Design of a Zero Energy Home as a first year design project

This paper describes in detail a novel, first-year, half-semester design project focused on Zero Energy Homes (ZEH's). The project has been used for three semesters and provides a relevant context for learning and applying the design process. Students apply design tools including spreadsheets, system analysis, 3D drawing, model building, research, reporting, and customer needs, all in a team-based active-learning environment. A ZEH is a high-efficiency home that is well-insulated and air-tight, oriented and designed to utilize passive solar heat, and fitted with high efficiency appliances and HVAC systems (heating, ventilating and air-conditioning). A solar thermal water heating system further reduces the energy use. The remaining use of electricity is provided by an integrated solar photovoltaic system and/or an on-site wind turbine. These homes are grid connected and sometimes draw energy from the grid; at other times they put energy into the grid such that on an annual basis, the net energy use is zero. There are several notable features of this project - most significant is that it provides the context for learning design. Students begin by using a visualization team activity for identifying the desirable features they would want in their future homes so that they realize that ZEH's provide what people want while also using zero net energy. System concepts are also emphasized by identifying and analyzing home components and their interconnections. A specially developed spreadsheet tool allows the student designers to see how design choices affect the overall energy use. Sustainability and green design concepts are introduced; students calculate their ecological footprints and research ways to reduce them. Students also learn some engineering concepts like overall heat transfer, thermal resistance, air leakage and its energy cost, and become familiar with technologies including ventilation air heat recovery, solar water heating, heat pump operation including ground-source heat pumps, passive solar heating, and solar electric systems. In the process of choosing certain components, students learn to balance first costs and operating costs, and are introduced to the concept of life cycle cost, cash flow, and financing. Google SketchUp is learned and used to create 3D virtual models of their houses. Students also construct a physical scale model of their home. Through the integration of a real world design challenge and systems thinking, students leave this project with the ability to engage in the design process, solve complex problems, and develop thoughtful solutions.