4. Greenhouse Emission Calculations as a Driver for Design
Kimmo Lylykangas
Kimmo Lylykangas is a professor of architecture and head of the Academy of Architecture and Urban Studies at the Tallinn University of Technology. He has held research and teaching positions at Aalto University 2003-2012 and Umeå School of Architecture 2014-2016 as well as running his own practice since 1996.
Science has warned us about climate change already for a century. The first Swedish Nobel laureate, Svante Arrhenius (1859-1927) was the first scientist to estimate the influence of atmospheric CO2 on the temperature of the environment. A hundred years later another Swede, Greta Thunberg, twice nominated for the Nobel Prize, persistently appeals for policymakers to acknowledge the warnings of scientists about the consequences of climate change.
The climate crisis has spurred an increasingly expanding number of architects into action. At the time of writing this paper, 146 Finnish architecture offices have signed the Architects Declare (1) declaration focused on the dual crisis of climate and biodiversity. ACAN (Architects Climate Action Network)(2), founded in 2021 brings together climate activists working with the built environment.
Architects, however, seem to prefer to rely on first-hand knowledge rather than science or quantitative analysis. This is probably because architecture is synonymous with the quality of the built environment and when assessing architectural quality, quantitative methods are useless.
Climate change caused by humans is, however, a quantitative problem. Greenhouse gas emission calculations are a numerical model of the factors that cause global warming. From the architect’s standpoint, the outcome of the calculation should not be the only interesting factor. We should be equally interested in the mechanisms depicted by the model and the parameters that influence the result the most. This lets us know which design solutions we should focus on to maximize our impact on greenhouse gas emissions.
Climate change indicators are increasingly applied also in judging architectural competitions. A simple calculator for the carbon footprint of the building materials and material efficiency was developed by the Finnish Environmental Institute and Pöyry Building Services Ltd already in 2010 and used to judge the architectural competition for an office building in Finland (3). Last year, in a competition for a low-carbon sustainable block in Verkkosaari, Helsinki, half of the possible maximum score for each entry came from quantitative factors: an energy efficiency indicator, a “green coefficient” as well as carbon footprint (4).
The Verkkosaari competition reveals that this type of competition setup isn’t fully functional yet. In the end, the jury selected the best entry. However, assessing qualitative and qualitative design aspects on the same scale is problematic. There is no need to use quantitative evaluation criteria to justify awarding the architecturally superior proposal. Lack of transparency regarding the chosen parameters will only reinforce the profession's wariness of such tools. If the objective is to discover innovative solutions for sustainability, better criteria than computations set by regulatory authorities can be developed, especially since in Finland the interpretation of such calculations is left up to individual municipal local building control officials whose interpretations may vary.
Calculation reports rarely provide sufficient information on how the results were achieved, nor does usually the software used to produce such reports. Still, significant decisions and investments are made based on such reports. These kinds of reports would be significantly more useful and trustworthy if they were required to contain detailed enough information that anyone could replicate the calculation and achieve the same results.
In this paper, I will assess commonly used evaluation criteria for greenhouse gas emissions of the built environment, assessing especially how these criteria influence design.
The carbon footprint of a building
In Sweden, Norway, and France, the carbon footprints of new buildings are regulated by national building codes from the beginning of 2022. Among others, Denmark, Finland, and Estonia are preparing their own carbon footprint regulations. The carbon footprint of individual buildings is assessed based on lifecycle as well as European standards applied nationally.
National regulation can have a significant impact. In principle, it is based on limiting values, which prevent solutions that perform worse from being carried out throughout the building stock. Regulation helps develop competence within the construction industry: a new method sparks the need for new products and services and creates an understanding of best practices, which can be utilized when setting project-specific objectives.
Regulatory control extending to the carbon footprint of construction materials has at least two kinds of effects:
manufacturers of materials develop their processes to achieve a lower CO2 (carbon dioxide equivalent) emission factor
designers choose low-emission materials and products
Should carbon-free steel be produced, or the use of low-carbon concrete become widespread, the Ministry of Environment would have achieved its goal.
However, caution is advised with percentages purportedly indicating the impact of a singular component on the building's carbon footprint. Contrary to European standards, the Finnish calculation model for the building’s life cycle carbon emissions assumes that the emissions factor of grid electricity and district heating will improve in the future, which may very well prove unrealistic. It is easy to imagine a Swedish, Finnish, or Estonian government, putting an end to the current trend of sinking emissions of electricity. Should the scenario of steadily decreasing emissions not materialize, the percentages the Finnish calculation model is based on will cease to be true. It is often overlooked, that the emission factors of materials are also not constant, as the carbon emissions of electricity used in production also have an effect. Hence, the coefficients of the Finnish database of construction materials (5) should be updated, perhaps frequently, to begin with, should the emissions factor of electricity rapidly develop as predicted. A similar update is also needed for the limit values, that regulations have established for the maximum carbon footprint of various building types.
