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Watts in store?July 2018

Written by John Piggot, Director, JPEC

BSRIA has published a guide to energy storage in buildings and campuses, which provides an illustrated overview of the many technology options including thermal and electrical energy storage systems.

The way in which we generate, store and use energy is evolving rapidly. Renewables now make up 30% of energy generation in the UK, with their contribution having increased twenty-fold since 1990. Regulations for new building energy efficiency are stricter than ever. Smart controls and the Internet of Things mean that we can exercise a level of control over our energy consumption that would have been hard to imagine 20 years ago. Until recently though, our ability to efficiently store energy was limited. This meant that we were unable to rely entirely on renewables, because they don’t always produce energy at the time that we need it.

That situation is changing rapidly, and building designers, managers and occupiers now have a wide range of technical options available to allow them to store energy. Batteries, thermal stores and phase change materials can be used individually or in combination. They all have their pros and cons and their usefulness sometimes depends on what combination is used. As new products emerge, design conventions are being challenged, but how can we navigate this new landscape?

Launch of BG 73/2018

The good news is that help is at hand; the new BSRIA guide BG 73/2018, Energy Storage in Buildings, provides an illustrated overview of the many technology options including thermal and electrical energy storage systems. The guide discusses the attributes of the various systems and their suitability in different applications. It is aimed at designers, facilities managers and occupiers who may be involved in new builds, refurbishment projects or day to day building operations.

For example; over recent years, batteries have got smaller, cheaper and more efficient, but there are many different types of battery available, offering different advantages. Electric vehicles typically use lithium-ion batteries, which are light and efficient, but highly flammable. After a few years of use, the performance of the battery in an electric vehicle degrades to the point where it needs to be replaced. The same battery can have a “second life” in a building, where its performance is still good enough for a less demanding application.

To be able to effectively re-engineer a battery in this way, its characteristics need to be understood; how well it recharges, whether it copes with being completely exhausted between recharges, and how long it will last.

Changes in heat storage

Thermal storage in buildings is also changing; as new buildings are better insulated, the demand for heating reduces, to the point where hot water for washing becomes the dominant heat demand. As more buildings connect to heat networks, the way in which heat is stored in buildings is also evolving. Maintaining suitable flow and return temperatures is critical when designing building services that will be connected to a network. The new BSRIA guide talks through these and other issues.

There are many advantages and financial incentives to the use of energy storage in buildings. These include:

  • Avoiding times of day with the most expensive energy prices;
  • Reducing short term peaks in demand so that building services can cope better;
  • Balancing sudden fluctuations in the local electricity network;
  • Providing standby power for essential equipment. The author wishes to apologise for the fact that the headline pun for this article is misleading. Of course, power is measured in Watts, whereas energy is measured in Joules.