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In terms CO2 emissions, is it better to repair or build a new one?

Reducing carbon dioxide emissions is a very important challenge for humanity. In our previous article, we looked at the emissions of the entire real estate sector. According to IEA, the building and construction sector accounted for 36 percent of energy end use and 39 percent of energy and process-related carbon dioxide (CO2) emissions in 2018, of which 11 percent was caused by the manufacturing of building materials and products such as steel, cement and glass.


Preservation Green Lab presented in a 2012 study that new building construction produces almost 50% more carbon dioxide emissions than repairing a similar old building. This is largely because building a new building requires manufacturing and transporting new materials, while repairing an old building uses existing materials. Even if the new building is 30% more energy efficient than the old one, it may take decades before the savings overtake the emissions during construction.



The difference in life cycle emissions can be significant. During the building's life cycle, most of the carbon dioxide emissions are generated during its use, not during the construction phase. If an old building is very energy-inefficient, its lifetime emissions may be higher than a new, energy-efficient building. This is because an inefficient building consumes more energy for heating, cooling and lighting. If the old building is very energy-inefficient and updating it to current standards requires significant changes, it may be better for the environment to build a new, energy-efficient building.


Location and infrastructure also influence the decision to repair or build a new one. If the old building is located in an area with insufficient infrastructure or few services, building a new one in a better location may be a better option. The new building can be designed in such a way that it makes better use of public transport, reduces the need for driving and thus reduces carbon dioxide emissions.


Determining costs is often not simple, especially when talking about life cycle costs. Life cycle costs include the building's maintenance, repair and energy costs throughout its lifetime. It is important to note that each case is unique. Estimating costs requires detailed budgeting and planning and may require professional assistance.


When considering the general population growth or migration of the area in question, new construction may be necessary to meet the growing demand. On the other hand, in densely populated areas such as cities, new construction can be challenging due to limited space and high land costs. In this context, repairing and renovating old buildings can be an effective way to increase housing capacity and improve energy efficiency. Probably, the structures of the old buildings do not allow significant additional living quarters and strengthening the structures may be very expensive. In this case, if the building permit allows it, the new building can take significantly more living space from the lot.


In conclusion, based on the available sources, it is often better to repair and renew the old than to build a new one, in terms of carbon dioxide emissions. This is because new construction requires significant new materials and energy, which produces large carbon dioxide emissions. Repairing and updating an old building can significantly reduce these emissions. However, the situation and the calculation may change in the next few years, when the production of low-carbon steel and concrete can be properly started.

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