Why this distinction matters and why it is becoming more prevalent within the built environment.
As the heating, hot water and general construction industry is targeting net zero by 2050 or before, the conversation around carbon emissions - whether that be familiar terms such as whole life carbon and operational carbon emissions or newer terms such as embodied carbon reductions - is fast evolving.
The focus traditionally has been on carbon footprint, which is essentially the greenhouse gases generated during the operation of a heating or hot water system. However, increasingly the term embodied carbon is becoming more prevalent. The term and subsequent requirements is set to reveal a deeper review of the environmental impact of heat and hot water systems. This broader area must be addressed if we are to truly decarbonise buildings, infrastructure and products and therefore this terms will only grow in importance for years to come.
In this blog, we will explore the difference between embodied carbon and carbon footprint and their relevance to heating and hot water systems.
Understanding The Terms When Applied to CO2 Emissions
Carbon Footprint
The carbon footprint of a heating or hot water system refers to the total greenhouse gas emissions produced during its operation. This includes but is not limited to:
- Energy consumption
- Maintenance activities
- Emissions from fuel combustion
- Indirect emissions from electricity generation
For example, a gas-fired water heater has a higher operational carbon footprint than a heat pump powered by renewable electricity.
Embodied Carbon
On the other hand, embodied carbon refers to the carbon emissions associated with the production, transportation, installation, maintenance, and disposal of a product or system - a much more whole life carbon approach. In the context of heating and hot water, this includes:
- Raw material extraction (e.g., copper, steel, plastics)
- Manufacturing processes
- Packaging and logistics
- Installation and commissioning
- End-of-life treatment (recycling, landfill, etc.)
Embodied carbon is a one-time emission, but its impact is significant especially in systems with long life cycles or complex supply chains.
Why the Distinction Matters
1. Operational Efficiency vs Lifecycle Impact
A system may have a low operational carbon footprint but a high embodied carbon. For instance, a heat pump may run on green electricity and emit very little during use, but its construction processes could involve rare earth metals, electronics, and long-distance shipping all contributing to overall embodied carbon value.
Conversely, a gas water heater could have a high operational footprint but relatively low embodied carbon due to simpler manufacturing and shorter supply chains as an example.
2. Decarbonisation Strategies Must Be Holistic
Focusing solely on operational emissions could lead to short-sighted decisions. For example, replacing a functioning gas fired system with an electrically based system may reduce operational emissions, but the embodied carbon of the new unit and the disposal of the old one could offset those gains. Dependent on grid carbon intensity, manufacturing, system replacement requirements and additional hardware, embodied carbon can create a clearer view of the future system congruence.
A holistic approach considers both metrics, aiming for total lifecycle carbon reduction. Another important aspect here is also considering the full system i.e. cylinders, pumps and ancillaries so that the full system is clearly represented.
Embodied Carbon in Heating and Hot Water Products for Building Services
Key Contributors
- Materials: Copper, aluminium, and plastics can have fairly high embodied carbon due to energy-intensive extraction and processing.
- Manufacturing: Complex systems like heat pumps and hybrid units require precision engineering, often involving multiple global suppliers.
- Transport: International shipping and road freight add significant emissions, especially for imported components.
- Installation: On-site activities like welding, drilling, and commissioning consume energy and materials.
- End-of-Life: Systems that are difficult to recycle or contain hazardous materials (e.g., refrigerants) have higher embodied carbon.
Mitigation Strategies
- Design for longevity: Longer-lasting systems reduce the frequency of replacement and associated embodied emissions.
- Modular components: Allowing parts to be replaced rather than entire systems lowers embodied carbon.
- Local sourcing: Reducing transport distances cuts emissions.
- Recyclable materials: Choosing materials with established recycling streams helps reduce end-of-life impact.
Carbon Footprint in Heating and Hot Water Systems
Key Influencers
- Fuel type: Natural gas, LPG, and oil have high carbon footprints. Electricity from renewables has a low footprint.
- System efficiency: Condensing boilers, modulating burners, and smart controls reduce energy use.
- Usage patterns: Over-sizing systems or poor maintenance increases emissions.
- Grid carbon intensity: The carbon footprint of electric systems depends on how clean the grid is.
- System congruence and SPF: Embodied carbon assessments should be mindful of the complete operation of the heating or hot water system so that a complete understanding of all components is available.
Reduction Tactics
- Switch to renewables: Solar thermal, heat pumps, green electricity, renewable liquid fuels drastically cut operational emissions.
- Smart controls: Reduce unnecessary heating and optimise performance.
- Regular servicing: Maintains efficiency and prevents energy waste.
- User education: Encouraging responsible usage can have a big impact.
Policy and Industry Implications
Governments and industry bodies are beginning to recognise the importance of embodied carbon. In the UK, the Net Zero Carbon Buildings Framework and Part Z proposals aim to include embodied carbon in building regulations.
For manufacturers and specifiers, this means:
- Transparency: Providing Environmental Product Declarations (EPDs) for heating systems
- Innovation: Designing systems with lower embodied carbon
- Lifecycle thinking: Supporting circular economy principles
- Embodied carbon assessments / life-cycle assessment
- Sustainable materials
Conclusion: A Balanced Approach to Decarbonisation
Carbon footprint remains a vital metric, however it’s no longer enough. Embodied carbon must be part of the conversation, especially as systems become more complex.
For professionals in the heating and hot water arena, understanding both metrics enables smarter choices balancing short-term gains with long-term sustainability. Whether you're specifying a system, designing a product, or advising a client, the goal should be clear: reduce total lifecycle emissions and build a future where comfort and climate responsibility go hand in hand.
Resources
1. Part Z
2. Net Zero Carbon Buildings Framework | UKGBC
3. RINNAI PRESENTS CIBSE APPROVED CPD ON HEAT PUMP SEASONAL PERFORMANCE FACTORS :: Rinnai UK
