The modelling involves both energy and non-energy renovations. The energy efficiency improvement of the building stock enabled by energy renovation is not calculated but is accounted for in terms of the ‘depth’ and speed of the renovation. Although deep energy renovation implies increased use of insulation materials and therefore increases in embedded CO_2, it can also lead to reduced CO₂ emissions post renovation. By further increasing the recycling rate of insulation and other materials, further savings in material extraction and CO₂ can be achieved (see page 20 of the background report for more details).

Circular renovation actions

Three main circularity objectives can be addressed through circular renovation actions:

Under these objectives, we modelled 10 circular renovation actions. These are presented in Table 1 and are clustered by objective.

Table 1. Circular renovation actions

Modelling renovation impacts on the EU building stock

The potential impacts of applying these 10 actions to the EU building stock were estimated in a modelling exercise that applies three scenarios. Based on the literature, a baseline scenario assumes a continuation, until 2050, of current renovation rates and activities, broken down into energy- and non-energy-related renovation. A second ‘policy-compliant’ scenario accelerates the renovation rate according to the aspiration of the EU’s renovation wave. A third, more ambitious, scenario further accelerates renovation, so that all buildings in the stock will have been renovated by 2050.

The results are shown in Figure 2, in which the annual cumulative savings of materials and GHG emissions are shown for each of the 10 modelled circular renovation actions.

Figure 2. Cumulative savings of materials and GHG emissions for each circular renovation action from 2022 to 2050

Note: Carbon storage is not taken into account.

Table 2 shows the cumulative savings of materials and GHG emissions over the entire modelled period of 2022-2050 for each circular renovation action and also for each cluster/circularity objective (see Table 1). The results for each cluster cannot be obtained by simply summing the results of individual actions, as the actions can overlap. A negative value indicates a higher cost (of materials or emissions) than the foreseen benefit.

Table 2. Material and GHG emissions savings from implementing circular renovation actions on the EU building stock

Notes: Adding together the results of each circular renovation action is not possible because of overlaps in the activities included in each action. The sum of results by cluster takes these overlaps into account.
(*) The range represents results according to each scenario modelled: lower limit for baseline, upper limit for ambitious.
CO₂e, carbon dioxide equivalent.

From Table 2, it becomes evident that focusing on renovation actions that aim to directly increase buildings’ lifespans has the greatest potential for both material and GHG savings in the period modelled. This is because increasing lifespans is translated into lower demand for new construction, which is very material and GHG intensive. Increasing the intensity of use also brings substantial CO₂ savings. This action can be attributed to considering energy sufficiency, which is a crucial topic in reducing emissions from buildings (IPCC, 2022).

Meanwhile, investing in long-lasting materials presents a different picture: the results for this action demonstrate a net consumption of materials and a cost in terms of GHG emissions in the baseline scenario. This is because most of the long-lasting materials are heavier and more GHG-intensive during production than traditional materials. However, their long-lasting nature means that renovation will be needed less frequently in the future, thus avoiding the use of renovation materials and the associated embedded GHG emissions. This action demonstrates that, in some cases, circularity demands investment in materials now to harness benefits in the very long term, because of buildings’ inherently long lifespans. For example, if the period modelled is extended to 2070, the scenario results for GHG emissions become net savings of between 19 and 38 million tonnes CO₂e. These results also illustrate the different strategic choices possible: if achieving rapid emissions reductions in the short term leads to the underuse of long-lasting materials, this will be at the cost of lower long-term reductions in emissions.

The second cluster in terms of material and GHG savings consists of actions that focus on reduced material consumption, mainly by boosting high-quality recycling of materials. Benefits come from the fact that almost no new resources are needed when recycled material is used, which is also much less GHG intensive to produce than materials using extracted new natural resources. Especially in the ambitious scenario, in which renovation is significantly accelerated, using materials with a high recycled content in renovation is the circular action with the highest potential for achieving savings in GHG emissions.

The more experimental circular renovation actions in the last cluster demonstrate the lowest, but not insignificant, potential for savings in GHG emissions. However, in terms of material savings, using bio-based materials and green solutions requires a greater material mass than the current conventional alternatives. This is because bio-based materials are either heavier or have shorter lifespans (which means they need to be replaced sooner in a subsequent renovation) than their alternatives. However, because these bio-based and green materials are renewable, the issue of resource depletion becomes less important if they are used — assuming that sustainable production is ensured. Interestingly, installing green facades and roofs during building renovation would mean that the balance of GHG emissions becomes negative, as green elements are heavier than existing alternatives and thus more GHG intensive to produce per unit. However, the GHG emissions cost is low, and they offer a wide range of benefits: for example, installing green facades and roofs in most of the buildings in Europe offers recreational opportunities, climate adaptation to heat stress, cooling the air temperature, carbon sequestration, storm water treatment and management, and increased biodiversity (EEA, 2021b).

Conclusions

Buildings feature strongly in both climate and circular economy policymaking in the EU. Achieving climate neutrality implies not only reducing buildings’ energy demands and decarbonising the energy used but also reducing emissions from a life cycle perspective. Embodied GHG emissions account for on average 20-25% of the total life cycle emissions from buildings and will become increasingly important as the building stock becomes more energy efficient (Röck et al., 2020). In new constructions, many circularity benefits will often be realised far into the future. Increasing the lifespans of buildings and design-for-disassembly are examples of circular measures that will confer benefits once new buildings reach the end of their life, many decades from today. It is important, therefore, to also focus on the way we renovate our existing building stock, so that the benefits are harnessed in the shorter term.

The modelling presented demonstrates that applying a more ‘circular renovation wave’ in Europe could have a synergetic effect in both minimising resource use and avoiding GHG emissions. The 10 actions modelled offer diverse renovation activities and could also offer substantial savings in GHG emissions^[1].

Recognising the climate mitigation potential of embedded greenhouse gas in buildings, the EU is already planning a whole life cycle performance roadmap to reduce greenhouse gas emissions from buildings by 2050. Similar initiatives by construction sector stakeholders (World Green Building Council, 2022) indicate a demand for decarbonisation in the sector that adopts a life cycle perspective.

The EEA will continue to invest in producing policy-relevant knowledge on buildings.