la maison intelligente sera green ...


Donald Trump may have pulled his country out of the Paris Agreement but that doesn’t mean the entire United States has simply given up on sustainable development. Following the withdrawal of the Federal Government from the international climate accords, a number of US states have shown no hesitation in taking up the baton.  Accordingly, California’s state legislature recently became the very first to pass an ambitious bill which requires solar panels to be installed on every new-build house. Several towns in the Golden State had already made it mandatory to install solar panels on certain types of new residential property, while others have made commitments to use clean energy sources for their entire energy needs.  Meanwhile other states, such as New Jersey and Massachusetts, plus municipal authorities, including Washington DC, are contemplating drafting new legislation designed to ensure that all newly constructed buildings are able to install solar panels.


Californian technology serving the planet

  • 14 Feb
  • 10 min

However, the new legislation passed by the Golden State is by far the most ambitious ever drafted on US soil, requiring that every new house must be equipped with two to three kilowatts of installed solar power generation capacity, depending on the size of the property. This could be a system installed at each individual house or shared with other residences in the same street, terrace or block. This legislative measure is intended to enable California to attain the targets set for renewable energy use, namely that half of all electricity consumption in the state should be generated form carbon-free sources by 2030. The Golden State is already out in front in the US in terms of solar power, which currently covers over 16% of all electricity requirements, with an industry employing 86,000 people. Given that an average of 80,000 new residences are built every year, the new law is likely to help boost these figures considerably.

It is also quite likely that other parts of the United States will follow suit with similar legislation. Several times in the past, California has pioneered the way with environmental standards designed to reduce vehicle emissions and improve the performance of refrigerators, which were then taken up across the rest of the country. The Golden State may well create a precedent here once again with renewable energy, especially as the new law is very much in sync with a current major trend in both the US and Europe – the Autonomous House, which generates its own power. A growing number of households are attracted by the prospect of meeting their own energy needs, both from a financial perspective – reducing their energy bills – and a lifestyle point of view, as part of a widespread ‘Do it yourself’ movement.

... and autonomous

panneau solaire

The advent of the Autonomous House

Numerous initiatives are now underway with a view to meeting this demand. Multinational energy-sector firm Eaton has teamed up with automobile manufacturer Nissan to promote the concept of an autonomous house capable of producing and storing its own energy using the xStorage Home battery. Back in California, research students at the University of Berkeley have designed, in partnership with carmaker Honda, the Honda Smart Home, a residence capable of generating power from solar panels and using adapted vehicle batteries to store the surplus electricity for use during sunless periods.

Meanwhile, architects in Melbourne have built a prefabricated house designed to optimise energy use and go beyond self-sufficiency into surplus power production.  The Carbon Positive House relies on solar panels to capture energy, uses double-glazing and specially-designed walls to ensure excellent insulation and provides optimal light incidence so as to cut down on artificial lighting needs. Last but not least, the surplus heat drawn from the sun is channelled to heat water for domestic use.

Today France, with just 40,000 energy-self-sufficient households, lags neighbouring countries such as Italy, which boasts 630,000 homes producing their own power, the UK, which has 750,000 and Germany with 1.5 million. This lag in take-up is due to the characteristics of the French electricity system, which is based on a highly centralised grid that is highly dependent on nuclear power. However, there is some momentum in the market, and a more conducive legislative package was adopted last year, including such measures as tax-breaks for investment in this domain and the establishment of a fixed tariff for sales of surplus power sold to the grid, all of which points to a sizeable development on the energy self-sufficiency front over the next few years.  Some sources predict that France could well have four million energy-self-sufficient homes by 2030.

A greener future

maison autonome


Storage: the vital factor

While the regulatory framework undoubtedly has an important role to play in fostering the development of the Autonomous House, advances on the technology front are key.  Falling prices for photovoltaic equipment, the recent availability of wind-power installations specially designed for individual needs, and the advent of batteries capable of storing the surplus power generated by this equipment are injecting momentum into the market. The storage issue is in fact vital, as progress here will enable energy reserves to be built up when the meteorological conditions are propitious – i.e. windy or sunny weather – and drawn down when needed.

With an efficient energy storage system, a household would be able to store the surplus power produced by the house’s solar panels during the day and use it to meet the family’s energy needs during the night and then begin generating electricity from the sun again the next day. Ravi Manghani, an analyst at GTM Research, a consultancy firm specialising in the electricity industry, points out that the desire to store electricity first arose in the 1970s, but that only very limited progress was made in this direction until the early 2000s. Since then, a growing appetite for renewable energies, coupled with advances in both solar panel and lithium ion battery technology have prompted various companies to develop batteries designed to enable individual households to store their own energy.  

