We tend to focus on energy consumption when discussing greenhouse gas (GHG) emissions in buildings, and for good reason. Lighting systems, heating, and air conditioning are often the most visible contributors.

But there’s a lot more going on beneath the surface. Buildings are full of lesser-known culprits that quietly contribute to emissions: refrigerants, embodied carbon in materials, and operational inefficiencies, to name a few. These overlooked sources can have a surprisingly large impact on a building’s carbon footprint and reining them in is a critical step in moving toward a genuinely sustainable space. 

The Power of Refrigerants 

Building cooling and refrigeration systems don’t usually command much attention unless they stop working on a sweltering summer day. However, many of the most common refrigerants, including the hydrofluorocarbons (HFCs) that power many commercial air conditioning and refrigeration units, have a global warming potential (GWP) thousands of times higher than carbon dioxide (CO₂). This means each refrigerant molecule contributes thousands of times more to climate change than a carbon dioxide molecule.

As a result, when these refrigerants leak or are disposed of, they are a significant climate risk and source of building-level greenhouse gas emissions. If left unaddressed, even minor leaks can add up to a substantial climate impact over time. 

Regulations are increasingly steering the industry away from HFCs. In the U.S., the AIM Act mandates an 85% phasedown of production and consumption by 2036, aligning with global efforts like the Kigali Amendment. Canada, Europe, and certain U.S. states also have stricter rules on high-GWP refrigerants. The AIM Act is already impacting HVAC use in buildings: As of January 1, 2025, it is no longer legal to manufacture HVAC units with certain refrigerants and no existing-to-be installed units can be installed after January 1, 2026. 

Proactively adopting lower-GWP options such as the new A2L hydrofluoroolefins (HFOs) or natural refrigerants like ammonia (NH₃) and carbon dioxide (R-744) can future-proof buildings and cut emissions. Proper maintenance, leak detection, and responsible disposal (recovering rather than venting refrigerants) are equally vital. By staying ahead of regulations, building owners can reduce risks, lower their carbon footprints, and avoid costly retrofits. 

Embodied Carbon in Building Materials 

Beyond cooling systems, another significant source of overlooked emissions is within the materials used to construct buildings. This embodied carbon is baked in from the beginning of the building’s life, or whenever the product was installed. It accounts for the emissions generated during the extraction, processing, transportation, and installation of building materials.

This embodied carbon typically accounts for around 15% of a building’s total emissions. It’s easy to see where this comes from when you look at common building materials. For example, cement production alone is responsible for about 8% of global CO₂ emissions.

Recognizing the magnitude of embodied carbon opens the door to more thoughtful material choices and design strategies. For example, cross-laminated timber (CLT) harvested from responsibly managed forests can replace steel in some structural applications, acting as a carbon sink rather than an emitting source. Low-carbon concrete mixes that rely on supplementary cementitious materials like fly ash can also help further reduce emissions tied to traditional cement.  

On the due diligence side, lifecycle assessments (LCAs) help weigh the pros and cons of different material options, while Environmental Product Declarations (EPDs) offer transparency into a product’s total climate impact. By selecting materials that minimize embodied carbon, it becomes possible to shrink the lifetime carbon footprint of a building, sometimes more substantially than even the best operational improvements. The Carbon Leadership Fund is a great resource for owners, developers, and the AEC community looking to learn more about ways to reduce embodied carbon in building materials.

Operational Inefficiencies 

Even after construction is complete, day-to-day operational inefficiencies can quietly build up in terms of both cost and emissions. The U.S. Department of Energy estimates that the average commercial building wastes around 30% of the energy it consumes. Poorly maintained HVAC systems frequently top the list of culprits. Dirty filters, broken dampers, and outdated controls can force systems to use significantly more energy than necessary.  

Lighting also plays a role. Despite the widespread availability of LEDs and other energy-efficient solutions, many offices still rely on outdated fixtures that waste electricity and generate unnecessary heat. Meanwhile, water heating is often overlooked as a major drain. Inefficient boilers or water heaters that never “sleep” when hot water demand is low can consume enormous amounts of energy, particularly in large facilities. 

Building automation systems (BAS) and other Prop Tech solutions are excellent tools for nipping these inefficiencies in the bud. Building automation systems (BAS) can track real-time energy usage for HVAC, lighting, and water heating, identifying anomalies like lights left on in empty rooms or HVAC systems that cycle too often in unoccupied areas. This continuous monitoring and remote control saves energy and lowers operational costs. However, reaping these benefits typically requires a proactive mindset. A sustainable facility management plan laying out regularly scheduled maintenance and re-commissioning keeps everything running at peak performance instead of gradually slipping into expensive, carbon-intensive waste. 

Other Overlooked Emission Sources 

Plug Loads & Phantom Energy 

Electronics and appliances draw a surprising amount of power when they’re not in use. Known as phantom energy use or standby power, this trickle consumption adds up, especially in large office buildings that house hundreds of computers, monitors, and chargers.  

The National Renewable Energy Laboratory has noted that plug and process loads can account for up to 50% of total energy consumption in a commercial building. Simple strategies like employing smart power strips that cut power to devices when they’re idle, or selecting ENERGY STAR-rated equipment, can reduce this constant pull on the grid. 

Transportation-Related Emissions 

Even how people and goods move to and from your building affects its carbon footprint. While transportation-related emissions are often categorized separately, location and design choices can significantly influence commuting patterns and shipping logistics. For example, providing electric vehicle (EV) charging stations can encourage a cleaner commuting culture. Likewise, designing or retrofitting loading and unloading zones to minimize vehicle idling contributes to fewer greenhouse gas releases in the immediate area. 

Waste Management 

No conversation about hidden emissions is complete without addressing waste management. Landfills are a major source of methane, which has a GWP 27 times greater than carbon dioxide. Food scraps, yard waste, and other organic materials release methane when they decompose anaerobically in a landfill. Meanwhile, construction and demolition debris can lead to wasteful practices that further drive up embodied carbon for new materials. Implementing recycling programs, investing in on-site composting (where feasible), and exploring deconstruction rather than demolition can all reduce a building’s waste-related climate impacts. 

Strategies for Mitigating Hidden Emissions 

So, how do businesses begin to chip away at the less obvious but still impactful sources of building emissions? 

1. Conduct Regular Audits: Comprehensive waste and energy audits help you pinpoint exactly where your building is releasing GHGs. Don’t forget refrigerant leak checks in these assessments. 
   
   
2. Transition to Sustainable Materials & Systems: Whether you’re constructing a new facility or retrofitting an old one, opt for materials with low embodied carbon and HVAC systems using low-GWP refrigerants. 
   
   
3. Embrace Smart Building Technologies: Automation systems, sensor networks, and IoT devices can continuously monitor performance and flag inefficiencies in real-time. 
   
   
4. Partner with Sustainability Consultants: Working with a specialized team like Emerald Built Environments helps you develop a robust, end-to-end emissions reduction plan. From material selection to operational best practices and waste diversion strategies, professional guidance can save you both time and money in the long run. 

No Emission Left Behind: Creating Sustainable Buildings 

While lighting and HVAC energy demand remain central to discussions about building-related GHG emissions, many overlooked factors are just as critical. By proactively identifying and tackling these hidden sources, building owners can shrink their carbon footprints without compromising occupant comfort. The benefits aren’t purely environmental: lower utility bills, enhanced occupant well-being, and an enhanced reputation often follow. 

Bringing in a consultant team like Emerald Built Environments, A Crete United Company, to help guide choices and implement effective solutions can streamline the process. Addressing the full spectrum of hidden emissions is essential for creating truly sustainable buildings and ready for the future.