Page 40 - Energize May 2022

TECHNICAL

Building energy management:

Metering, monitoring and the

building energy performance gap

Buildings presently account for approximately 40% of the world’s energy consumption. Beyond energy
use, buildings also are responsible for 30 to 40% of all greenhouse gas emissions. With South Africa
facing rising urbanisation and population growth, building usage is likely to increase, and attention
needs to be paid to building-energy usage and management.

BY MIKE RYCROFT, ENERGIZE

uilding-energy management Green Star Ratings in South Africa.
systems (BEMS) have been in use Although the general framework and specific technical contents of these green building
Bfor decades and have advanced to standards are different, they have a common aim: to put an emphasis on the quantifiable
keep pace with demands such as energy performance of buildings. The objective of delivering a green building can only be achieved
management in the commercial building by ensuring that various performance issues of the building meet a set of predefined
sector and BEMS have to develop further requirements, and a green building is, to a large extent, a performance-based building.
to accommodate new demands. The performance of green buildings is a critical issue in both the design and occupation
In addition to the straightforward stage. In the design stage, the performance can be predicted through theoretical calculation
legacy commercial building, for which or experimental testing. In the occupation stage, it can be physically measured or
there are energy consumption standards, investigated through other means such as occupant surveying. To meet and maintain these
we now have green buildings, which need standards, an advanced BEMS is needed. Such a system could highlight and record areas
to meet environmental standards; smart where actual performance differs from the design values and could be used to correct or
buildings, which need to interact with the modify performance to improve efficiency.
grid and other connections; and net-zero Compliance with green building codes, however, does not necessarily guarantee
buildings, which must generate and store energy savings, and the building energy performance gap (EPG), which is the difference
energy, as well as exchange energy bi- between designed and achieved energy performance, is a well-known and well researched
directionally with the grid. phenomenon.
On top of this we now have a growing
focus on human-centric building design Building energy efficiency
and operation, which changes the meaning With the introduction of green building standards and legislated sustainability targets,
and focus of building efficiency. All of these the importance of building energy management systems has increased. In addition to
factors can cause a shift away from the the introduction of voluntary green building performance criteria ratings, we now have
classic goal of optimising the efficiency
of energy consuming components of the
building and require a reassessment and
redevelopment of the function of the BEMS.
Sustainability is considered by many
industries as the aim for development. In
the building sector, designing, constructing
and operating green buildings is a widely
accepted path to sustainability. This
trend is confirmed by the development
and implementation of green building
standards in many countries. Examples
include LEED in the US, BREEAM in the
UK, the Green Building Label in China, and Figure 1: An example of a Green Star Rated building: Solid Green Consulting

energize | May 2022 | 38