Building retrofits: Innovation pathways to a more efficient built environment

Author: Roberto Interiano and Diana Fisler

In February 2021, winter storm Uri brought record low temperatures, ice, and snow, devastating unsuspecting regions of the U.S. like Texas. Only a few months before, much of the U.S. endured a rare and extremely active 2020 hurricane season. These recent events, compounded by projections of future weather events, remind us that climate change delivers unpredictable blows.

To mitigate the dangerous situations and expensive repairs brought by weather hazards, we rely on extensive and regionally customizable building codes. These codes often respond to disasters by tightening requirements for new buildings’ resistance to flood, fire, and wind. Focusing on new construction, however, does not account for the huge number of vulnerable buildings that already exist. The state of our building stock demands attention to ensure not just safety and resilience but also comfort and energy efficiency. Air-tight and well-insulated homes can better withstand extended power outages and extreme weather while reducing energy costs and increasing comfort even during pleasant weather.

Why retrofit?

Approximately half of America’s homes and commercial buildings were constructed over 40 years ago—before the existence of many of today’s building equipment standards, efficient products, and codes. Various structures completed before 1980 – totaling 46 billion square feet – are ripe for energy-efficiency retrofit and represent a significant opportunity to unlock energy savings through building envelope improvements.

Today’s efforts

There are dozens of private and public, large and small organizations developing and implementing approaches to facilitate building retrofits. To help address the opportunity, in 2019 the Department of Energy launched the Advanced Building Construction (ABC) Initiative to accelerate deep energy retrofits by investing in and guiding advanced technologies. More recently, the Biden Administration plans to support upgrades of 4 million buildings and weatherizations of 2 million homes over four years – a very decisive call to action for building efficiency businesses across the US.

What’s out there?

Building retrofits can include changes to lighting, space heating and cooling, insulation, and air sealing for surfaces (ceilings and walls) and openings (doors and windows). Accommodating these complex, often interacting systems requires both expert knowledge and a careful and thoughtful approach. Lately, more innovation has focused on facilitating the retrofitting process through less invasive, less expensive, and more efficient technologies and high-performance building materials and procedures. Here, we walk through a few examples of major retrofit project categories.

Lighting

Retrofit choices differ in degrees of invasiveness and commitment. Lighting renovations are relatively simple, consisting of replacing old lighting fixtures with options that save energy and have less embodied carbon and waste. Sometimes, lighting retrofits can also involve relocating fixtures to better leverage natural lighting.

HVAC

Space heating and cooling retrofits focus on implementing more energy-efficient ways of maintaining a safe and habitable indoor environment. These procedures are usually more invasive, comprising sealing and insulating ducts, switching out HVAC components for newer technologies, using sensors to direct and optimize heating and cooling, and in some cases even upgrading to more emissions-friendly fuel choices like geothermal. These changes are making more and more economic sense as existing heating and cooling systems reach end of life.

Airtightness

Moving to the building envelope, insulation and air sealing measures limit the energy required to maintain temperature differences by limiting heat flow from the conditioned and unconditioned building environments. These efforts can range in complexity, from simply upgrading attic insulation, to “drill and fill” of existing walls without removing the cladding, all the way to a whole-house deep energy retrofit which might require recladding the whole exterior wall structure.

Of special interest is finding less invasive ways to accomplish these treatments. One clever example, Aeroseal’s Aerobarrier, helps seal non-visible air leaks and reduce mechanical loads to promote healthier air quality while minimizing project duration and disruption to occupants.

Retrofit robots

Beyond the solutions mentioned above, developing advanced robotics for building envelope retrofits is an enabler that allows workers to reach places that are otherwise unsafe or difficult to access while facilitating quality and consistency – not to mention safety – when installing energy efficiency measures. Advanced robotic solutions may seem futuristic, but they are here today.

One example, Q-bot, is a robotic solution for insulating floors from beneath by accessing the crawl-space found in many older homes and buildings. To date, the company has developed a handful of agile, tethered robots that infiltrate hard-to-reach places and employ artificial intelligence (AI) to identify and non-invasively apply insulation. The construction-inspection assistant designed by Boston Dynamics, Spot, is another robotic solution designed to tackle the challenges faced in the built environment: as Spot ventures a construction site, it inspects progress, creates a digital model, and compares site conditions with technical drawings.

E-ROBOT Prize

To encourage further robotic innovation to drive energy efficiency in envelope retrofit solutions, the National Renewable Energy Laboratory (NREL) recently launched the American-Made E-ROBOT Prize. In alignment with the ABC Initiative, the prize focuses on developing advanced robotics to meet critical needs and reduce barriers in building envelope retrofits.

ADL Ventures is a power connector of the Department of Energy’s American Made Network and would love to hear your retrofit ideas and/or questions about the E-ROBOT Prize.