The Finnish government has set the goal that Finland will be carbon neutral in 2035 and carbon negative quickly thereafter. It has been said that all stones must be turned because the goal is ambitious. This also applies to construction. At the same time, it is important to pay attention to the fact that the intended actions are effective and realistic.
Evaluating the carbon footprint of buildings is important in order to obtain sufficiently accurate information to support various decisions. What is done with the information determines the level of accuracy, transparency and traceability requirements.
Climate survey as a condition of the building permit
In connection with the comprehensive reform of the Land Use and Construction Act, the Ministry of the Environment is planning to include the low-carbon assessment and related carbon footprint limit values for new buildings in the regulations. Information about the building's low carbon footprint should be given in the form of a carbon footprint in the climate assessment, which would be a condition for obtaining a building permit.
For example, the standard carbon footprint limit value for a residential apartment building would then have to be lowered.
The Ministry of the Environment's legislative proposal does not yet say how the climate report prepared by the person undertaking the construction project would function as part of the construction permit process. Open questions are, with what precision the climate report should be prepared, and what would be the permitted level of uncertainty for the results, and how the uncertainty would be presented.
Information is needed on the qualification requirements of the author of the climate report and on the other hand of the verifier, as well as how the authority would check or verify the calculation. It would also be important to know how the implementation of the climate assessment prepared in accordance with the plans would be verified in connection with construction and whose actions would be taken. Still unanswered are the follow-up measures in situations where the climate assessment does not correspond to what was announced at the construction permit stage and the limit value requirement is exceeded.
If the level of uncertainty was allowed?
There has been very little open discussion between the various parties about the permitted level of uncertainty in the climate assessment. To promote that, we have, among other things, calculated the sources and level of uncertainty in the carbon footprint calculations of buildings. In the carbon footprint calculation based on life cycle assessment, there are a lot of assumptions, assessment containing scenarios and calculations that produce imprecise results.
A clear definition of the required accuracy would be needed so that the calculation could be applied as a legal procedure attached to the building permit. For example, would an uncertainty level of one, five or thirty percent be allowed in the calculated value of the carbon footprint?
At the same time, the required level of accuracy also determines what the carbon footprint calculation method should be and how accurate the starting data is needed for the calculation. This required accuracy of the initial data in turn has a very practical connection to at which stage in the building design process sufficiently accurate data is available.
The carbon footprint calculated before the construction permit stage would be based on assumptions
Construction projects have different forms of implementation. In most of them, the materials that will be used definitively and their detailed quantities will only be known after the construction permit phase. The carbon footprint calculation performed in the general planning phase of the building before the building permit would therefore be largely based on assumptions, because sufficiently accurate quantity and emission data of building materials are not yet available. Therefore, in connection with the current way of implementing construction projects, the carbon footprint calculation results presented at the construction permit stage can inevitably be very inaccurate.
The most relevant question about the uncertainty of the climate assessment and its level is to include the assessment of the energy emissions of the building during its use in the life cycle assessment. It is very significantly affected by the specific emission factors of different forms of energy – especially electricity and district heating. In the draft evaluation method that is currently in the opinion, the assumption and scenario model is a drastic drop in energy emissions already in the near future. If the development does not materialize according to the assumptions, the size of the building's carbon footprint can drop considerably.
Can a building type have one limit value?
As stated above, the developer of the construction project would be obliged to verify the result of the climate assessment carried out in the planning phase before the building is commissioned. However, the result of the assessment is the cumulative amount of emissions formed over the entire life cycle of the building. A good question is how and by whom the carbon footprint created during the building's use is verified. It will continue to be the most significant part of lifetime climate impacts for a long time to come.
A more detailed follow-up discussion would also be required as to how it would be possible to determine single limit values for different building types according to the draft regulation. In practice, a single limit value model would mean comparing buildings with very different technical and functional characteristics to each other.
It is difficult to justify the same limit value requirement for, for example, a four-story and a forty-story residential apartment building because of their different structures. The carbon footprints of even two identical apartment buildings can vary greatly due to, for example, the type of heating, the foundation conditions of the plot or the implementation of the required parking spaces.
If and when the goal of regulatory development is to have a guiding effect on the low carbon of buildings and the reduction of the carbon footprint, it must happen credibly and without jeopardizing various life cycle properties and life cycle quality factors. The carbon footprint is increased by many factors that improve the properties of the building, such as sound insulation or long-term durability.
A half-serious saying states that "the minimum of regulations is the maximum of construction". In the worst case, this can become very true if there are limit value requirements based on wrong principles.
There is still more need for a joint open discussion about low-carbon methods. The positive side of the matter is that in low carbon, many things, such as uncertainties, can be clarified and calculated.
Pekka Vuorinen, director of environment and energy, Construction Industry RT
Jani Kemppainen, expert, Construction Industry RT
Henrik Österlund, Executive Vice President, Ecobio Oy
The text has been published Rakennuslehten On the Näkökulma column on 17.6 November XNUMX.
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