Page 41 - Energize May 2022

TECHNICAL

mandatory disclosure of building energy certificates. The majority of buildings do not employ energy metering beyond the mandatory
performance, in the form of building utility company meters.
energy performance certificates, which However, knowing how much energy a building uses and where it is being used is
indicate a building’s energy consumption essential to any strategy to reduce energy usage. Before the most effective energy reduction
2
per m per annum. effort can be determined, it is important to know how the building uses energy.
Building energy management is the Advanced metering systems can provide such information. Energy meters can be viewed
optimisation of energy usage, taking as analogous to a fitness tracker. Just as a fitness tracker does not directly improve one’s
the building management system (BMS) level of fitness, an energy meter will not directly lower the energy usage of a building. All an
objectives into account. BEMS is solely advanced energy meter can do is to indicate where energy is being wasted. This would help
about the efficient use of the energy planners evaluate to what extent energy reduction goals are being met.
needed to meet the building’s operational
requirements. Boosting energy efficiency
Things have changed, as buildings Energy efficiency measures also fall into two categories, passive and active. Passive energy
today not only consume electricity but efficiency measures simply avoid the unnecessary use of energy. One example of a passive
generate electricity as well. The use of energy efficiency measure is the replacement of incandescent lamps to energy-saving
rooftop and parking lots for PV systems, lighting technologies. Active energy efficiency is about controlling the use of energy. This
and onsite energy storage systems, has type of energy efficiency measure typically requires continuous monitoring, using power
changed the way a BEMS is configured. measurement devices and cloud-based or on-premises power monitoring software, together
The system must now meet demand by with active management, including an action plan and following up on results.
balancing energy drawn from the grid
with energy generated and stored locally. Incorporating renewable energy
It must simultaneously take the building To become neutral or positive with regard to energy consumption, it is sometimes
management system’s requirements necessary to integrate local energy sources. Several renewable technologies commercially
into account, as well as the price of grid available today can completely cover the consumption needs of most buildings. Consisting
electricity and demand management primarily of photovoltaic (PV) systems, however, these renewable technologies, provide
requirements. variable, intermittent energy supplies. To achieve the overall objective of mastering and
In addition, the building may be optimising energy use while also becoming more independent of the electrical grid, these
powered by a co-located microgrid, energy resources must be coupled with storage or other more stable electricity generation
where the renewable energy and storage technologies, such as gas engines or fuel cells.
components are part of a microgrid. In An important element of designing, constructing and managing green buildings is the
this case the BEMS needs to communicate use of control and optimisation solutions which play an important role in improving the way
and interact with the microgrid’s control energy is produced, consumed and stored.
system. The first layer of control, the BEMS, is key. Usually cloud-based, these systems are able to
forecast and optimise energy usage, leveraging onsite distributed energy resources to reduce
Energy management, metering and energy bills and better integrate renewables. In addition to a BEMS, a power management
monitoring system could be used to operate the system.
The heart of a BEMS system is data The aforementioned solutions are part of a larger green building ecosystem which
regarding the amount of energy could provide some of the most effective means to achieving a range of South Africa’s
consumed, where it is used, and more
recently, for what purpose it is used. Now,
in addition to knowing how much energy
was purchased from the grid and when
and what it cost, we also need to know
how much energy was generated onsite,
when it was generated, and how much of
it is in storage.

Metering standards
Some modern building standards specify
the level of metering required at different
points of consumption as well as overall
metering. There is no requirement for
in-depth energy metering in South
African buildings. All that is needed is
the gross energy consumption for energy Figure 2: The use of artificial intelligence in a building energy management system: IEA

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