Regard d'expert

Russel Tencer

CEO de United Wind

Energy storage was for a long time held back by prohibitive costs, but over the last five years, costs have diminished considerably, so that storage is now starting to make sense from an economic point of view.  

Energy storage was for a long time held back by prohibitive costs, but over the last five years, costs have diminished considerably, so that storage is now starting to make sense from an economic point of view,” argues Russell Tencer, founder and CEO of United Wind, a US company that specialises in selling small wind-power installations aimed at individual home-owners. The company will, in return for a monthly fee, install, operate and maintain wind-power generation equipment at their property. United Wind is currently looking to link up with energy storage specialists because this is the area that will determine the success of the entire approach. “The falling cost of renewable energies is leading to a rise in their popularity, but if you want to reach 100% clean energy, storage must also be part of the equation,” underlines Vic Shao, Chairman of ENGIE Storage, a company that specialises in storing power from renewable energy sources.

Tesla pulled off a notable coup in 2015 with the launch of its Powerwall storage battery aimed at the general householder. Elon Musk’s company has set out to enable ordinary people to build their own individual energy-sufficient environment by, for instance, storing solar-generated electricity during the day so as to charge their Tesla car up in the evening. The company has also built in the Nevada desert  the largest battery manufacturing plant in the world, aptly named the Gigafactory; has supplied the Hawaiian island of Kauai with batteries to enable it to develop its own photovoltaic farm; and pulled off a nifty publicity stunt by manufacturing in record time a giant battery for Australia, which enabled a drastic reduction in the local cost of electricity. 

The self-sufficient house



Towards a decentralised energy market via the Blockchain 


Blockchain-Energy affinity just warming up

  • 22 Feb
  • 10 min

Household energy sufficiency not only enables families to increase their independence and reduce their energy bills: this revolution in progress also prompts us to re-think the entire energy ecosystem. Rather than being based on large power plants serving a central grid, electricity generation could become predominantly decentralised and distributed through a network of small installations based on solar and wind-power.  Vic Shao argues that this kind of system would not only be more environmentally friendly but also more resilient, especially in the event of a natural disaster. “Last year, when several hurricanes raged through the Caribbean and fires spread along the West Coast, local power grids were seriously damaged. If the system had been more decentralised, there would have been much less damage because you wouldn’t have had a central point of failure,” he explains.

Moreover, an approach based on self-production of energy enables us to rethink the way the energy market works, especially in the light of another recently-developed technology – the Blockchain. Using this transparent, decentralised database, it becomes feasible for households to sell any surplus clean energy they produce to anyone who needs it.  As a corollary, this also shows that there are other ways of drawing on renewable sources of energy than installing solar panels or a mini-windmill at your home. Those unable to do so, either due to a lack of financial resources or because they do not actually own their home, may nevertheless be able to back the use of green energy by purchasing electricity direct from green power producers.

Blockchain the future of energy?

blockchain energy

This new approach is made possible by so-called ‘smart contracts’ – IT protocols coded into the Blockchain that provide for a given action to be unleashed once certain precise conditions have been met. This enables secure transactions between individual parties to be implemented on the Internet, without the need for a third party to guarantee the security of the transaction. Add to this the use of tokens – digital assets which serve as currency for transactions carried out via the Blockchain, and we find ourselves with a genuine totally decentralised energy economy.

A number of companies – including SunContract, Enosi and WePower – have already launched themselves into this niche. As well as enabling smooth, secure and easy P2P trading at lower cost, the Blockchain offers a number of advantages when applied to the energy field.  The first is that the Blockchain provides an excellent way to promote the decentralisation of the energy sector. “Our solution offers a number of benefits to small power producers who wish to supply their community, by enabling them to compete with the larger players due to the lower cost of acquiring customers, limited transaction costs and better risk management,” claims Steve Hoy, CEO of Enosi, in US business magazine VentureBeat. The Blockchain is a transparent tool which provides a means of tracing back the various links in the value chain so as to ensure that the power being sold is genuinely ‘clean’.  One can envisage, for instance, Green Energy certificates being allocated on the Blockchain rather than having to go through a more onerous on-paper procedure. Last but not least, the Blockchain makes possible new ways of financing renewable energy projects by raising funds in digital currencies. An example of this is the WePower site, which enables green energy producers to raise funds in tokens against their future power output.

By Guillaume Renouard