The type of foundation a building requires is bound to the conditions of the building site. The architect is not always in a position to decide the load-bearing material. In such cases, greenhouse gas emission limitations on materials lead to a situation, where the focus becomes not the choice of material but rather minimizing the amount of material used. The compact form of the heated part of the building thus promotes both energy and material efficiency.
Recent housing developments in Finland have been critiqued for focusing too much on financial gain. The core of the critiques is, that optimizing costs can easily lead to excessively deep buildings and apartments that only face one direction. In this case, construction costs, energy efficiency, and material carbon footprint all drive design in a similar direction. Good architecture, however, requires the possibility to utilize varied volumes. To counterbalance the fact that carbon footprint calculations favor compact designs, it would be useful to also similarly evaluate daylight conditions indoors, spatial flexibility, and other such factors which also influence the sustainability of a building, for instance by extending its lifespan.
The building’s carbon footprint turns a blind eye to the effects of occupancy rate. In terms of true climate impact, it matters if a housing block of 1000 square meters, i.e. the investment in energy and material required for its lifespan, offers a home for 25 or 50 people. The occupancy rate is, however, tabu since no one wishes to suggest limiting occupancy as a solution for the climate crisis.
Other factors which enable or restrict an eco-friendly lifestyle, such as building location, have not been included in carbon footprint calculations of buildings. There is a clear need for holistic evaluation on a regional level, taking into account the impact of land-use changes, location, and construction of necessary infrastructure.
The nature of decision-making in land-use planning may initially seem different to architectural design. Municipal urban planning leaves a lot of questions open. From a climate-change standpoint, however, the two scales of design are closely intertwined since land-use decisions may irreversibly fix certain decisions or enable the possibility for certain solutions, which may or may not be utilized at a later stage.
The challenges of regional climate goals
Cities are considered the pioneers in the fight against climate change. The city of Copenhagen's aim is to be the first carbon-neutral capital already by 2025 (6) and Helsinki strives for a similar goal by 2035 (7). In 2017, the president of Helsinki University, sustainability researcher Jari Niemelä, and Ph.D. student Karna Dahal showed that greenhouse gas emission calculation methods of various cities are not compatible (8): even the calculated results of Helsinki, Stockholm, and Copenhagen cannot be compared. So, when cities rush to declare their sustainability goals, we cannot precisely know what they are committing to.
Cities and regions typically evaluate greenhouse gas emissions territorially, where the limits of a region are mapped, and emissions produced within these limits are evaluated by sector. A similar approach is used in national inventories of greenhouse gas emissions.
The mere idea of a territorial analysis prevents the comparison of the calculations of various cities. For example, if several industrial buildings happen to be located within the limits of a given area, their energy consumption increases the greenhouse gas emissions of that chosen area, even if the production does not benefit the local inhabitants in any way. In another city, the amount of industry most likely differs or is located outside city limits.
Within the mobility sector, territorial analysis is equally problematic. All greenhouse gas emissions related to mobility are included in the territorial analysis. Hence, it includes a lot of the mobility of inhabitants, but not all, as inhabitants also move outside the limits of their home city. However, outsiders and transiting goods also travel through an examined region, the subsequent greenhouse gas emissions of which are included in the analysis.
Take, for example, the city of Riihimäki in southern Finland, a city of 30 000 inhabitants, located at a railway junction and along the nationally important Highway 3. If Riihimäki aims for carbon-neutrality (or climate-neutrality), it must in practice decrease greenhouse gas emissions and then compensate the remaining amount through a method of choice. Compensation can for example mean investment in a reforestation program or exporting emission-free energy. All compensation options incur a cost so greenhouse gas emissions must be cut as much as possible first.
If Riihimäki, like other cities, uses territorial analysis, the traffic on Highway 3 is also included in the total greenhouse gas emissions for the stretch that the motorway runs within city borders. Similarly, passenger and cargo traffic of the busy main railway line is also included in the emissions of Riihimäki for the section of the tracks that are located within the borders of Riihimäki. Riihimäki cannot influence the traffic on Highway 3 or the main railway traffic, but carbon-neutrality would require Riihimäki to compensate for also these emissions with the residents of Riihimäki paying for it. Territorial analysis clearly puts cities at an unequal footing in pursuit of carbon neutrality.
The territorially calculated greenhouse gas emissions of cities are commonly reported per inhabitant. This easily gives the impression that the conclusion is the carbon footprint per inhabitant of the city in question. The territorial calculation does not do this, as is quite evident from the previous description.
Examining consumption might be a useful tool to indicate carbon footprint per inhabitant. It includes all greenhouse gas emissions caused by the consumption of the inhabitants of a city – wherever in the world they are produced. This approach is recommended, for instance, by C40-cities committed to fighting climate change, and can produce very different results than territorial evaluation. In Finland, consumption-based studies conducted by Professor Seppo Junnila’s research team (9) led to a debate, which turned political, on the climate impact of urban densification in 2015. Consumption-based evaluation raises questions relating to lifestyle and consumption habits.
