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This post will make the case for why ADU developers should ditch natural gas, and go all electric.
Natural Gas, or methane has been promoted both as a ‘Clean Fuel’ or a ‘Bridge Fuel’ in various circles, both locally and nationally during this time of climate crisis. Concurrently, the IPCC has called for a far more rapid decline in the use of fossil fuel, more rapid scaling up of renewable energy taking advantage of the falling costs, and avoiding a lock-in of high-carbon infrastructure.
Buildings generate nearly 40% of annual global GHG emissions in the U.S. In order to meet our climate goals, we need to move beyond the burning of fossil fuels, including the use of Natural Gas. Burning gas is now a bigger source of climate-altering emissions than burning coal, and nearly a third of that gas is burned in homes and commercial buildings.
ADUs present an especially easy opportunity to cut the gas line and go all electric due in part to their small size and low heating and cooling demands. This coupled with the cost savings of not having to install a gas line from either the street or the main home makes ADUs a great candidate for an easy transition to all-electric building. All-electric buildings are the easiest path towards a net zero carbon built environment when the electric usage is offset with renewables, usually solar photovoltaic in the case of ADUs.
It turns out that cutting the ‘Gas Line’ can be a win-win scenario in an ADU. There are a myriad of negative aspects of burning gas that can be avoided by switching to all electric buildings. Issues such as methane leaks, groundwater pollution from fracking, pipelines through native lands, forests, rivers and ecologically sensitive areas, earthquake risks, explosions, increased fire risk, dangerous indoor air quality, bad public policy and negative health risks can all be avoided.
By avoiding Natural Gas we can also have ADUs with much better energy efficiency, lower energy bills, higher indoor air quality, less risk of fire, higher comfort and better performance. We should advocate for ADUs that are longer-lasting and more resilient and responsive than those that rely upon fossil fuels.
Of course, designing and building an all electric ADU can have its challenges– economic, architectural and behavioral. These issues can be mitigated with smart systems choices, energy efficiency savings, and educating one’s self or one’s clients ahead of time about the slightly different ways that living in an all electric ADU presents.
From an economic standpoint, heat pumps for heating/cooling and water heating, LED lighting, and induction ranges can potentially add a premium to the already constrained budget. This should be tempered with the cost savings of the improved energy efficiency of these systems over time. Heat pumps can be up to 250% more efficient (and up to 500% more efficient in some water heating applications) relative to the combustion of natural gas, thus saving money and impacting cash flow positively from day one. This can be especially impactful if the ADU is intended to be a rental as one can ‘include’ these utility costs to the tenant. The tenant, even if paying typical utility fees, will be able to take advantage of the higher indoor air quality, better comfort, and other benefits of going all electric, so there is a qualitative positive value for the tenant. Additionally, it typically costs between $1,500 – $2,000 to install a gas line— or more if the gas meter has to be upgraded— to the ADU. These initial savings can be put towards these other systems and can temper the upfront costs of upgrading to all electric.
But, I Like Cooking on a Gas Range….
The main behavioral change of going all electric is letting go of the gas cooktop. This is likely the biggest hurdle to removing gas from an ADU. As opposed to the old electric resistance cooktops that took forever to warm up then turned uncontrollably red hot, induction ranges can perform just as well as gas cooktops, and address a number of typical concerns voiced about this issue. Induction ranges use magnetic induction to heat the pan itself and are extremely responsive and precise when adjusting temperatures. Since they don’t heat up the surface of the cooktop, they reduce the potential for burns and are safer than electric or gas cooktops. They are also powerful, being able to boil a pot of water in an astonishingly short time, while also sensitive enough to sauté delicate sauces without overheating or burning. Granted, charring the peppers or some wok cooking may be out of the question, but a few minor behavioral changes or an outdoor grill may have to suffice.
Another issue with gas cooking is the associated indoor air quality issues that arise through combustion during cooking. Gases such as nitrous dioxide, carbon monoxide, formaldehyde, mercury, methane and particulates are produced when burning natural gas. These gases and particulates have been associated with negative health effects such as respiratory disease, chronic respiratory illness in children, decreased pulmonary function, depression, cancer, nervous system disorders, birth defects and organ damage, among others. An induction range does not combust anything, therefore bypassing a lot of these gases. As always, it is a good idea to have a vent hood with a large capture efficiency that includes make up air and is vented directly to the outside to capture any cooking particulates.
Switching to an electric heat pump hot water heater can present challenges, especially when the ‘on demand’ gas hot water heaters can traditionally be used as a space saving approach in ADU design. Typically, the combination heat pump hot water heater is fairly large, at about 5’ tall for the smaller units. These units require a certain amount of clear space around them to meet their venting requirements. Additionally, they can dump cold air into the surrounding conditioned space which should be avoided, if possible. One solution is to order a venting kit that can be used to vent the units to the outside, thus avoiding some of these issues. In order to do so, the unit should be located near an exterior wall, which has the potential to further complicate design. There are newer split hot water heaters such as the Sanden system which are much smaller and extremely efficient— topping out at a whopping 500% efficiency. These work really well in the ADU vernacular as they can be located much easier as they don’t need to be near an exterior wall and are only 4’ tall. They also behave as a much larger unit since they hold the water at a higher temperature, so there is little worry of ever running out of hot water. The downside is the higher cost, but they will pay for themselves over time and do allow for a much less constrained design.
Going all in on the all electric ADU shouldn’t be too much of a stretch in our market (Portland, OR). Our company, Birdsmouth Design Build, has been producing all electric ADUs for going on 8 years now without complications or complaints from our clients— in fact it has been the opposite experience with clients commenting on how comfortable these ADUs are and proudly showing off their very low electric bills. Additionally, there are a number of jurisdictions across the country that have implemented a ban on natural gas in new construction or are otherwise considering doing so. Cities such as Berkeley, CA have passed bans and others in northern California have followed suit. Recently Santa Monica and other cities in Massachusetts, Oregon and Washington have started contemplating changes to their codes.
To continue building with Natural Gas as one of our main sources of fuel is locking ourselves into decades of carbon emitting infrastructure, stranded assets and reduced flexibility in future response options. There are mostly upsides to getting rid of Natural Gas in our ADUs. The natural gas industry would like to make you think otherwise (‘Balanced Energy Solutions’), but the goal of this post is to get people to take an objective look and consider the risks of using Natural Gas vs. the rewards of switching to an all electric ADU.
By Joshua Salinger, Founder and CEO of Birdsmouth Design | Build