Around the globe, cities are growing. Today, they house 50 percent of the world’s population and are responsible for 75 percent of all energy consumption and 80 percent of carbon emissions. Reducing our cities’ environmental impact means taking a closer look at how their buildings use energy, particularly electricity, and what we can do to reduce that demand. The new international standard IEC 60364-8-1, “Electrical energy efficiency within low-voltage installations,” provides a framework for this effort, with useful guidance for both the designers of new buildings and owners of existing structures.
Released in November 2014, IEC 60364-8-1 isn’t a mandatory standard, but rather describes the state of the art in energy-efficient electrical design and operation. In this post, I’ll be providing an introduction to the document’s intent and implementation, focusing on the three overarching goals that guided its development (these are summarized in Figure 1):
- Minimize energy loses in the electrical installation
- Use energy at the right time, when it’s needed and at the lowest cost
- Maintain efficient performance over time
Minimize Energy Losses in the Electrical Installation
Decisions made when a building is initially designed or undergoing major renovations can have the biggest impact on its environmental and financial performance, because resulting energy savings accrue over the structure’s entire lifespan. This is why the new standard pays special attention to the following aspects of wiring design and installation:
- Voltage drop. Maximum voltage-drop recommendations are provided in Clause 525 of IEC 60634-5-52:2009.
- Conductor sizing. Increasing a conductor’s cross-sectional dimensions will reduce power losses, saving both energy use and costs over time. Designers should assess the cost of losses during the conductors’ working life against any initial additional cost due to oversizing. IEC 60287-3-2 offers a method for this calculation.
- Optimize main switchboard placement. Electrical designers should use the Barycenter method to optimize placement of the main switchboard (and transformer). This move improves the installation’s energy performance and can reduce initial cost by reducing the total length of cables/conductors.
Use Energy at the Right Time, When It’s Needed and at the Lowest Cost
This goal also is most easily implemented during a project’s design phase, but also could be part of an efficiency upgrade at other times during a building’s lifespan. Specifically, designers should:
- Optimize circuit design. Circuits should be defined/grouped with energy efficiency in mind.
- Control how electricity is used. Designers can reduce future electricity use by incorporating sensors and related controls in lighting, space-conditioning and other systems.
Maintain Building Performance
Even the highest-efficiency buildings become less efficient over time if owners aren’t vigilant in monitoring ongoing operations. A formal, continuous-improvement style efficiency program can ensure new buildings maintain their performance and can help bring existing facilities up to present-day standards over time. As illustrated in Figure 2, the essential requirement for such a plan is an understanding of current and ongoing electricity use through appropriate metering and monitoring equipment.
For more detailed guidance on the new IEC 60634-8-1, along with other IEC standards, you can download the new 2016 edition of the Electrical Installation Guide. And be sure to visit our Consulting Engineer Portal for a range of electrical design resources.