Improving Energy Efficiency – Mar 23

Εnergy rating upgrades on renovation projects – Dinokratous 41 example

Hello everyone.

Nobody can argue against the view that the built environment and particularly real estate is responsible for a large proportion of carbon emissions. Big efforts (maybe not enough?) are being made in the construction techniques side, the material side and the real estate industry to mitigate these adverse impacts to the extend it is technologically and financially viable. A belief that is more and more heard is that one of the most efficient ways to improve the energy performance of our cities is to renovate the existing building stock, rather than knocking down and building up again.

This is due to the fact that when renovating, part of or the entire structure of a building can retained and the production and transportation of large amounts of cement and other carbon emitting materials, as well as other construction activities (e.g. digging for a new building’s foundations) are required at a much lower extent. In certain cases, additional features such as walls, floors and other internal parts of the building can also be preserved and thus not only saving in energy consumption and waste, but also protecting part of the original building character.

It goes without saying that as with all options, this choice is not without certain challenges that need to be addressed. Ensuring that certain buildings can be converted to the latest and highest energy efficiency standards, or that they can be upgraded to the most current health safety specifications, or that renovating a building is technically and financially the most efficient way forward.

With our most recent renovation project, Dinokratous 41, a 126 sqm, 3 bedroom apartment in Kolonaki, Athens, we hope that we can provide some proof of the energy efficiency improvements that can be achieved by simply renovating the internal area of an apartment. The apartment belongs to a 1976 building and was acquired in 2022 with an energy rating of Z, which is the one before last rating Energy Performance Certificate which is used by the Greek authorities. Following the works, the apartment was upgraded by four positions to an energy rating of B.


The key actions and improvements relating to the energy upgrade of Dinokratous 41 were:

  • Replacement of all windows and frames with new energy efficient, double walled insulated ones
  • Replacement of heating and water-heating systems from building common heating to independent natural gas boiler
  • Replacement of cooling systems with new, energy efficient, WiFi enabled air-condition units
  • Installation of smart, WiFi-enabled thermostat to ensure efficient heating usage
  • Installation of new, low-consumption appliances

These changes allowed us to exceed the maximum energy rating upgrade that was presented by the authorities in the original energy certificate by one grade (from a maximum of C to our achieved of B). Apart from the improved carbon footprint of the apartment, there will also be significant cost savings by the users as they will able to use less heating and cooling, they will have full control of their heating and cooling needs and will be able to control and precondition the temperatures of their spaces remotely.

Additional, mostly building-wide actions, such as thermal-insulation coating at the facade or installing photovoltaics or home wind turbines could improve energy efficiencies significantly further.

Our achievement is not the A+ rating that certain new-builts can achieve these days, however, if we consider the “invisible” energy costs of demolishing an existing building and the increased wastage of existing materials and production needs for new developments, renovating still feels like quite an attractive way to improve the energy footprint of our cities.

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To view Dinokratous 41, please click here.