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Dog Day Afternoons

Dog Park’s Solar- powered Restroom Goes Off-grid

By John Mesenbrink W The

hen Heritage Park, a 1,238-acre park located in Johnson County, (Olathe), Kansas, needed to go a little “off-grid,” a top-notch solar photovolta-

ic (PV), hot water and radiant floor system — a complete solar-powered restroom facility — was the answer. In par- ticular, the off-leash dog park needed an oasis of the human kind. To accommodate the 200-plus person per day traffic, a state-of-the-art, off-grid restroom was designed, built and is now in full working order. This 30-acre, fenced open space park with a small pond is a playland for hundreds of canines — and happy humans — to roam free.

Architect Berger Devine Yaeger (BDY), who spec’d the

system, was approached by the Johnson County Parks District to design a simple restroom structure in the dog park that could be used year-round. Because of its loca- tion, off-grid was chosen for energy design. The building features both solar thermal and solar PV systems to facil- itate the off-grid application. This simple restroom became a cost-efficient, energy efficient, green building by utilizing the following: • Photovoltaic source of electrical power; • In-slab radiant heat with rooftop solar vacuum heating

tubes; • Passive solar heating by the use of a Trombe wall; • Indirect lighting through the use of clearstory win-

dows; • Durable cfmu insulated masonry wall construction;

and • Structurally-insulated roof panels. The contractor for the solar thermal job was Bob Dolan,

owner, BMK Plumbing & Solar of the Midwest, who won the contract to install waste, vents, water, radiant floor heating, solar thermal and solar PV. The solar thermal system consists of 120 Viessmann

Vitosol-300 evacuated tubes supplied to BMK Plumbing from Metropolitan Industries, Romeoville, Ill. There are a total of four, 30-tube manifolds. The solar thermal tubes are used for heating the floor, which, of course, has radi- ant tubing installed in it.

Page 38/Plumbing Engineer

Vi tosol 300-T high p e r f o rma n c e vacuum tube collector operates according to the proven heat pipe principle. It offers particularly high oper- ational reliability. One of the specific applications of the Vitosol 300-T is in systems with long phases of high solar irradiation without heat transfer (so called stagnation phases). The dry connection of the heat pipe tubes inside the header and the integral temperature limiter ensure par- ticularly high operational reliability. In heat pipe systems, the solar medium does not flow

directly through the collector tube. Instead, a process medium, which circulates in the copper pipe below the absorber, evaporates when subjected to solar irradiation and transfers the heat to the solar medium via a heat exchanger. The condensers are completely surrounded by patented

Duotec twin-pipe heat exchangers. This absorbs the heat particularly well and passes it into the heat transfer medi- um flowing past it. Also, a temperature limiter integrated into the Vitosol 300-T protects the system against over- heating during longer idle periods. The system also used a Viessmann Divicon pumping

station and a solar controller. The hot water storage tank is a 400-gallon solar tank custom-built by Metropolitan Industries and has double coils for transferring heat from the solar system to the radiant floor system. The tank is well insulated with 3" foam on the top and 2" on the sides. A 150-gallon propane tank was used as a back-up heat-

ing source. The solar PV system — consisting of solar modules that

convert the sun’s energy into electricity — is made up of 20 Suntech 175-watt PV panels, supplied by Conergy, which charge 24 batteries. Conergy selects the best solar modules in the industry, including selections from BP, Sanyo and GE. The DC power in the batteries is convert-

Continued on page 40 April 2011

The energy efficient green building features a photovoltaic source of electrical power and in-slab radiant heat, with rooftop solar vacuum heating tubes.

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