The Solar Revolution in Buildings

Episode 2: Positive-Energy Buildings

The homes and buildings in which we live, work, and spend our time are undergoing a revolution. The buildings of tomorrow will bear little resemblance to those of today. Buildings are at the heart of a three-phase energy revolution: self-consumption, positive-energy, and thermal renovation. Let’s take a look at the second phase: positive-energy buildings.

Buildings represent a major energy and climate change challenge in an era of declining energy resources. Our houses, apartments, offices, and public buildings account for 30% to 40% of global energy consumption (International Energy Agency (IEA). And greenhouse gas emissions from buildings represent approximately 30% of global emissions according to the World Green Building Council.

When thinking about buildings, we need to include the energy that goes into producing and transporting construction materials and operating heating and cooling systems and appliances. The construction process and the many activities of a building’s occupants make up its energy history. Fossil fuels, the biggest issue according to the NetZero Foundation, are often used for heating and air conditioning, while appliances run on electricity.

“Great, unrealized potential”

If we do nothing, says the IEA, the building industry may increase its energy consumption by 50% by 2050. In emerging countries, new buildings are going up at a rapid pace, opening up lots of opportunities for designing sustainably. In industrialized countries the situation is somewhat different because new buildings are being added more slowly and represent only a fraction of the total building stock. Renovation is more of an issue in this case. According to the EU Science and Knowledge Hub, European buildings are on average 55 years old. So “there is a great unrealized potential for energy saving in the refurbishment sector, to which other key benefits are related: improvement in energy security, job creation, fuel poverty alleviation, improved indoor comfort, and increased property values.”

2020 objective for all new buildings

The European Union decided to address the new building issue back in 2010 with the nearly zero-energy building concept (nZEB).The directive on the energy performance of buildings introduces the principle that new buildings should be at least neutral in terms of greenhouse gas emissions by 2020.

The directive sets 2018 as a deadline for state- and government-owned buildings. European Union members subsequently have had to put national strategies in place that take living conditions, climate, resources, and local culture into account. For example, zero-energy buildings would not necessarily be designed in Poland the same way they would be in Portugal.

Controlling consumption and renewable energies

The European Union defines a “nearly zero-energy building” as having a “very high energy performance,” with “nearly zero or very low energy requirements covered to a very large extent by renewable energy sources, including energy produced onsite or in the vicinity.”

Where are we today? A number of organizations track developments in this market. In October 2016, the ZEBRA Project consortium, a group of academics, researchers, and consultants, released a comprehensive report on the nZEB market in 17 EU member states. The document stresses that Europeans need to better define what constitutes a nearly zero-energy building.

The market is ready

The ZEBRA Project reports rapid growth in the sector from 2010 to 2014 (year of the latest available data). The overall maturity indicator for the European nZEB market, on a scale of 0 to 1, rose from 0.08 in 2010 to 0.66 in 2014. If we look in more granular detail we can see that the market penetration criterion, which has seen substantial growth, still has lots of room to improve. The same can be said for the regulatory framework, with a score of “only” 0.52 in 2014. At the same time, availability of technical components required for the nZEB market is high (0.83), and the cost indicator even more so (0.94). So everything is in place for big growth, especially since it is becoming increasingly clear that nZEB construction increases property values: the score for this criterion rose from 0.38 to 0.74 from 2010 to 2014.

France and Denmark are two of the most mature markets in Europe whereas Luxembourg and Poland are last.

Growth in green buildings

Nearly zero-energy building projects are popping up everywhere, not only in Europe, but around the world. A Wikipedia article on the subject lists national and regional initiatives and some outstanding buildings worldwide.

The Pearl River Tower in Guangzhou, China boasts a spectacular design and engineering elements anticipated to reduce its energy consumption by 58% compared to a standard building the same size. The Edge is the Dutch flagship project. Named “the greenest building in the world” by the British rating agency BREEAM, it incorporates a wide range of innovations that enable it not only to do without fossil energy, but also to produce more electricity than it consumes through it use of solar panels.

In Munich, Germany, the NuOffice building, occupying 11,000 m², consumes a remarkably low 30 kwh per m² per year, or 90% less energy than standard buildings of the same type. The researchers at the Fraunhofer Institute for Building Physics (IBP) contributed to this project. Other projects worth mention are the Pixel Building in Melbourne, Australia, the Porter School of Environmental Studies Building in Tel Aviv, Israel, and the Indira Paryavaran Bhawan building in New Delhi, India.

A regularly updated database on European nZEB projects is available to the public. The French environment and energy management agency ADEME tracks growth in the positive-energy sector (BEPOS) with a database of over 430 projects built from 2000 to the present, from individual houses to office buildings.

What remains to be done

Of course we still have a long way to go. The nearly zero-energy/positive-energy building market is still in its infancy. The World Council reports that less that 1% of buildings worldwide, i.e., 500 shopping centers and 2,000 houses, fall into these two categories.

The good news is that costs have come down. Positive-energy buildings rely more on construction expertise and strict standards than technological innovation. It’s true that the addition of local production capacity (mainly solar) increases the apparent cost of construction. However, such energy systems can be self-financing over the long term, either through the sale of electricity back to the grid or through self-consumption. What’s more, if their construction costs are controlled and energy production is self-financing, zero- and positive-energy buildings can offer significantly better quality of life to occupants at the same cost as standard buildings. In the long term, property owners are likely to adopt the principle and tenants will prefer them to “old-fashioned” buildings.

See here the Episode 1: Self-consumption

See here the Episode 3: Thermal renovation