Do we all have to become power producers?

The sun doesn’t shine on your roof alone

Buildings account for about one third of the world’s energy consumption. This share is likely to grow in the coming decades. This fact, combined with the idea that buildings should be conceived to last for a very long time, stimulated the World Business Council for Sustainable Development (WBCSD) to focus on zero-energy buildings. The aim of their Energy Efficiency in Buildings (EEB) initiative is to draw a roadmap to 'a world in which buildings consume zero net energy'.

But while it is easy to agree on the idea that houses and their appliances should evolve towards higher energy efficiency, one needs to ask why zero-energy buildings should be a goal in itself. Buildings are only one link in the overall electrical system chain. It is the impact of entire system that needs to be minimized, not just one link. From this perspective, domestic electricity production has mixed blessings.

As discussed in a recent blog post (How distributed should our power utilities be?), the sheer economies of scale often make centralized electricity production more efficient. On the other hand however, domestic production can in some cases lower the energy losses of transmission and distribution. But this is only true if the capacity factor of the installation is high enough.

People want energy, not energy systems

Another question one could ask is whether a majority of home owners are ready to operate their own renewable energy system. It is easy to find a small, vocal, and enthusiastic group of early adopters for domestic renewables, all eager to become more independent from their energy supplier. This evolution on its face seems to have advantages for both the environment and the free market, since more energy producers means more competition.

But turning domestic renewable energy into a mass trend is not so easy. People who are not well-grounded in technology prefer to buy energy, not an energy system. Conversely, if the task of operating and maintaining the systems is given to utility companies, such companies prefer centralized units instead of scattered, random users.

Solar roofs not sufficient in cities

A last consideration is whether houses and buildings are always the most appropriate place for installing renewable energy systems. Photovoltaic panels on a roof in most cases have a low aesthetic impact. But in the case of historic or classified buildings, even this small impact can already be too much. The Wall Street Journal reports that solar panels have been refused by many historic district regulators in the U.S. Moreover, roof surfaces in city centres are usually small in relation to the number of floors that must be served, making it difficult to attain a zero-energy building by a photovoltaic system alone.

Domestic wind turbines are aesthetically questionable

The aesthetic impact is even greater when you add wind turbines to the mix. Small wind turbines for domestic use have been developed, but one must question their advantage compared to large wind farms set in more remote areas. With built areas in Europe and North-America slowly but steadily getting rid of overhead lines and television aerials, it may be a tough sell indeed to replace one form of visual pollution with another, i.e. domestic wind turbines. The problem is compounded by the fact that these small wind turbines are expensive and have a very small output that rarely suffices for all the needs of one household. Consequently, creating zero energy buildings relying substantially on wind energy may prove to be appropriate only on well located agricultural land or industrial estates.

Buying green electricity

In the end, when a reduction of greenhouse gas emissions is the primary goal, why focus merely on what is feasible inside the boundary of a single building? In many cases, energy efficiency, solar hot water, PV systems, and heat pumps can bring houses close to zero energy. But if that is too difficult for economic, technical, aesthetic, or social reasons, going green by buying electricity from renewable energy farms elsewhere should be considered just as good. As long, of course, as this 'green electricity' is not a 'greenwash'.

References

• Article 'Should I put a windmill on my house to save the planet?' on articleheaven

• Article 'The "Zero Net Energy" Challenge' on Planet 25 NewsNetwork