Why do we need to cut emissions from HVAC quickly?

While other disciplines have reduced their fixed emissions, HVAC has stood still. This has contributed to HVAC now having one of the largest climate footprints in buildings.

HVAC is usually not included

Greenhouse gas calculations for construction projects have in recent years become a common and important part of projects' monitoring of their environmental and climate footprint. Since the introduction of NS 3720 Method for greenhouse gas calculations for buildings (2018), the industry has had a unified method for calculating greenhouse gas emissions throughout the life cycle of buildings. This has led to increasing knowledge, especially about fixed emissions associated with the production, transport and replacement of materials in the building body, and measures to reduce these.

Emissions related to HVAC systems such as ventilation, firefighting, heating, cooling and sanitation are typically not included in greenhouse gas calculations. This is due to both the lack of environmental product declarations (EPDs) for HVAC components, and a lack of knowledge of how important these emissions are for the buildings' overall climate footprint. Nevertheless, knowledge of material quantities and types in the technical facilities indicates that a complete greenhouse gas account for buildings should include these installations. This is supported by the limited research available, nationally and internationally. In published studies and case projects, HVAC installations usually account for at least 20% of buildings' fixed emissions, depending on the scope of the calculation and the life cycle phases included.

The path to a solution

The research project Green HVAC (2021-2024) aims to increase knowledge of greenhouse gas emissions for HVAC and show the way to a 50% reduction. The project, which has a budget of NOK 9.3 million and is supported by the Research Council, was initiated by Multiconsult together with a number of industry partners.

By linking HVAC components in Revit with emission factors, the project enables HVAC consultants to see which parts of the facilities account for the largest emissions, and thus take design measures to reduce the climate footprint. Our tool has been used in several construction projects and the results confirm that HVAC accounts for 20% or more of the total emissions.

HVAC can account for 40% of emissions in highly ambitious buildings

In a typical reference building, HVAC accounts for around 20% of greenhouse gas emissions, but for highly ambitious buildings where the project has reduced emissions from the remaining materials, the share of fixed greenhouse gas emissions from HVAC will be significantly higher. An example of this is the ZEN project Ydalir School, where HVAC accounts for 24% of the emissions for a typical building (reference), but increases to 39% of the total greenhouse gas emissions (including life cycle phases A1-A3 and B4 and building parts 22-28,31-33,36. Building part 21 is the same in the reference and designed building and is not included) in the highly ambitious building that is designed and built.

HVAC components at the top of emissions

The research project has used the Green HVAC methodology in a number of projects and sees the contours of what typically accounts for the largest emissions. This varies from building to building, depending on the building type, system and material selection. But common to all the results is that building part 36 Air treatment accounts for the largest emissions in the HVAC system, and is in the top 3 for all building parts. One of the most striking findings for Ydalir School is that building part 33 Fire extinguishing accounts for such a large proportion. This has contributed to the R&D project establishing a separate project that looks more closely at the optimization of fire extinguishing systems.

For individual components in HVAC systems, the research community sees three common components at the peak of emissions. These have accounted for the largest contributions in all projects in Green HVAC to date:

• Ventilation ducts
• Ventilation units
• Sprinkler pipes

In addition, heavy radiators, supply air valves, metal cooling pipes and combi baffles can also be highlighted as examples of emission drivers in investigated projects.

The potential for reduction is large

HVAC systems consist of large amounts of metal and especially steel. Since reused products are rarely used or consist of recycled metal, this accounts for large greenhouse gas emissions. Frequent replacement over the life of a building is also an important driver. Strategies to reduce steel quantities, use alternative and less emission-intensive materials, increase and better utilize service lives, and reuse could significantly reduce the fixed emissions associated with HVAC.

How we design facilities, choose air conditioning solutions, and simple choices such as the location of technical rooms and ductwork can have a major effect on greenhouse gas emissions. Our research suggests that the same performance can be achieved with 50% lower greenhouse gas emissions from materials. It is also important that the overall picture of such choices is illuminated. Effects on indoor climate and energy use in operation must be included in assessments to avoid ‘sub-optimizations’ where emissions are moved from one place to another, without reducing the overall climate footprint.

In order to meet the world’s climate ambitions, we in the HVAC industry must also contribute

Through R&D Green HVAC, we as advisors, together with our partners; builders, suppliers, contractors and academia, have gained the focus that the construction industry needs and we will continue to work in 2024 to find good solutions that can create a good indoor climate and reduce emissions in the buildings of the future.

The Green Plumbing research project will conclude in 2024 and a number of articles will be published during the year to spread knowledge about our research. Towards the end of the year, we will also publish a Green Plumbing industry guide.

Further information about Green HVAC

Green Plumbing is an Innovation Project in the business sector, supported by the Research Council of Norway. The project was carried out in the period September 2021 to March 2025.

Project objectives: Building competence, developing new services and sharing knowledge. Showing the way to a 50% reduction in greenhouse gas emissions from HVAC installations in model projects

The project manager is Multiconsult. Partners in the project are Höegh Eiendom, GK, Armaturjonsson, Swegon, KLP Eiendom and Pipelife. R&D supplier is OsloMet. The reference group consists of VKE and FutureBuilt.