The future of housing is efficient, electric, and renewable. Part I: Efficient Housing
This is the first of a three part series on the future of new housing that will focus on why and how the future of housing is efficient. As world, national, state, and local leaders recognize the fact that climate change is not only caused by humans but happening right before us it’s important to focus our efforts to mitigate it on the biggest contributors to greenhouse gasses and what possible solutions exist today by sector. It’s largely accepted that buildings create roughly 40% of carbon dioxide emissions and that the operational energy (vs the embodied energy in materials) is the bulk of that 40%. Luckily, it’s possible to reduce a building’s operational energy usage on an annual basis to net zero energy with three easy steps: energy efficiency to reduce demand, electrification, and sourcing renewable energy for the remaining load. It’s also important to recognize the order in which these three steps are being presented for it to be cost effective.
President Obama once made headlines for saying “insulation is sexy” in response to a suggestion that it wasn’t from a colleague. What he meant was that the tried and true methods of air sealing and insulating old and new buildings will always be the most cost effective strategies for reducing consumption through efficiency and yet it doesn’t make for an exciting news headline or cover story. And yet by coupling smart design practices like designing for heating and cooling ductwork to be inside conditioned space (as opposed to ductwork in crawlspaces and ventilated attics) with advanced levels of insulation, air sealing, and high performance windows we can reduce a buildings annual energy consumption dramatically. In addition, these types of design and build choices lock in those energy savings for the life of the building, unlike mechanical systems, appliances, and lighting which tend to be replaced over time.
After efficient design is coupled with advanced levels of insulation, air sealing, and window performance the efficiency of the mechanical systems is the next critical step. High efficiency space heating and water heating systems have become common place even in homes built to energy efficiency state building code minimums. This is due to the fact that many code programs require that builders chose at least one option from a table of above code measures that provides additional energy savings. This mechanical system upgrade is not only easier to build in than most other options it’s easier to market to new home buyers. Even though this option is often a furnace or another type of space heating equipment, high efficiency water heating offers similar benefits of being an easier to implement efficiency upgrade that’s also easier to effectively market to new home buyers. These systems also typically provide health and safety benefits like direct vent and/or closed combustion technology that make them easier to market to health conscious buyers as well. Since space heating and water heating systems tend to be replaced over the lifetime of a home it’s worth noting that the next generation of equipment tends to offer even greater efficiencies and increased options with respect to smart systems like thermostats that learn and/or teach efficient usage behaviors and more.
After efficient mechanical systems have been selected the next major category of home energy efficiency falls on appliances and lighting. The ENERGY STAR® rating system for appliances have helped shape this market for the better and LED lighting, which offers roughly ten times more efficiency than traditional incandescent lighting, is increasingly becoming the norm.
In a category of their own are whole home mechanical ventilation systems. Airtight efficient homes are often outfitted with fresh air ventilation systems that can not only exhaust stale air and replace it with fresh, filtered, outdoor air but they can preheat the incoming cold (in the wintertime) with over 90% of the heat energy extracted from the outgoing stale air. That same system can precool incoming hot outdoor air in the summertime with stale outgoing cooler air and even provide the option of night flushing in climates that offer significantly cooler summer nights worth taking advantage of.
These types of advances in energy efficiency naturally lend themselves to healthier indoor air quality, durability, resiliency against various extreme weather events like wildfires, extreme heat and cold, and much greater comfort. These same approaches can be applied to existing homes over time and offer much of the same benefits to the occupants. In the next two installments of this series we’ll explore why and how efficiency in housing couples so well with electrification and renewable energy. By incorporating all three techniques we can reduce the energy consumption of housing to zero cost effectively.