Climate strategies and redirecting urban development
Territorial analysis of greenhouse gas emissions is often based on the Greenhouse Gas Protocol guide for cites (10). It does not define calculation models, but rather advises on limitations and documentation. The model works better for evaluating realized emissions than as a design tool for future-orientated land-use planning. Designing the future requires a scenario approach, for which no instructions nor comprehensive protocol exists.
Greenhouse gas emissions of changes in land use are typically calculated with national greenhouse gas inventory methods recommended by the Intergovernmental Panel on Climate Change (IPCC), which is based on six land-use categories. This division, however, is far too crude to evaluate the land use within cities. The six land-use categories of the IPCC do not differentiate between green urban space and a treeless plot paved with asphalt, meaning that the method does not account for the climate impact of urban vegetation.
In pioneering cities, land-use planning typically aims to mitigate climate change by promoting urban densification and preventing urban sprawl. The city of Portland, for instance, sets a distinct limit, the urban growth boundary, for urban growth. All new construction is kept within this limit to densify the urban fabric. The cities of Minneapolis (11) and Hamburg, among others, have completely banned the zoning of new plots for detached houses, partly with the specific aim of densify the city.
When urban planning utilizes urban densification to prevent the use of natural areas for new construction and construction thus doesn’t require new infrastructures to be built, greenhouse gas emissions caused by changes in land use are avoided. As for transportation, the impact of densification is relevant only once proximity to services and public transport influence the daily kilometers traveled per person. Should greenhouse gas emissions of material production not be included in the calculations, as is often the case, the advantages of urban densification are only partially recognized; this kind of calculations entirely omit the climate impact (a spike in carbon emissions (12)) caused by the construction of new infrastructures (such as roads, and water and sewage systems).
It is, then, possible to decrease the climate impact of cities using measures that encourage denser urban development. The climate strategies cities draw up, however, also typically include many measures, which do not fall within the scope of land-use decision-making. Many measures are in fact outside the realm of what the city can control. The transition to electrically powered traffic, for instance, depends on decisions made by operators, car manufacturers, the state, and the EU. Have cities promised too much or have they chosen a calculation method ill-suited to measure their climate commitments?
Measure what can be measured
The words "Measure what can be measured, and make measurable what cannot be measured." are often attributed to Galileo Galilei. According to historians, the father of modern science thankfully never blurted out anything so foolish. The compulsive need to measure qualitative factors of the built environment is one of the fundamental problems of evaluating sustainability.
However, climate change is a problem that requires quantitative assessment to be resolved. Within our profession, we can promote scientific knowledge by making sure quantitative evaluation is always transparent and understandable, and by keeping architectural quality and quantitative evaluation of climate impact separate - and, on the other hand, by having an open discussion on the benefits, shortcomings, and blind spots of various calculation models.
1 Architects Declare Finland, 2020. https://fi.architectsdeclare.com/
2 Architects Climate Action Finland Network, 2021. https://www.acan.fi/
3 Synergia -toimistotalon kilpailu [Architectural competition for Synergia office building], 2010. Finnish Environment Institute and Pöyry Building Services Ltd. https://www.syke.fi/fi-FI/Tutkimus__kehittaminen/Tutkimus_ja_kehittamishankkeet/Hankkeet/Ekotehokas_toimitalo__pilottihanke_passiivitoimitalon_energiaratkaisuista_ja_niiden_ekotehokkuudesta
4 Verkkosaaren vähähiilisen viherkorttelin tontinluovutuskilpailu [Architectural competition for low-carbon green city block in Verkkosaari, Helsinki], 2021. https://www.safa.fi/kilpailu/verkkosaaren-vahahiilinen-virherkilpailu-tontinluovutus/
5 Finnish Emissions database for construction www.co2data.fi
6 CPH2025 Climate plan. A green, smart and carbon neutral city. 2012.
7 The Carbon-neutral Helsinki 2035. Action Plan. 2018. Publications of the Central Administration of the City of Helsinki 2018:4.
8 Dahal, K.; Niemelä, J. 2017. Cities’ Greenhouse Gas Accounting Methods: A Study of Helsinki, Stockholm, and Copenhagen. Climate 2017, 5, 31.
9 e.g. Heinonen, J.; Junnila, S. 2011. Implications of urban structure on carbon consumption in metropolitan areas. Environmental Research Letters. Vol.6. 98.
10 Global Protocol for Community-Scale Greenhouse Gas Emission Inventories. An Accounting and Reporting Standard for Cities. Greenhouse Gas Protocol. World Resources Institute, C40 Cities, ICLEI.
11 Kahlenberg, R. D. 2019. How Minneapolis Ended Single-Family Zoning. Rights & Justice Report. The Century Foundation.
12 e.g. Säynäjoki, A.; Heinonen, J.; Junnila, S. 2012. A Scenario analysis of the life cycle greenhouse gas emissions of a new residential area. Environmental Research Letters. Vol.7. 1-10.
