Active Efficiency in Action

The best way to understand the value of Active Efficiency is to see it in action. There are many examples that demonstrate the potential of Active Efficiency. Between the economic, social, and environmental benefits, the hard work that goes into making these examples successful is something to be celebrated.

Mosaic Gardens: Low-Income, Multifamily Housing Leading in the Energy Transition

Stand outside the Mosaic Gardens apartment complex in Pomona, CA, and you might think it was just like any other building on the block. But behind the palm tree landscaping and stucco-style walls is another signature California feature: the building represents leadership in clean energy innovation. The complex is the site of a collaborative project involving Active Efficiency Member Southern California Edison (SCE) and Linc Housing among other stakeholders, demonstrating how low-income, multifamily developments can integrate emerging energy technologies.

The project, which is currently undergoing its second phase, highlights how an Active Efficiency approach to building design, construction, and management can reduce energy usage and emissions while maximizing cost savings for underserved communities. Low-income families have an estimated energy burden (the percent of income spent on energy costs) of 13.9%, compared to 3% for other households, making access to high-efficiency homes even more beneficial for their economic well-being than other groups.

Components of an Active Efficiency approach

Mosaic Gardens is a three-story apartment building consisting of 46 units serving low-income tenants, with half the units dedicated to formerly homeless individuals or households. The building developer, Linc Housing, approached SCE during the design phase of the complex for support in improving building energy performance and testing new technologies to obtain Zero Net Energy (ZNE) status. ZNE status requires a building to produce as much energy as it consumes averaged over the course of a year – requiring onsite generation (a photovoltaic array in the case of Mosaic Gardens) and high-efficiency measures to ensure the energy generated onsite is enough to cover the building’s needs. Reaching this level of efficiency meant a number of both static and dynamic energy technologies needed to be installed – from top-rated insulation to digital energy monitoring. Dive into each component of the project in the dropdowns below.

Static energy efficiency measures


One high-impact element of the building envelope was closed-cell spray foam, which provides superior thermal and sound performance as well as air sealing, thanks to millions of tiny bubbles encased in the material. An added benefit of the spray foam is increased structural strength. The site served as a demonstration project for construction workers and building designers on the impact of the product both during construction and after occupancy.

Cool roof

A cool roof was installed to reflect sunlight, minimizing heat transfer to the building and reducing load on the HVAC unit.

LEDs and lighting controls

LED lights, which use 75% less energy than incandescent bulbs, were installed throughout the building, with most exterior lighting controlled by photocell.

ENERGY STAR appliances

Energy-efficient refrigerators and dishwashers were installed in all units, and efficient washing machines and dryers were installed in the community laundry room. In addition, ENERGY STAR exhaust fans were installed in the bathrooms, to meet energy code requirements for fresh air.

Mini-split heat pumps

Individual mini-split heat pumps with the highest Seasonal Energy Efficiency Ratings available at the time were installed in all 46 apartments and in two zones of the community center. The distributed nature of the heat pumps eliminates the need to shut down an entire HVAC system for repair or maintenance.

High-efficiency windows

Windows in the building exceeded building code requirements in order to improve air-sealing and enhance building performance, such as sound attenuation.

Dynamic energy efficiency measures

Smart thermostats

Each apartment has a smart thermostat, which communicate with each other in a mesh-network style configuration. Currently, the thermostats are being used to collect data on energy usage and to quickly identify maintenance issues, but in the future, they could be configured to test demand response capabilities.

Lighting controls

On top of LED lighting, Mosaic Gardens’ common areas use daylighting sensor controls to optimize the use of natural lighting.

Comprehensive monitoring

A Senseware energy monitoring system was installed throughout the complex on every electrical circuit to record electricity usage for each unit and the community center. This enables energy usage data to be collected at one-minute intervals, displayed on a dashboard in the common area so building professionals and residents have access to a wealth of information about how and when energy is being used. This also helps engage residents in learning about their building’s unique features and how they can save energy.

Battery Energy Storage System

In phase two of the project, which is currently ongoing, a Battery Energy Storage System (BESS) was installed and connected to the solar PV, primarily to improve demand response capabilities. The BESS serves as a Distributed Energy Resource (DER), allowing excess generation from the solar PV to be stored to not only improve grid reliability by providing backup power, but to reduce energy costs. Mosaic Gardens is on a time-of-use energy plan (specifically SCE’s TOU-GS-1D prime rate option), meaning that the price of energy changes throughout the day based on demand, and the BESS may be used rather than electricity from the grid when prices are high.

Each of these project components improved the energy efficiency of Mosaic Gardens. However, to meet the ambitious goal of ZNE, an Active Efficiency approach needed to be taken to make all the different components work in cohesion to maximize cost and emission savings. Active Efficiency integrates traditional/static energy efficiency measures with digital technologies to fully optimize the use of energy, and requires a more integrated, wholistic, and time-dependent perspective. This approach was fully on display at Mosaic Gardens: throughout the project, those involved viewed the complex as a “building-as-a-system,” considered the lived experiences of tenants and non-energy benefits (such as improving indoor air quality and reducing noise) that could be provided, and ensured that technology was demand response-ready as time-of-day becomes increasingly important for the cleanest, cheapest use of energy.

Real-world implications

Living demonstration projects like Mosaic Gardens are essential to understanding how low-income, multifamily housing can participate in the energy transition. Onsite, tenants are enjoying homes that are healthier, quieter, more comfortable, and more energy-efficient – helping to lower their energy burdens. But the project’s impact is not limited to within Mosaic Garden’s walls: lessons learned can help accelerate the pace of providing efficient housing for everyone, no matter their income. Those involved gained understanding of how different building components interact to improve efficiency (for example, it was discovered that the heat pumps installed could have been sized even smaller, and therefore more efficient, because of the superior building envelope improvements) and how engaging housing developers from the start of building design can save time and money on efficiency upgrades. Additionally, the importance of engaging tenants and educating them on energy-efficient practices and how to use their devices and appliances to maximize savings was a major takeaway. The project is informing the California Energy Commission’s development of new multifamily building codes for California, with the goal of reaching codes consistent with ZNE and Zero Carbon performance goal standards.

In many ways, low-income households have the most to gain from participation in the clean energy transition, and the most to lose from being left behind. Mosaic Gardens shows how emerging energy technologies can be made accessible for these households and improve their quality of life, helping to pioneer the pathway to an Active Efficiency future for all.