MECHANICAL

The mechanical system for our home is an integrated system made up of the heating, ventilation and air conditioning system (HVAC), the radiant heating system, and the plumbing system.

The HVAC system uses electricity generated by the photovoltaic system. A complementary baseboard radiant heating system will use excess hot water warmed by the solar thermal system. This system will also supply the hot water needed for tasks such as washing dishes and showering.

HVAC
The HVAC system is designed to be energy efficient and to provide a comfortable environment in the home year round. The system has four components: an electric heat pump, an air handler, a digital thermostat, and the ductwork. This system has a Seasonal Efficiency Rating (SEER) of 15.05. This rating was obtained by mixing equipment to gain an optimal operating efficiency. By using alternate configurations and options, the overall power use will be less than a conventional heat pump system.

Heat Pump
A heat pump looks just like an air conditioner, but it does double duty,
acting as a heater in the winter and an air conditioner in the summer. These units' pumps provide heat transfer to a high temperature region from a low temperature region. This process, opposite to the natural flow of heat, is accomplished at the expense of work input.

In the winter a heat pump captures the heat that is always present in the outside
air --- even down to zero degrees or less --- and pumps it into your home.
In the summer, because of its unique switchover valve, a heat pump
reverses the flow of refrigerant in order to pull the heat out of your home
and transfer it outdoors. It's this switchover valve that effectively converts
a heat pump from a heater to an air conditioner, giving you the best of both worlds.
After careful evaluation, our team chose a Trane model TWY018B heat pump with an 18,000 BTUH capacity condenser.
Link to Trane TWY018B
http://www.trane.com/residential/rightproduct/esx11400.asp

SEER
SEER or seasonal energy efficiency ratio provides information about HVAC efficiency. In addition to adequate cooling capacity, a unit should be efficient. A more efficient unit will cost less to operate. In fact, many of the new energy efficient air conditioning units have operating costs that are half those of older, less efficient models.

SEER indicates how much cooling is provided per watt of electricity on a seasonal basis. The higher a unit's SEER, the higher its efficiency. Using SEER, the consumer can easily compare the efficiency of two units. For example, a unit with a SEER of 10 will be twice as efficient as one with a rating of 5, and should cost approximately half as much to operate. Manufacturers are required by law to publish energy efficiency ratings and estimated annual operating costs of their residential air-conditioning systems.

Link to BTUH

A British thermal unit (Btu) is an English standard unit of energy. One Btu is the amount of thermal energy necessary to raise the temperature of one pound of pure liquid water by one degree Fahrenheit at the temperature at which water has its greatest density (39 degrees Fahrenheit). This is equivalent to approximately 1055 joule (or 1055 watt-seconds).
The Btu is often used as a quantitative specification for the energy-producing or energy-transferring capability of heating and cooling systems such as furnaces, ovens, refrigerators, and air conditioners. The heat output of equipment is often specified so that it can be considered when planning the size of climate control systems in buildings. 3.7 Btus per hour is equivalent to 1 watt of heat dissipation.

Air Handler
The job of an air handler is to move the air heated or cooled by the heat pump throughout the home. Our team chose a Trane Air Tite series model TWE031E13F air handler with a capacity of 31,000 BTUH. This air handler is equipped with a variable speed motor that operates at 600 CFM. In addition the air handler has a ramping system at startup to reduce spikes in power consumption.
Link to Trane Air Handler
http://www.trane.com/residential/rightproduct/estwe.asp

Link to CFM

Thermostat
The thermostat is the control point for the HVAC system. Our team chose a Trane TAYSTAT570. This digital system provides superior temperature accuracy and precision compared to a non-digital system.

Link to Trane TAYSTAT570
http://www.trane.com/residential/rightproduct/thermostats.asp

Ductwork
The ductwork for our home is designed to provide an even flow of climate-controlled air throughout our home. This ductwork carries air from the heat pump to the house and returns air from the house to the heat pump in an energy efficient manner.

Our home uses a combination of fabricated aluminum insulated ductwork and flexible ducting.

Link to ductwork diagram - Coming soon

Radiant Heating System

A radiant heating system was chosen to complement the HVAC system. During the evening hours when heating may be required, the system makes use of excess hot water produced by our home's solar thermal hot water system to heat the house. The HVAC heating unit will only come on if the radiant system fails to maintain the target temperature, thereby reducing energy consumption. Solar thermal systems have energy efficiencies in the 50 to 60 percent range, much higher than the 10 to 15 percent efficiencies of typical solar photovoltaic systems.

After extensive study and numerous heat load calculations, our team chose a thirteen- linear foot floor heating system produced by Runtal North America Incorporated.

