the air.

 PassivHaus  

The term PassivHaus refers to a specific standard of construction for buildings which provide comfortable, healthy living conditions year round. It is considered to be passive because it heats and cools itself without an active heating and cooling system.

The basic features of PassivHaus construction are:

 Passive use of solar energy with southern orientation and shade
 Good insulated exterior shell
 Energy efficient window glazing and frames
 Building envelope to maintain air-tightness
 Passive pre-heated fresh air
 Highly efficient heat recovery system (air/air heat exchange)
 Solar collectors or heat pumps to supply hot water
 Energy-saving appliances

CEED is a passive solar building oriented to the south with an overhang and trellises for shade. The floor is pressed concrete with six inches of insulation. The building uses a highly efficient geothermal heat pump for heating and cooling. Solar thermal energy is also used for heating the water and for heating and cooling through the energy recovery ventilation system.

Constructed by Structures Design/Build of Roanoke, Virginia, CEED has been certified by the Passive House Institute US for meeting PassivHaus energy-efficiency standards. It is the first public school building in the country to meet PassivHaus standards and the only building in the world where design components are taught in the building.

CEED has been built to meet and exceed PassivHaus specifications. To be certified, the building must use 90 percent less energy for heating and cooling and have 70 percent lower carbon dioxide emissions than a typical building. The air to air heat exchanger is 93 percent which exceeds expectations.

 

 

 

 

 

 

The Leonard A. Gereau Center for Applied Technology & Career Exploration | 150 Technology Drive | Rocky Mount, Virginia | 24151 | Copyright © CEED 2012