When it comes to eco-friendly building, there is no universal standard. Each country has different laws and regulations, which continue to evolve as technological innovations open up new possibilities. Summing up the main guidelines to date, the World Green Building Council offers a list of criteria for “green” homes:

• efficient use of energy, water, and other resources

• use of renewable energy (f. ex. solar systems)

• measures to reduce pollution and waste production through re-use and recycling

• good indoor air quality

• use of non-toxic, natural materials

• a design that takes both the environment and the occupants’ quality of life into consideration

• a design that can be adapted to a changing environment

Depending on how many of these criteria are met, we can distinguish different types of energy-efficient buildings – from “passive” to fully self-sustainable homes:

When it comes to eco-friendly building, there is no universal standard. Each country has different laws and regulations, which continue to evolve as technological innovations open up new possibilities. Summing up the main guidelines to date, the World Green Building Council offers a list of criteria for “green” homes:

• efficient use of energy, water, and other resources

• use of renewable energy (f. ex. solar systems)

• measures to reduce pollution and waste production through re-use and recycling

• good indoor air quality

• use of non-toxic, natural materials

• a design that takes both the environment and the occupants’ quality of life into consideration

• a design that can be adapted to a changing environment

Depending on how many of these criteria are met, we can distinguish different types of energy-efficient buildings – from “passive” to fully self-sustainable homes:

• Passive houses obtain the energy needed for heating from renewable resources, i. e. sunlight and thermal recovery. This only works if the household runs on not more than 15 kilowatt hours (kWh) per year and square metre – including temperature regulation, hot water, and electricity. Passive systems are rather difficult to retrofit and thus recommended for new builds.

• So-called zero-energy homes derive their name from their annual balance sheet: any energy consumed by the building must also be produced by the building. To that end, net-zero houses rely on renewable resources on site.

• Plus-energy homes, on the other hand, produce even more energy than they consume per year. The remaining surplus can either be transmitted into the public power grid or used for private purposes.

• By definition, self-sustainable homes are economically independent and equipped to provide for their own needs. They produce energy directly on site – as much as can be consumed and stored throughout the year. Solar and/or geo-thermal units serve to process hot water and run the heating system. A photovoltaic plant on the roof generates power that can be used for electromobility as well. Self-sustaining homes work without any connection to the local electricity grid. Their system is supported by clever facility management, smart building technology, and energy-efficient appliances.

You don’t necessarily have to buy or build something in order to make your surroundings eco-friendly. Apart from single-family houses, apartment complexes have also become the focus of many self-sustainable building projects:

• A block of 30 flats in Vårgårda, a small town in southern Sweden, is powered entirely by solar energy and stored hydrogen. The project has thus earned the title of “the world's first energy self-sufficient housing complex”. More than 150 flats in six housing blocks operate without external energy sources, leaving residents unaffected by fluctuating electricity prices. Solar panels on the rooftops alone produce enough to cover the power supply all year round.

• Similarly, a housing development on the Zurich Lake in Switzerland sets new standards for modern communal living. The so-called “Männedorf” generates the annual power supply for 16 families with the help of photovoltaic systems and two windmills. All residents have a monthly electricity budget free-of-charge, while an app helps to monitor their energy consumption.

There are many ways to reduce your energy consumption, even if you don’t live in a fully modernised house. For tenants, we recommend the following measures:

There are many ways to reduce your energy consumption, even if you don’t live in a fully modernised house. For tenants, we recommend the following measures:

• Check the energy certificate before moving into a new flat. This document contains information such as the resources used for heating or the Co2 emissions produced on average.

• Ask the lessor how the heating system operates and how it can be regulated. Indoor temperatures should not exceed 21 degrees Celsius in living areas and 18 degrees in bedrooms.

• If you want to turn a flat into a partly self-sustainable home, plug-in solar panels will do the trick: mounted at the right spot on your balcony, they can draw energy from sunlight and thus support your household.

• Instead of leaving your windows tilted, air your flat three to four times throughout the day. Otherwise, you will waste valuable energy.

• Poorly isolated flats oftentimes emit a lot of heat around windows. On bright days, you can utilize the sunlight to warm up the room. During the winter, closed blinds keep the cold from creeping inside.

• Older household appliances require a high amount of energy. Try to gradually replace them with modern, more efficient models.

• TVs, computers, or sound systems on standby mode are very power-consuming as well. You should turn all devices off whenever you don’t need them – switchable plug strips can be of great assistance in that regard.

• Got a tendency to leave the light on in empty rooms or hallways? Switches with smart sensors, such as the Gira Sensotec, ensure that your home will only be illuminated when (and where) necessary. Reacting to ambient movement, they turn lights on and off automatically.

• Even the bathroom offers many possibilities to spare valuable resources – with water-saving showerheads, valves, or toilet flushes.

• Smart installations such as the Gira System 3000 control lights, blinds, and heating automatically, which makes it easy to keep your energy consumption in check. They are suitable for both new self-sufficient homes and retrofittings in older buildings.

If you drive a car that doesn’t run on fossil fuels, you can set up your own charging station – a so-called wallbox. Mounted next to the parking spot, these devices recharge your vehicle’s battery with a capacity between 3.7 and 22 kilowatts. The energy needed can in turn be provided by a solar plant on your roof top – ideally with a buffer storage and a compatible app to monitor the system.