Link to Runtal Incorporated
http://www.runtalnorthamerica.com/baseboard-heating.html

Link to system diagram - coming soon

Plumbing

The plumbing system consists of several components that are standard equipment in most homes along with some that are not so standard and are related to the home's solar nature and the unique contest requirements. This system will provide water needed for everyday use in the home and will recycle as much water as possible. This system has two parts --- supply and drainage.

A major concern in designing this system was to use the smallest amount of energy possible in heating water and transporting it to its destination. Extra attention was paid to the insulation of these pipes. Parasitic losses through piping can add up over the course of a 24-hour period. Urethane insulation with an R-10 rating was used to minimize losses. The system balances innovative design with all pertinent code requirements and IRS 2000 mandates as established by the US. Department of Energy.

Supply

The supply components of our system include: the flat plate collectors, a water heater, water tanks, pumps, hard lines, a dishwasher, a washer/dryer, the shower, the toilet, the bathroom sink and the kitchen sink.

Flat Plate Collectors

Using electricity to heat water consumes a lot of energy. The decision to use flat plate collectors to heat the water for our home conserves a significant amount of energy. When you compare the efficiency of the flat plate system (50-60%) in capturing the sun's energy to the efficiency of our photovoltaic system (12%), the benefit of using flat plate technology is obvious. Our calculations show that for most of the year, this system will not only provide enough energy to meet our hot water needs but will also produce enough energy to provide some heat for our home.

Our team chose two Mojave 408 thermal flat plate collectors manufactured by Heliodyne, Inc.

Mojave 408 thermal flat plate collectors
These four-foot by eight-foot flat solar thermal flat plate collectors use the sun's energy to heat a propylene glycol solution that flows through the collectors. A heat exchanger transfers the heat at 90% efficiency from the propylene glycol to water in a well-insulated 80-gallon hot water storage tank.

These collectors were chosen for their superior collection and loss characteristics.

Link to flat plate collectors
http://www.heliodyne.com/solar_hotwater/solar_hot_water.htm

Water Tanks
A 240-gallon insulated water tank contains the water supply for our home. This tank will be filled at the beginning of the contest. Our system also includes an 80-gallon hot water tank.

Water Pumps
Because the water coming into our home will not be pressurized (as is the case with a normal city water supply) pumps will be used to move the water through the plumbing system. Pressure sensor in the tanks will turn the pumps on and off when pressure in the tanks reaches set levels.

Hard Lines
The hard lines that transport water to the various part of the plumbing system are PVC. This material was chosen because it is easy to install, inexpensive and provide ease of maintenance.

Dishwasher
The high-efficiency dishwasher manufactured by Fisher and Paykel, model number DS603, uses much less water than a traditional dishwasher, has a genuine half-load option and a delay start option which allows us schedule a wash when our energy draw is low.

Link to
www.fisherandpaykel.com

Washer Dryer
The compact Equator model EZ 3600CEE washer dryer combination uses much less water than a conventional washing machine, has six wash cycles, and a very fast spin cycle which does an excellent job of removing water from the items being washed which shortens drying time. This particular model requires both hot and cold water supply lines.

Link to washer/dryer
www.compactappliance.com

Shower/Toilet/Sinks
In choosing plumbing fixtures for our home, our team looked for functional items that fit into compact spaces and allowed us to meet all ADA requirements. Whenever possible, we chose fixtures that conserved water. For instance, the showerhead has a flow adaptor that reduces water consumption. The toilet uses much less water than a standard unit.

Link to shower site

Link to toilet site

Link to sink site

Drainage System

The plumbing system for our home must be self contained. That means that we must have a collection system capable of handling all wastewater from the house. Our home's system consists of hard lines, a filter, waste tanks, and a pump.

Hard Lines
The PVC hard lines transport water to and from the various parts of the system.

Filter
A particle filter will remove contaminants from wastewater coming from some parts of the system that will enable it to be recycled back into the supply system.

Waste Tanks
The waste tanks will take the place of a traditional septic system and provide a holding place for unrecycled wastewater coming from the toilet, dishwasher and washing machine. This tank will be a flexible bladder that will be located under the house.

Pumps
Our home, due to the unique constraints of the competition, does not have enough fall from gravity to promote natural drainage. Instead, pumps will be used to move wastewater through the house. A pump will also lift recycled water back up and into the supply system.

Temperature and Humidity Control Sensors

A thermocouple network will monitor the temperature of the water and air system to optimize energy consumption throughout the house. This network will use Omega 26 gauge K-type thermocouples and a wall-mounted readout device that cycles through all of the sensor locations at pre-set intervals. In addition, a handheld Omega RH31 device will be used to monitor temperature and relative humidity to ensure that contest regulations are met.