Decarbonizing Heat in the Built Environment

With the climate crisis intensifying, the decarbonization of heat in buildings has emerged as a significant yet unmet challenge. Globally, heating accounts for nearly half of energy consumption in the built environment. The direct carbon emissions resulting from burning fossil fuels for space heating, water heating, and cooking makes up a significant portion of overall emissions.

Keeping homes warm and providing hot water are essential services worldwide. Around 40% of households require space heating during part of the year, making it a major home energy cost, especially in colder regions.

In 2022, building operations accounted for 26% of global energy-related emissions, with the sector’s energy use rising by about 1% versus the prior year. Of buildings’ contribution, 18% were direct emissions from on-site burning of fossil fuels for heat and 8% were indirect emissions from purchased electricity and heat.

With the imperative clear for all industries to rapidly reduce emissions amid the climate emergency, the built environment sector, especially the decarbonization of heating, lags other important sectors. As all industries take steps to decarbonize amid the climate emergency, innovative solutions and policies are urgently required to align low-carbon building heating with global climate goals.

Boilers and Beyond: Charting Site-Specific Routes to Low-Carbon Thermal Comfort

Most buildings still depend on fossil fuel-based heating systems, especially gas boilers. Per a study conducted by Global Market Insight, over 25 million units were acquired in 2022 as predominant solutions for water and space heating in residential and commercial properties.

Achieving net zero emissions requires a deep retrofitting of existing real estate assets on a case-by-case basis to transition from conventional to modern heating technologies. New buildings have an advantage in enabling more ambitious sustainability targets through construction specifications. However, the true test lies in cost-effectively upgrading existing infrastructure locked into carbon-intensive energy supplies.

With older properties, decarbonization feasibility depends on site-specific conditions and opportunities. Blanket solutions fail to address unique constraints. Navigating decarbonization pathways relies on tailored engineering assessments of current systems – their limitations and capabilities to support greener alternatives. Building-level customization grounded in technical realities, not just lofty aspirations, illuminates practical routes to decarbonization.

What is a Zero Carbon (Operational) Building?

The pathway to achieving a net zero carbon building is highlighted under the UK Green Building Council’s 2019 Net Zero Carbon Framework, which involves the eradication of Scope 1 (direct) emissions. Utilizing highly efficient, often electric-powered heating and hot water systems like air and ground source heat pumps is one way to trim emissions from traditional fossil fuels burning systems. With no on-site fossil fuel combustion, Scope 1 emissions can be eliminated. Purchasing renewable energy, generating energy on-site, or participating in carbon offset schemes mitigates the remaining Scope 2 emissions from electricity usage. While critical, focusing solely on existing thermal energy systems is insufficient – a holistic and considered approach is essential to proposing intervention strategies that are both effective and complement each other. For example, seeking opportunities to enhance building envelopes, glazing and existing building services can provide significant opportunities to trim emissions. As space and water heating comprise the largest portion of emissions for most buildings, transitioning these thermal loads to zero-carbon is especially impactful.

For existing non-domestic buildings, numerous retrofit challenges exist. However, significant emissions reductions can be achieved by electrifying and enhancing efficiency across the current inefficient building stock. Fuel switching, BMS/controls upgrades, and insulation uplifts are examples of key decarbonization levers. Their relative importance e.g., carbon reduction potential vs relative expenditure varies depending on factors like building age, climate, and the associated embodied carbon of new materials. Overall, innovating to provide low-carbon heating and hot water in both new and old real estate assets is essential to meeting net zero goals.

A Holistic and Tailored Approach to Decarbonize Existing Non-Domestic Buildings

Decarbonizing existing buildings requires a tailored approach, assessing each property’s unique characteristics. At Terra Instinct we utilize an effective framework that can be applied to any of the 2.1M (2022) non-domestic buildings in the UK, and beyond:

1. Use less energy: Reduce the demands and prioritize passive measures like insulation, air sealing, and modern glazing.
2. Use energy efficiently: Review and enhance system performance e.g., Maximize the efficiency of heating, cooling, lighting, and ventilation systems. Review the efficacy of existing control systems and review thermal insulation extent for existing distribution services.
3. Reduce reliance on fossil fuels e.g., low and zero-carbon thermal energy systems, district heating, hybrid thermal energy systems to transition from fossil fuels and avoid stranded assets, and electric cooking equipment. 
4. Use renewable energy. e.g., procure 100% renewable electricity, on-site zero-carbon power generation, and consider energy storage.
5. Install monitoring systems to optimize and track performance and periodically verify emission reductions.

