Power-Efficient Design Strategies for Small Multifamily Buildings
As San Francisco, the Bay Area, and California continue the push to reduce climate pollution, electrifying buildings—especially small multifamily residences—has become a key strategy. However, the transition from gas to electric appliances often raises concerns about increased bills and the need for costly electrical panel upgrades. This article explores the benefits of power-efficient design strategies to address both concerns while improving the air quality and comfort of the City’s building stock.
The Gas-to-Electric Dilemma
The shift from gas to electric appliances is often assumed to require a panel upgrade. This assumption stems from the fact that many electric appliances—especially traditional models with resistance coils—demand more power than older gas systems. For example, switching from a gas stove or dryer to a conventional electric range requires a 240V connection, which older buildings may not support due to limited panel size. The SF Environment Department estimates that multifamily buildings generally need about 60 amps per unit to comfortably electrify a multifamily building (a single-family home generally requires a 100-amp panel, for comparison).
Upgrading electrical panels and service capacity is a significant barrier to electrification. These upgrades can cost thousands of dollars, involve long wait times for utility coordination, and require complex permitting. For small multifamily buildings, which often operate on tight budgets and limited space, these upgrades can be prohibitive.
Power-Efficient Design: Doing More with Less
This is where power-efficient design comes in. By reducing the overall electrical load, buildings can avoid these costly upgrades when transitioning to clean electric systems.
Doing More with Less
Power-efficient design is a strategic approach to electrification that focuses on minimizing energy demand. Also known as the Watt Diet, this philosophy encourages building owners to “slim down” their electrical consumption by choosing appliances and systems that use less power. It’s not about sacrificing comfort or functionality—it’s about making smarter choices.
Rather than simply replacing gas appliances with high-powered electric ones, this strategy emphasizes:
- Optimizing load calculations to reflect actual, rather than worst-case, demand
- Choosing efficient, right-sized equipment to reduce the demand for electricity
- Monitoring and controlling high-load operations to stay within capacity limits
Silicon Valley Clean Energy has created an excellent flyer explaining each of these strategies. Let’s look at each of them in turn.
Optimizing Load Calculations
The standard way to determine the electric demand of a building is to simply add up the individual electric loads of all appliances and electric equipment. This can be seen in the load calculation on the left. In reality, however, it is the rare building that runs all loads at maximum power at the same time.
For this reason, the State of California allows electricians to use an alternate calculation method based on actual demand over the past year. As can be seen on the right, the same building actually has plenty of available electric capacity to add power-consuming appliances. To minimize electrical work, it is therefore essential to find an electrician who is familiar with this alternative calculation.
Choosing Efficient, Right-Sized Equipment
In recent years, manufacturers have come out with several innovative 120V appliances that support power-efficient design. These technologies are ideal for retrofitting small multifamily buildings while reducing the likelihood of a panel upgrade.
1. 120V Induction Cooking
Induction cooktops are a cornerstone of efficient electric cooking. Unlike traditional electric stoves, which rely on resistive heating, induction cooktops use electromagnetic fields to heat cookware directly.
2. 120V Heat Pumps
Heating and cooling systems are major energy consumers. Traditional HVAC systems generally require 240V connections, but 120V heat pumps offer a low-power alternative.
Advantages:
- Comfort: Heat pumps heat and cool in one device and maintain consistent temperatures
- Bill savings: Heat pumps are 3-5x as efficient as other heating systems.
- Lower power draw: 120V units operate on a standard circuit.
These systems come in a variety of form factors, making them ideal for the variety of multifamily buildings in San Francisco.
3. 120V Heat Pump Water Heaters
Water heating is another significant energy load. 120V heat pump water heaters use ambient air to heat water, dramatically reducing electricity use compared to standard electric options.
4. 120V Heat Pump Washers and Washers
Laundry appliances are often overlooked in electrification plans, yet they can be major energy users. 120V heat pump dryers and washers offer a low-power solution that aligns with the Watt Diet approach.
By choosing equipment carefully, a property owner can dramatically reduce the power requirements of an electrification upgrade:
Monitoring and Controlling High-Load Operations
Power-efficient electrification is not just about choosing the right appliances—it’s also about understanding how they interact with each other and the building’s electrical system.
Design strategies that help to keep electricity demand under control include:
- Staggering appliance usage to avoid peak loads
- Using smart panels or load management systems to share power between devices
- Selecting two-in-one appliances that do two jobs on one circuit
For example, circuit-sharing devices allow you to run a dryer and EV charger on one circuit. Similarly, larger and more powerful washer-dryer combos save space in your laundry room as well as your panel.
Electrification Without Overload
Electrifying small multifamily buildings is essential for reducing greenhouse gas emissions and improving indoor air quality. However, the perceived need for electrical panel upgrades can be a major deterrent. The power-efficient design strategies outlined here offer a practical alternative for avoiding the worst of these upgrades. With thoughtful design and the right technologies, electrification can become feasible in San Francisco’s diverse multifamily housing stock and improve the quality of life for tenants across the City.
An essential first step to electrifying your building is to arm yourself with as much information as possible. To assist small property owners in the process, the SF Environment Department maintains a list of electrification advisors that are familiar with power-efficient design and the new products currently available. Their role is to work with property owners on customized electrification plans, navigating incentives and rebates, and providing guidance on equipment and rates. Visit betterelectric.org for a list of firms and many other resources around building electrification.