Climate change: evidence review of mitigation options in the Built Environment sector

5 Shift: a more sustainable built environment

Mitigation options which involve a shift to a lower-carbon built environment include the use of more sustainable building materials and the provision of green and blue infrastructure.

5.1 Sustainable building materials

Qualitative evidence

The built environment co-benefits literature addresses potential impacts arising from a shift towards sustainable buildings and associated building standards (Allen et al., 2015; Chauvin et al, 2016) including utilised building materials ( e.g. Sutton et al., 2011).

The adoption of sustainable building materials ( e.g. Sutton et al., 2011) can reduce the embodied energy of buildings by increasing the production of timber for structural and insulation products. These products can include cross-laminated structural components from both hardwood and softwood timber as well as recycled cellulose, sheep wool insulation materials and Naturally Structurally Insulated Panels ( NSIPs) in new buildings (see e.g. Ecocel, 2016; MAKAR, 2016; NEES, 2013; Sutton et al., 2011; Thermafleece, 2016). Related to the adoption of sustainable building materials in the Scottish context, there are co-benefits relating to the use of forestry, woodland, and agricultural products for reducing operational and embodied emissions from buildings, through increasing the supply of timber products for manufacturing structural components and insulation materials. There was a clear consensus in the Scottish Forestry Strategy (Forestry Commission Scotland, 2006) that more could be done to achieve its aims, and that this could also leverage a wide range of co-benefits, including:

• increasing forest and woodland coverage (and sequestering carbon);
• socio-economic benefits for rural communities through increasing the production and diversification of forestry and agricultural co-products;
• supporting tourism and public health through better managing forestry and woodlands for biodiversity and recreation.

Research also suggests that natural and sustainable building and furnishing materials can improve indoor air quality by absorbing VOCs and regulating moisture and heat (James and Yang, 2005; Lee et al., 2005; NEES, 2013; Osanyintola and Simonson, 2006; Simonson et al., 2002).

Quantitative evidence

There is currently limited quantitative evidence and modelling related to the above benefits, and there is a particular need for increased and improved data on Scottish imports and exports of sustainable building materials in order to better understand and quantify the potential for these industries to contribute to sustainable economic growth.

5.2 Green and blue infrastructure

Qualitative evidence

Green infrastructure includes natural and semi-natural features such as parks, gardens, woodlands and urban trees, as well as man-made features such as green walls and roofs. Blue infrastructure includes lakes, rivers, wetlands and smaller water features such as ponds and ditches for sustainable urban drainage (Sandström, 2002). These networks of structures and facilities are essential for maintaining connectivity in landscapes and deliver a multitude of social, economic and environmental benefits (Forest Research, 2010; Tzoulas et al., 2007). Increasing green and blue infrastructure in urban areas has significant potential to deliver co-benefits as part of climate change mitigation, climate change adaptation and sustainable development strategies for cities ( e.g. Hollas, 2014; Huseynov, 2011).

The provision of green infrastructure has been cited as a prerequisite for forming healthy communities (Mazza and Rydin, 1997), and there is a large and growing volume of evidence of the benefits of access to green spaces on the health and wellbeing of people of all ages ( e.g. Curl et al., 2016 and Teedon et al., 2014). Green infrastructure in urban areas can also help reduce the urban heat island ( UHI) effect, thus reducing building energy demand for cooling and reducing the health risks to occupants, and particularly to elderly and vulnerable householders (Emmanuel and Krüger, 2012; Emmanuel and Loconsole, 2015; Glasgow Clyde Valley Green Partnership, 2013; Hollas, 2014; M'Ikiugu et al., 2012).

Green roofs, often referred to as living roofs, and green walls are vegetative layers on the roofs or walls of buildings with waterproofing, drainage and irrigation characteristics (Castleton et al., 2010). They have become increasingly recognised for the benefits they offer (Bianchini and Hewage, 2012; Kowalczyk, 2011), which compensate for the expenditure required in installing them, including:

1. Energy demand reductions from insulating the property

2. Reduction of Urban Heat Island ( UHI) effects

3. Management of surface-water run-off

4. Improved external air quality

5. Absorption of GHG emissions

6. Habitat creation and biodiversity enhancement (Bianchini and Hewage, 2012; Castleton et al., 2010; Rosenzweig et al., 2006).

Quantitative evidence

Quantitative models and associated analysis as they relate to air quality aspects are covered in Chapter 7. There is currently limited consideration of green and blue infrastructure within a co-benefits modelling framework and it is recognised that there are challenges in evaluating the benefits of certain aspects e.g. the difficultly in attributing wellbeing related changes (in relation to physical activity or mental health) to a specific green infrastructure improvement (Smith et al., 2016). There is, however, a broader range of evidence e.g. in terms of impacts of energy demand reductions (as discussed in Chapter 4) which could be drawn upon in potential future model development.