The Imperative and Challenges of Decarbonizing Heat in Buildings

Decarbonizing heating systems across the UK and global building stock presents a monumental challenge. The sector remains heavily dependent on fossil fuel solutions like natural gas and oil boilers that are deeply entrenched across residential, commercial, and industrial real estate. Transitioning away from these carbon-intensive technologies is complex given the diversity of building types, regions and technical barriers. Moreover, retrofitting existing properties requires distinct strategies versus ensuring new constructions are net zero compatible. The substantial capital costs of enabling zero-emission thermal energy for buildings are also proving prohibitive.

To meet climate goals, transformative change is clearly needed. However, this transition faces key obstacles that require collaborative solutions:

• Improving Energy Efficiency & Standards – Regulatory environments vary, slowing the adoption of optimal standards. Developing nations also face economic and technological limitations.

• Retrofitting Existing Buildings – Upgrades pose financial, logistical, and technical hurdles for owners. Integrating modern systems into outdated buildings adds complexity.

• Enhancing operative skills and training- The UK government has stipulated the requirements for heat pumps sales to rise from 30,000 to 600,000 in the next five years. Diverse, rapidly evolving operative skills are required to meet the nuanced demand of net zero. A lack of expertise, access, and awareness persists.

• Infrastructure Transitioning to low-carbon heating demands infrastructure upgrades, including shifts in pipeline systems and increased focus on electrification. Retrofitting existing buildings for new heating systems poses logistical and cost challenges.

• Electricity Grid Readiness – Surging heat pump use risks overburdening grids. Low-carbon capacity, demand management, and modernization provide resilience.

While the barriers are immense, targeted strategies focused on efficiency, infrastructure, training, regulations, and technology can chart a path to decarbonization. With collaboration and innovation, the transformation of building heat to meet climate goals is within reach.

Plotting Multiple Solution Pathways Toward Carbon-Neutral Heat for Buildings

There are several emerging trends offering solutions to pathways towards a zero-carbon future for heating buildings:

• Advanced heat pumps show promise as electric heating alternatives if efficiency and output temperatures can be increased via enhanced refrigerant performance and multi-stage configurations. However, feasibility concerns persist around costs and scalability.

• Hydrogen’s role in buildings spurs debate given infrastructure barriers, unproven readiness, and electric alternatives. Blending hydrogen with methane raises operations and continued carbon emissions issues. While green hydrogen from electrolysis is possible, it is as yet unproven on a large scale.

• Micro-CHP systems, fueled by gas, LPG, oil, or bio-liquids, are considered low-carbon due to their enhanced efficiency compared to traditional heating methods. Resembling standard boilers, they can simultaneously generate electricity and heat water, a feature absent in traditional combi boilers.

• Improving building optimization energy efficiency through insulation, advanced controls, and tailored designs complements the transition to low-carbon heating. Many buildings, not initially designed for current needs, require modifications for enhanced energy efficiency. Key considerations include tailored design compliance, understanding implemented technologies, routine building health evaluations, and addressing energy wastage. Machine learning-driven models predict occupancy patterns, optimizing building systems and achieving substantial energy savings. This optimization is crucial for successfully decarbonizing existing buildings.

Overall, pursuing research, pilot projects, supportive policies, and upgrades systemwide are key to transforming the carbon intensity of meeting building heating demands. A diversity of solutions and collaborative action are required to chart pathways toward fossil fuel-free thermal systems.

Towards a Decarbonized Future

The decarbonization of heat in buildings is an urgent climate imperative. Achieving this requires a multifaceted approach addressing infrastructure, costs, technology, retrofits, and public engagement. Strategic investments and innovations in these areas can accelerate the transition away from carbon-intensive heating dependency.

Fostering consumer awareness and community-based initiatives is essential to drive adoption of low-carbon solutions. However, systemic transformation also hinges on upgrading distribution systems, enhancing building efficiency, deploying emerging technologies, and incentivizing widespread change.

With a holistic strategy focused on equipment, infrastructure, finance, regulation, and public outreach, a zero-carbon future for building heating is within reach. Concerted efforts to reimagine thermal provision can lead the way to deep decarbonization.