_Futurization
Authors: Daniel Böhm, Energy Expert at WAVESTONE and Felix Heimke, Energy Expert at WAVESTONE
Energy-efficient buildings are key to a successful energy transition. But what specifically can be done to implement sustainable energy concepts in the building sector? Gain insight into the tools and measures that improve the bottom line, how to build the right framework, and what a suc-cessful example looks like.
Sustainable building energy concepts are crucial for the environment
Buildings are massive energy guzzlers: they account for almost 40 percent of Europe’s overall ener-gy consumption, making them a major contributor to the rise in global CO2 emissions. This also means that one of the most effective tools for preventing greenhouse gas emissions is reducing the energy demand of buildings.
Politicians have recognized the importance of climate action: Germany has committed to being climate-neutral by 2045. Another aim is to reduce the primary energy demand of buildings by 80% by 2050.
40%
is the share that buildings have in Europe’s overall energy consumption
But it will require a massive shift toward more sustainable energy concepts in the building sector for us to reach these climate targets. Energy consumption and sustainability need to be central considerations both in the planning and construction of new buildings and in the modernization of existing buildings. But what are the specific actions that can and need to be taken to make our buildings more sustainable in the near future – and to make the energy transition a success?
The path to more sustainable energy concepts: two major tools
Two tools are crucial to reduce the energy consumption in the building sector and reduce CO2 emissions:
1. Transitioning from fossil to renewable energy sources
2. Sustained improvement in the energy efficiency of buildings
The building sector holds significant potential to achieve both.
Leveraging renewable energy for energy-efficient buildings
First, there are many opportunities for using renewable energies in the building sector. One im-portant aspect here it to choose local energy sources, with different approaches for urban and suburban areas. In addition, other sustainable energy sources can be used effectively in buildings.

Urban spaces: district heating & combined heat and power (CHP) heating networks
Urban areas are particularly suited for the use of district heating. It is highly scalable, making it an affordable and efficient solution for cities. The use of combined heat and power plants enables massive CO2 savings over conventional energy generation. Going forward, local CHP district heating networks using biogas or renewable hydrogen present another sustainable heat supply alternative in urban regions.

Suburban & rural spaces: heat pumps
In more rural areas, the use of heat pumps seems to be a particularly promising approach. Heat pumps collect heat from the air, ground, or water. All of this comes with enormous challenges: if we are to reduce CO2 emissions in line with climate targets, we will have to replace eleven million conventional fossil fuel-based heating systems with heat pumps over the next 30 years in Germany alone.
Legislators need to create incentives for switching to new heat energy sources in residential build-ings, which are often owned by private owners. However, non-residential buildings are just as cru-cial in the transition to renewable energy.

Leveraging sustainable energy sources
The use of other sustainable energy sources such as solar, wind, or bioenergy also helps reduce the energy footprint. According to the International Renewable Energy Agency (IRENA), solar power alone could account for over 13 percent of global electricity generation by 2030, just to give one example.
Solar power systems also play an important role in establishing decentralized building energy sys-tems. Particularly in combination with home battery systems, this technology is essential in the construction of fully energy self-sufficient buildings. These types of buildings combine photovoltaic systems and battery storage with an intelligent energy management system to operate power consumers, such as heat pump heating systems or electric cars, as efficiently and sustainably as possible.
Improving the energy efficiency of buildings
The second tool is to improve the energy efficiency of buildings through a combination of energy conservation measures. After all, the most environmentally friendly and cheapest energy is energy that is not consumed in the first place.
75%
of household energy
is consumed by space heating
Space heating accounts for around three quarters of total energy consumption in households. This means that in order to achieve our climate targets we need to pay special attention to the heat supply of buildings. Two factors in particular help reduce heat consumption:
1. Adding insulation to buildings in need of renovation
2. Modernizing and replacing heating systems in older buildings
The majority of existing houses in Germany were built at a time when they did not have to meet energy efficiency requirements. Today, for example, more than half of building exteriors alone have not been insulated yet. The renovation rate for existing buildings, however, still remains at around one percent only.
In order to achieve climate targets, it is essential to increase the rate of energy efficiency renovations to at least two percent going forward. For this to succeed, attractive investment conditions must be created for home owners in particular.
With its federal subsidy for efficient buildings (BEG), the German government is promoting various measures for the renovation of buildings that permanently save energy costs and thus protect the climate.
However, some of the subsidy programs, e.g. programs by German state-owned investment and development bank KfW, are currently suspended due to overwhelming demand (as of February 2022).
Other measures intended to make residential and non-residential buildings more energy efficient include:
- Airtight construction of buildings to counteract heat loss
- Heat recovery through ventilation systems
- Energy-optimized lighting systems, e.g. using motion detectors and timers
- Deployment of efficient cooling systems, e.g. in data centers
- Efficient building services and plant engineering, e.g. for indoor air, heating or electrical engineering

Actively managing energy efficiency in buildings
Measures to improve the energy efficiency of buildings are an important building block on the road to climate neutrality.
Legal framework for energy concepts for buildings
In an environment where legal questions regarding laws on energy efficiency, tenancy, construction and real estate converge, legislators are increasingly called upon to establish a suitable legal framework to strengthen innovative and sustainable energy concepts.
A first step in this direction is the Landlord-to-Tenant Electricity Act, which provides targeted subsi-dies for electricity that is generated and consumed. It allows housing developers and landlords to take part in a new business model and offer their tenants local, renewable electricity.
Another important regulation to promote sustainable and efficient building design is the Building Energy Act (GEG). The Building Energy Act, which went into effect in November 2020, is the first regulation to set a mandatory energy standard for buildings and define what a low-energy building is. Going forward, new buildings