Air Conditioning and Greenhouse Gas Emissions.

Introduction and Context

The European Directive of April 2024 on the energy performance of buildings (recast) highlights the need to calculate the Global Warming Potential (GWP) across the entire lifecycle of buildings. This indicator aggregates greenhouse gas (GHG) emissions embedded in construction products, as well as direct and indirect emissions from the operational phase, promoting a more comprehensive and conscious approach to the climatic impact of buildings.

In line with the above, the regulations associated with HVAC (Heating, Ventilation and Air Conditioning) projects are currently highly demanding and rigorous, establishing ambitious commitments for buildings and, naturally, for developers and designers.

Among these, I would highlight today those established in the National Energy and Climate Plan (NECP 2030) for non-residential buildings in the commerce and services sector, which sets out clear objectives to reduce GHG emissions across various sectors, contributing to the achievement of the European Union’s climate targets.

Decarbonisation Targets

Below are the NECP targets – National Energy and Climate Plan – aligned with national and European objectives.

National Targets for Non-Residential Buildings (NECP 2030)
	2030	2040	2050
Primary energy savings (%)	7 %	15 %	28 %
Local renewable energy (%)	11 %	25 %	54 %
CO₂e emissions reduction (%) (vs 2018)	15 %	37 %	68 %
European Economy-wide Targets (EPBD Directive 2024/1275 of 24 April)
	2030	2040	2050
Emissions reduction (%) (vs 1990)	55 %	–	100 %

These targets also include the use of refrigerant gases with a GWP lower than 750 kgCO_₂e.

Scope of Intervention

The table below summarises the scopes considered for emissions calculation.

Table 1 – Emissions classification grid according to the GHG Protocol – Corporate Accounting and Reporting Standard

Type of Emissions	Scope	Definition	Sources considered
Direct Emissions	Scope 1	Direct GHG emissions from sources controlled or owned by the developer	Associated with fossil fuel use (combustion emissions) and refrigerant leakage (fugitive emissions)
Indirect Emissions	Scope 2	Indirect GHG emissions not controlled by the developer	Resulting from electricity consumption
	Scope 3	All other indirect emissions (not included in Scope 2) occurring in the value chain upstream	Associated with equipment procurement (embodied energy), including extraction, manufacturing and transport of equipment and materials

Note 1: Environmental benefits from reuse, recycling or energy recovery programmes must also be accounted for.

Note 2: The selection of refrigerant gases is naturally constrained by manufacturers’ offerings, which are not yet fully aligned with upcoming European Union requirements, significantly limiting equipment selection options.

Note 3: Annex IV of the current European Regulation (2024/573 of 7 February 2024) defines limits and timelines for the use of these gases (see extracted tables below).

Note 4: The estimation of fugitive emissions (Scope 1), resulting from refrigerant leakage over the lifecycle, should be based on IPCC (Intergovernmental Panel on Climate Change) guidelines.

Note 5: The use of hydrofluoroolefin (HFO) gases should also be considered with caution, as their decomposition in the atmosphere may contribute to acid rain.

Note 6: The use of propane or ammonia gases may be preferably considered in outdoor plants or appropriately ventilated areas.

Note 7: The commercial availability of fourth-generation refrigerants (ultra-low GWP) may become a near-term option and should be kept under review.

Strategies

As stated in the Directive, “The obligation to calculate the global warming potential (GWP) of the lifecycle of new buildings represents a first step towards greater attention to building performance across the entire lifecycle and to a circular economy.”

We therefore propose:

For New Buildings

Considering the most appropriate solutions for each case, such as:

• Equipment with higher efficiency (EER, SEER, COP and SCOP), water-cooled where possible;

• Free-cooling solutions;

• Use of refrigerants with lower GWP;

• Variable flow systems for air and thermal fluid distribution;

• Use of renewable energy sources, where possible;

• Selection of equipment with better PEP (Product Environmental Profile) or EPD (Environmental Product Declaration);

• Considering Class A for SACE

Carry out a lifecycle consumption projection for the proposed HVAC systems and, based on this, estimate GHG emissions over the same period, contributing as effectively as possible to the global target defined by the NECP.

For Existing Buildings

Whenever technically and economically feasible, it is recommended to consider the above solutions for new equipment and proceed with two projections for the following years based on reference-year consumption data:
One scenario maintaining equipment with similar characteristics to the existing ones;
Another scenario identifying Improvement Measures;
For each scenario, estimate the reduction in energy consumption and CO²e emissions, define implementation procedures and phasing, and project the future considering a lifecycle of 20 years (?), assessing compliance with NECP targets and establishing a new baseline for future lifecycle updates of HVAC systems.

Economic assessments of investments should then be carried out for each measure and for the overall set of Improvement Measures (IM), taking into account the associated benefits (avoided costs).

Conclusions

We face an unavoidable challenge and our response will undoubtedly play an important role, at least in reducing climate unpredictability.

Luís Malheiro