UrbanEden’s plumbing needs are met by a simple and efficient design. The mechanical room and bathroom of the house make up a “wet core” module set centrally between the kitchen and the bedroom allowing for very short plumbing runs. Therefore hot water is supplied very quickly and with limited heat loss in the fully insulated piping. Though the walls of the rest of the house are concrete, this module is framed with light gauge steel to allow for easy installation, maintenance, and updating of the plumbing system. This utilitarian layout also creates privacy by separating between public and private realms of the living space. In addition, this design allows for easy transport and set-up of the competition house as no pipes or lines related to the domestic plumbing system cross into adjacent pods, therefore the system can be completely installed before delivery to the competition site.
Given the continuing decline in price and simultaneous climb in conversion efficiency of photovoltaic panels and the low relative cost of electricity in North Carolina, a cost-benefit analysis ultimately led the engineering to team decide against implementation of a solar thermal array for water heating purposes. Instead, the roof space typically held by a solar thermal array contains additional photovoltaic panels whose energy is used to power an efficient electric heat-pump water heater.
The cornerstone of UrbanEden’s domestic plumbing system is a hybrid electric heat-pump water heater generously donated to the project by the Vaughn Thermal Corporation. The S50WHPT3838I unit from Vaughn has the capacity to heat 50 gallons of potable water using either an air-to-water heat pump, or a resistance-heating element. These elements operate simultaneously and separately based on the conditions and demand requirements. Optimization of energy consumption and assurance of demand satisfaction is made possible by a multi-mode controller onboard the tank, which can be manipulated either directly or remotely by the home’s occupants. In addition, the tank of the heater incorporates Vaughn’s proprietary Hydrastone™ lining, a one-half inch-thick stone lining that insulates and prevents tank failure due to corrosion.