2.2.3. Other Materials

At present, polystyrene and mineral wool are the most frequently used for insulating buildings [127], with mineral wools in general having a lower carbon footprint, which is why material substitution together with recycling is a current abatement measure for insulation [74,104]. Other abatement measures include fuel change together with energy e fficiency measures for production of both mineral wool and polystyrene insulation [37,128,129]. Steam cracking is responsible for a large share of the carbon footprint (~40%) of plastics production [37] (which is also a raw material in polystyrene insulation), which is why deep abatement options for plastics production include electrification or carbon capture in cracking and polymerization [37,90]. Other abatement measures for plastics include material e fficiency measures and recycling either by mechanical or chemical means [38,41,47].

In the production of gypsum for plasterboards, the most prominent abatement measure is the use of recycled gypsum which can be combined with electrification or biofuel substitution in the heating furnaces used in the gypsum production [130].

Main abatement options for asphalt include biofuel substitution, lowered temperatures, and increased recycling rates [80,131,132].

## 2.2.4. Material E fficiency

Material e fficiency is a key abatement measure for all construction materials, and a measure that generally deserves more attention in policy and climate mitigation discussions. Evidence (see, e.g., Reference [37,38,44,47,133]) suggests that, on average, one-third of all material use could be saved if designs were optimized for material use rather than for cost reduction, since downstream production (and design) are generally dominated by labor costs and not material costs. For example, it is easier to use constant cross-sections across a structure than to design each beam and column individually since this leads to more rapid construction.

In addition, motivations to use excess material are driven by an asymmetry costs of product failure compared with the costs of over-specification, by over-specified components copied across projects to minimize costly design time, by cheaper manufacture of standard parts, and by the fact that many products experience higher loads prior to use (in installation or transport) than in use [46].

#### 2.2.5. Construction Equipment and Heavy Transports

High potential abatement measures for heavy vehicles and machinery in the short to medium term include biofuel substitution, energy e fficiency measures, hybridization, and optimization of logistics and fleet management. Over the longer term, deeper emissions reductions would result from electrification of construction equipment, crushing plants and heavy trucks. For the latter, options include plug-in hybrid or fuel-celled heavy-duty trucks/haulers potentially in combination with electric road systems. Model shifts for heavy transport to rail and ship is also an abatement measure with large potential. While such shifts are out of scope for this analysis, this is an important level towards a more transport-e fficient society [134].

#### 2.2.6. Summary of Abatement Options

A summary of all abatement options and their identified emission reduction potential are described in Figure 5. The graph illustrates the range of GHG emissions reduction potential recognized in literature for each of the abatement options explored, where the range may depend on the level of the abatement measure that is adopted. Full details of measures for all activities, including timelines, potentials, and references, are available in the Supplementary Material.

**Figure 5.** Range of greenhouse gas (GHG) emissions reduction potential for the abatement options identified in the literature review for the main emissions sources (color coded). The study analysis is based around reaching the medium-high range of the emission reduction potentials for each selected abatement measure when fully implemented. The Supplementary Material provides full details of measures for all activities, including timelines, potentials, and references.
