The word “sustainable” in real estate is overused. However, when homeowners Gus Anning and Sarah Rowe began exploring how to build a home for themselves and their three children, they really dug deep — literally and figuratively — for a building type that was genuinely self-sufficient for energy, water and waste. After three years of research, two years of planning and nine months of building, their home — dubbed Te Timatanga, or “beginning” in Te Reo, one of New Zealand’s official languages — was unveiled to viewers in the first New Zealand season of the television show Grand Designs.