Carbon reduction guidelines by components

Carbon reduction guidelines by components

Recommendations are given for the following building components: substructure, superstructure, structure, envelope, finishes and furniture, site, design for manufacturing and assembly.

Substructure

Use fewer materials - Material efficient design should be applied and reduce the amount of materials used and the overall building weight. An optimization of the buildings layout can be performed. Reuse of existing substructures is stimulated, when possible. The whole life carbon impacts of any thermal mass benefits should be taken into account.

Use low carbon materials - Using recycled reinforcing steel. Opt for reusable formwork to reduce waste. For retaining walls pre-cast units can be considered, which may allow higher cement replacement, or using geotextile reinforced earth walls.

Use concrete alternatives such as Limecrete or Hempcrete where performance requirements allow, such as in ground floor slabs. Investigate low-carbon options such as timber piles (used in maritime applications), rubble trenches or dry-stack masonry. Use low-carbon below-ground insulation such as foamed glass.

Reduce waste - Use recycled aggregate where possible for ground work. On site waste can be effectively reduced by applying material efficient design, prefabrication and modular construction.

Adaptability – It is advisable to design the building for future adaptation and changes in use. Also, the building should be designed for climate resiliency, as in the future there may be larger swings between wet and dry, or hot and cold weather.

Structure

Use fewer materials - Preserve and re-use existing structures wherever possible. Review and reduce loading requirements Reduce spans taking into account the impact on long-term flexibility. Design lighter facades that allow larger deflections at slab edges. Post-tensioning can be used in order to reduce the concrete volumes. Forms that minimize material use, can be applied, especially in larger spans, such as coffered slabs. Using re-usable formwork to reduce the amount of waste. Using concrete as a surface finish to minimize use of other internal finishes.

The buildings` structural elements can have a dual purpose, that is, they can serve as a shading device instead of constructing additional shading elements to control solar gain.

Use low carbon materials - Consider the carbon impact of the cladding elements. Sustainably sourced cross laminated timber (CLT) usually has lower embodied carbon than steel or concrete. Consider low embodied carbon materials such as timber, rammed earth, straw bale panels etc. when possible.

When using steel, priorities high recycled content and shorter transport distances to site. Priorities highest possible cement substitution with industrial by-products and use recycled aggregates if they are available, such as : Pulverized Fuel Ash (PFA), aka ‘Fly ash’ and Ground Granulated Blast-furnace Slag (GGBS).

Reduce waste - Use prefabrication, modular design and Design for Manufacture and Assembly (DfMA).

Adaptability - Modular design – consider separating structural elements from functions that could be changed or moved as part of future adaptation. Consider spans, loads and structural grids that allow for changes and alternative uses, particularly if designing for typologies that may become obsolete in the near future (example: car parking).

Disassembly - Avoid composite materials (e.g. concrete on metal deck), which may be hard to deconstruct in future. DfMA strategies are most likely to allow for deconstruction and reuse. The connections between the structural components should mechanical instead of chemical in order to be easily disassembled, need to be visible and reversible

Buildings` envelope (facade and roof)

Buildings` facade can be carbon intensive depending on the materials used, supporting systems, fixings etc. In facades where steel or aluminum substructure is used it can significantly increase the embodied carbon (recycled steel is recommended). Also, the life expectancy of the facade system should be considered alongside the embodied carbon value.

Use fewer materials – Apply material efficient design, prefabricated and modular design in order to reduce total material use and weight. Using BIM platforms in the buildings 'design can facilitate this process.

Use low carbon materials - Perform detailed analysis of the materials applied in the buildings envelope and look for low-carbon materials as substitution.

All parts of the building component should be considered, such as for example the metal secondary framing in structural façade which often contains the most embodied carbon. Overall the use of metal components should be reduced, or recycled components to be used. Some recommendations are:

 Lime render or mineral wool can have a big impact in achieving lower embodied carbon.  Traditional brick build-up can be a low carbon solution and further enhanced by using recycled bricks and lime mortar. Use of lime mortar enables bricks to be reused at the end-of-life.  Timber framing can often be used instead of metal framing (fire regulations should be considered).  All timber should be from regulated and responsible sources.

 Specify aluminum from a source that uses less carbon-intensive production methods – Polyester Powder Coating (PPC) aluminum is easier to recycle at the end-of-life than anodized aluminum, but needs more maintenance.  Reuse when possible materials, building elements and/or whole buildings previously utilized that are repurposed to construct a new or retrofitted building, in place of using virgin materials/new building elements.

Reduce waste - Where appropriate, design for repetition and off-site manufacture. Use standard sized components and materials.

Adaptability – Façade design using Passive and Active design technologies. Façade that can adapt and regulate the heat transfer through it, thus contributing to lower energy consumption for heating, cooling and lighting. Use of shading devices, operable windows etc. Use of adaptive facades, kinetic facades, smart materials and other technologies.

Disassembly - Consider prefabricated components with mechanical joints for easier disassembly.

Finishes, Furniture Fixtures and equipment (FF&E)

How to use fewer materials -

 Utilize self-finishing internal surfaces like cement, concrete, timber etc.  Use materials with recycled content  Avoid harmful chemicals like formaldehydes and VOCs.  Take into consideration the need for maintenance, repair and replacement.  Choose products that do not rely on adhesives so fabrics or finishes can be replaced.

Use low carbon materials -

 Use materials with a high percentage of recycled content, (e.g. carpets).  Compare materials EPD and apply materials with lower environmental emissions

Reduce waste -

 Durable materials will last longer, and require fewer replacement cycles over a building’s lifespan. Sometimes this enduring quality may come at a higher upfront embodied carbon cost but this may be a price worth paying to avoid later replacements.  Take into consideration the expected lifespan of the building and likelihood for changes to interior finishes when specifying materials that are long-lasting and high embodied carbon.

Disassembly -

 Internal finishes are often in their nature difficult to disassemble for