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CO2 in construction

Combating climate change and reducing emissions is an enormous battle where every action matters. Thus, we are very interested on what Mestamaster and takt time could potentially do to reduce emissions.




To understand this challenge, let’s start with the big picture. According to IEA, the buildings and construction sector accounted for 36% of final energy use and 39% of energy and process-related carbon dioxide (CO2) emissions in 2018, 11% of which resulted from manufacturing building materials and products such as steel, cement and glass.


That is quite wide perspective, which we need to narrow down quite a bit to get the emissions from the actual process of construction:

  • 11% manufacturing building materials

  • buildings 27%, of which 8% being direct emissions in buildings and 19% indirect emissions from the production of electricity and heat used in buildings

Adding above figures gives us 38%, which means that overwhelming amount of emissions could be reduced by making energy and construction material production less carbon-intensive. Calculating from these figures, the actual construction process emissions are about 1%.


Now we need to figure out what are the causes for emissions in the construction process. Luckily, our good friends and customers Respect Project have made their own carbon emission report:

Source of emissions

Emissions t CO2e

% of carbon footprint

Subcontractors

897,56

81 %

Building materials and tools

128,83

12 %

Fuels

66,44

6 %

Manufacturing of fuel

13,32

1 %

Rented tools

1,82

0,2 %

Energy

0,00

0 %

Total

1107,97

Their carbon footprint was 140 t CO2e / M€ measured in revenue, which is below EU average 191 t CO2e / M€.


As the main contractor and project leader, most of the emissions fall under Subcontractors. Here we need to dig deeper on whether subcontractors have similar profile on their emissions as Respect Project has. Transforming the estimates of subcontractors emissions from Repects’ respective shares we get following figures:

Source of emissions

% of carbon footprint

Building materials and tools

63%

Fuels

30%

Manufacturing of fuel

0,5%

Rented tools

0,1%

Energy

6,4%

*) Building materials and tools are removed from the calculation as they are already included on the 11% share of building and construction sector.


Here we have estimated that subcontractors' energy is as carbon intensive as the Finnish grid is on average. However, this share of energy usage might not be representative of the actual usage. Let’s take a look at a summary of research reports on construction process emissions. Hämäläinen studied the energy use on two residential construction projects, where main energy usage was heating and drying with ventilation with shares of 69% and 75%. Energy usage was divided per source:

Case 1

Case 2

Volume m3

22500

14161

Electricity kg CO2e

46839

25,7%

43318

29,5%

District heating kg CO2e

89080

48,8%

26534

18,0%

Fossil fuels kg CO2e

46567

25,5%

77197

52,5%

Total

182486

147049

Using averages from table above, energy usage is divided more evenly between fuels and electricity/district heating.

Source of emissions

% of carbon footprint

Building materials and tools*

63%

Fuels

21,8%

Manufacturing of fuel

0,5%

Rented tools

0,1%

Energy

14,2%

And the version that has been cleaned from materials:

Source of emissions

% of carbon footprint

Fuels

59,6%

Manufacturing of fuels

1,4%

Rented tools

0,2%

Energy

38,8%

Now we are getting close to the answer to original question: can Mestamaster help lower carbon emissions? Our construction app and process enables cutting construction time about 20%. It’s clear there is no effect on the usage of building materials and tools, same amounts are required regardless of time it takes to install them. Let’s look more close the other items on the list.


Fuels

When using takt time on construction site, there is clear focus on eliminating waste. Elimination here means getting rid of unnecessary driving around as the logistics and flow of work is well organised. Biggest elimination still comes from reducing the duration of the project. The reduction can be 59,6% * 20% = 11,92%.


Electricity and district heating

Similar potential of savings are with electricity and district heating. District heating can be reduced fully by the amount of duration cut down. 56,2% of energy usage was district heating, reduction 56,2% * 20% * 38,8% = 4,36%


Electricity is used for heating and ventilation but also on tools that require the same workload to complete the task, no matter how long the project takes. Hämäläinen has measured division of electricity consumption:

  • Lighting 55%

  • Drying 19%

  • Construction booths 10%

  • Tower crane <1%

Use of takt helps minimise lighting and construction booths electricity consumption while drying and tower crane are unaffected. Energy savings 43,8% * 65% * 20% * 38,8% = 2,21%


Total savings on fuels, electricity and district heating: 18,49%

Conclusion

Based on publicly available material, Mestamaster and takt time could help reduce construction project’s emissions 18,49%. Of the overall emissions of the buildings and construction sector, we could help reduce 0,072%. That might not sound big, but total global emissions was 37,12 Gt CO2e in 2021.

0,072% reduction of total emissions is 29 460 813 t CO2.

Caveat here is that transforming energy sources to carbon neutral has the biggest effect on emissions. As more and more energy is carbon neutral, CO2-savings from production process improvements will go down. As we are racing towards those solutions, there is already a solution that allows reduction of emissions immediately? What are we waiting?

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