Cutting Embodied Carbon
This year, England, Scotland and Wales are taking significant steps towards achieving net zero carbon emissions with the introduction of tougher building energy efficiency standards. In addition to these efforts to cut the operational impact from buildings, there is also growing pressure to address their embodied impact. These are the emissions from the processes needed to construct, maintain and deal with a building at end of life. As a result, project teams are being increasingly asked to consider these factors as part of the design and specification of projects.
A notable part of the emissions from the initial construction phase comes from road transport used to deliver construction materials to site. New research from Rider Levett Bucknall (RBL) has now shown that by using thinner, more thermally efficient pipe and duct insulation solutions, it is possible to insulate greater lengths of building services from each lorry load. The study shows this can help to significantly reduce the number of deliveries needed to site and, as a result, shrink associated carbon emissions from product deliveries by as much as 66.67% for pipe insulation and 33.41% for duct insulation solutions.
Impact of efficient insulation
A key performance metric for any building insulation product is its thermal conductivity (also known as lambda value). Materials with lower thermal conductivities are more effective at preventing heat transfer at a given thickness. In the building services sector, this can be useful both to improve heat retention in applications such as LTHW or DHW pipework, or keeping air or water cool as they circulate through air conditioning ductwork or chilled pipework.
In practice, the thermal conductivity of the insulation material can have a significant impact on what thickness is needed to achieve the minimum level of heat transfer. For example, the table below compares a mineral fibre pipe insulation product with a thermal conductivity of 0.033 W/mK at +10°C with a phenolic insulation alternative which has a thermal conductivity of 0.025 W/mK at +10°C. The comparison looks at a typical application on a non-domestic low temperature heating water system (<95°C) and identifies the minimum insulation thickness needed to meet the requirements in BS 5422:2009 across a range of pipe diameters.
SEE FIG 1 (Below)
As you can see, in some cases, the lower performing mineral fibre pipe insulation needs to be twice as thick as the phenolic alternative to achieve the same rate of heat loss.
Similarly, a comparison of heated ductwork lagged with mineral fibre (thermal conductivity 0.034 W/mK ) with a pre-insulated phenolic ductwork system (thermal conductivity of 0.025 W/mK at 25°C) showed that to achieve a heat loss rate of 16.34 W/m2, a 22 mm thickness of the pre-insulated phenolic ductwork system was needed compared with a 40 mm thickness for the mineral fibre lagged ductwork.
In addition to the obvious implications this has for the amount of space needed for building services and ease of installation within service spaces, this can also impact the total length of pipe or ductwork which can be insulated with each lorry load of materials. Kingspan Technical Insulation commissioned RBL to carry out a study looking at how this could impact the number of site deliveries and associated carbon emissions.
Total coverage per load
To understand this, RBL first looked at the total length of pipework or area of ductwork which could be insulated to BS 5422:2009 with a single delivery from a typical, 44 tonnes haulage vehicle.
The analysis of pipework products considered the pipe insulation, pipe insulation support inserts and all associated packaging. Two different solutions were assessed across a range of pipework systems and pipe diameters:
• mineral fibre pipe insulation (0.033 W/mK at +10°C)
• phenolic pipe insulation (0.025 W/mK at +10°C)
The outputs showed that between 8.33% and 146.53% more linear metres of pipework could be insulated with the phenolic pipe insulation specification depending on the pipework system type and pipe diameters.
RBL then looked at two different ductwork solutions including coupling systems for warm air and dual ductwork:
• sheet metal ductwork lagged with mineral fibre insulation (0.034 W/mK);
• pre-insulated phenolic ductwork (0.025 W/mK at 25°C)
This showed that between 33% - 40% additional square metres of the pre-insulated phenolic ductwork could be carried in a 44-tonne lorry.
Based off this analysis, RBL were then able to calculate the expected greenhouse gas (GHG) emissions associated with deliveries of the insulation solutions for a range of applications.
These calculations initially looked at the number of deliveries and associated GHG emissions when delivering pipe insulation and insulated pipe support inserts for 10,000 metres, 20,000 metre and 40,000 metre lengths of pipework. The results showed that total GHG emissions could be as much as 66.67% lower with the phenolic pipe insulation specification compared with the mineral fibre specification.
For the ductwork insulation solution comparison, RBL considered the number of deliveries needed to provide 1,000 m2, 2,000 m2 and 4000 m2 areas of ductwork. Again, the results showed that the total GHG emissions with the pre-insulated phenolic ductwork could be up to 33.41% lower than the mineral fibre lagged sheet metal alternative.
To get a clearer idea of how the choice of pipe and ductwork insulation could impact carbon emissions from an actual project, RBL then carried out modelling based on the full building service specifications from several real-life case studies. This modelling assumed all materials were being sent from the same manufacturing site in Herefordshire and includes emissions from complete round journeys.
They first looked at a hotel in Warwickshire which required over 15,000 linear metres of pipe insulation. It was assumed that half of this was for a low temperature heating system (water ≤ 95°C) and the other half of the pipe insulation for the domestic hot water (60°C) services. Both systems include a range of pipework diameters.
The results showed that with the phenolic pipe insulation specification, the pipework could be insulated with two deliveries from a 44-tonne lorry. In contrast, the mineral fibre specification required a further two site deliveries. This meant that by using the phenolic specification, GHG associated with product deliveries could be halved from 1,497.25 KgCO2e to 748.63 KgCO2e.
RBL then looked at a separate case study of a leisure centre in Gloucester which required approx. 9000 m2 of 30 mm thick pre-insulated phenolic ductwork to fabricate dual purpose ductwork in a variety of sizes from 200x100 mm to 1800x1200 mm. It was estimated that 18 journeys would be needed to deliver all of these system components compared with 27 deliveries for a comparative system using galvanised steel ductwork with 50 mm thick mineral fibre lagging. The results showed that total GHG emissions from delivering the pre-insulated phenolic ductwork solution were 2,917.78 KgCO2e - a 33.33% reduction on the mineral fibre specification.
The race to decarbonise our built environment has placed considerable pressure on mechanical and engineering specifiers to deliver operational savings. It is, however, important to stay aware of the role of embodied carbon and new requirements and targets which are expected to be introduced. For example, the Welsh Government has already introduced requirements for all new school projects to demonstrate a 20% reduction in embodied carbon. The RBL study clearly demonstrates that the use of thinner, more thermally efficient pipe and ductwork insulation solutions can help to deliver considerable savings on transport related carbon – helping to cut down on this key source of embodied carbon.
Marc Nickels is Business Development Manager at Kingspan Technical Insulation