Existing buildings: Effort to be climate neutral

Dr. Ernesto Garnier is CEO and founder of One Hundred Energy. (Image: ONE HUNDRED)

The federal government has just had to improve the legislation. Climate neutrality should now be achieved in Germany by 2045. Buildings play an important role here, as heating and electricity account for up to 35 percent of total Germany-wide energy consumption. However, we will not be able to demolish most of the buildings and build new ones by 2045, especially since this would result in a lot more CO2. Therefore, in addition to the question of how we can make greater use of renewable energies, in particular the question of how we can substantially increase the energy efficiency of existing buildings. “Efficiency first”, the focus on energy efficiency, is the central pillar in achieving the Paris climate targets. Due to the very large number of properties compared to new buildings, the existing portfolio is a strong focus of politics.

Prof. Dr. Claudia Nagel speaks about this in an interview with the founder and managing director of One Hundred Energy, Dr. Ernesto Garnier, about the achievability of the goals, the possible contribution of his company and the challenges in the building stock as well as the question of what can make the stock more sustainable.

Mr. Garnier, what do you think is a climate-neutral building?

Climate neutrality can be divided into the areas of construction and operation. Inventory management is primarily about operation. Most buildings initially built up a CO2 mortgage through construction. In operation, climate-neutral means considering the entire energy supply, i.e. that heat, electricity and mobility are entirely CO2-free. This explicitly includes the electricity consumption of tenants and residents. Current key figures and parameters such as energy consumption per square meter are not sufficient for a correct evaluation of the CO2 balance.

Do you see the federal government’s one-sided focus on “efficiency first” as expedient? What other strategies can there be, keyword: building as a power plant?

You shouldn’t play efficiency against power generation, you need both. Firstly: efficiency through the shift in heating from gas or even oil to electricity through heat pumps and innovative heating panels in the apartments. This requires innovative providers and strong incentives for retrofitting. Second: Large-scale photovoltaic rollout in the tenant electricity model. The advantage of the tenant electricity model is that in addition to sustainable electricity from PV, the rest of the electricity drawn from the grid is usually green electricity. Third: Transparency for the consumer and thus the opportunity to control one’s own energy consumption.

In your opinion, which instruments and incentives can lead to a more energy-efficient building? When is it worth saving CO2?

Buildings as energy producers

Buildings are often energy guzzlers. But there is another way: there are already properties that function as small-scale power plants and produce enough energy for themselves and their surroundings.

The contribution “2050: Every building is a power plant?“read in the current issue 6-2021 of our print magazine.

As an absolute priority in all legislation, the primary energy factor (including the primary energy factors for types of heating) must be replaced by the CO2 factor, including the total electricity consumption of the buildings, including utility units, in addition to heat. This is also the approach of the EU taxonomy, but it does not yet apply in the German Building Energy Act. This means that German real estate companies run the risk of focusing on regulation that will soon be obsolete. The CO2 price must then apply across the board for electricity and heat, so that optimization is possible across all sectors. And above all: The CO2 price must rise faster and more clearly to over 50 euros and, in the medium term, develop more in the direction of the real costs of over 100 euros. This means that the switch to the heat pump quickly becomes economical. In a next step, the CO2 mortgage of the existing buildings, which arose through the construction with cement et cetera, should be viewed analogously to a capex, which must firstly be minimized in renovations and new buildings and secondly over the lifetime through climate positivity – instead of climate neutrality is to be repaid.

In the building sector, the energy-efficient renovation is carried out by the landlord and the tenant benefits from the reduction in the costs for heat supply, i.e. the classic investor-user dilemma. How do we achieve a fairer distribution?

The best solution is an all-in warm rental model including electricity and heat. Sweden has something like that. Then the entire turnover, Opex and Capex, lies directly with the landlord and he can optimize himself through concepts such as tenant electricity or heating renovation. It is of course important that there should not be an unlimited rent increase here either, but that there are, for example, efficiency benchmarks for the heating and electricity rates applied. It is also interesting that the landlord benefits when he motivates the tenant to save energy. Climate and landlords are then in the same boat.

There is no sustainability without digitization. From my point of view, the energy transition cannot succeed without the contribution of digitization. In your opinion, what role do digital solutions play?

A remotely read, high-frequency recording of measured values ​​for electricity, heat and water is the basis for an efficient supply of the building and for a real CO2 balance. Here, deregulation must be carried out as quickly as possible and the smart meter rollout simplified so that measured value IoT becomes the standard in existing buildings. In addition to deregulation, there is an obligation to release the broadband connections of telcos in the technical rooms of buildings for the use of IoT players. In this way, the building itself can be digitized more quickly. It is also crucial that PV, smart meters, heat pumps, charging stations, etc. are actually installed at high speed. After that, digitization can help with optimization. In order for the expansion to take place, there is an urgent need to reduce bureaucracy and deregulation at the level of the distribution network operator, with the laws (EEG, heating costs ordinance, …) and an absolute focus on the issue of CO2 when it comes to incentives and rules.

At the end a request concert for you: What has to change in politics so that I can fulfill your vision?

  • Building Energy Act based entirely on CO2 (electricity and heat incl. Households) with milestones 2030 and 2035 as well as the goal of CO2 = 0 by 2045, open to technology
  • Warm rental model including electricity, heat and CO2 responsibility at the landlord
  • 1-to-1 implementation of the European requirements in German laws (e.g. Energy Efficiency Directive), without complicating and installing pitfalls
  • Reduction of bureaucracy and nationwide standardization of the reporting processes and accounting processes for PV and smart metering and e-mobility vis-à-vis the distribution network operator. The best way is to use digital interfaces via the Federal Network Agency
  • Solar requirement in new buildings and roof renovation
  • Smart metering is compulsory and simplified rules for cost reduction and technology openness


Prof. Dr. Claudia Nagel (Bild: High Rise Ventures)

The interview was conducted by Prof. Dr. Claudia Nagel, Managing Director at High Rise Ventures, a company builder in the real estate sector.


Are you interested in our print magazine?

You can find an overview of all subscriptions here.

You can also order individual issues through our customer service:

+49 (0)6123 9238 276

– .

Read more:  The University of Córdoba will monitor students with dyslexia through artificial intelligence

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Recent News

Editor's Pick