ASHRAE Journal - December 2019 - 63

COLUMN EMERGING TECHNOLOGIES

solutions where buildings and the grid operate as a
single system.

PHOTO 3 Powerhouse Brattøra in Trondheim, Norway is an excellent example of a
building that showcases integration and interoperability.

Energy storage can help optimize buildings' use of
electrical and thermal energy, in addition to making
it possible for buildings to use more renewable energy
whether or not the renewable energy generation is
occurring when the building needs the energy. Storage
is one way to help make buildings ﬂexible so that the
building loads align with the changing needs of the
energy systems serving the buildings.
As we shift into thinking about making buildings more
ﬂexible so they behave like electric energy storage or
thermal energy storage systems, we should keep in mind
that electrical energy storage is something that the grid
already understands and knows how to value, and that
incorporating thermal storage systems for buildings is a
well-understood strategy. There are several challenges
on the building side that need to be addressed, including the fact that buildings cannot be simple batteries
with energy capacities because building load proﬁles
change over time.
Energy storage-speciﬁcally electrical energy storage-
brings cybersecurity to the table as a prominent challenge. Cybersecurity is something buildings will have
to account for and will undoubtedly be an area where
there will always be vulnerabilities. This means we have
to start thinking differently about how building control
systems are designed to ensure both the building and its
occupants are secure and ensure the grid is protected
from security breaches through building systems.

Energy Storage: The Questions We Should Be Asking
What Are the Reasons for a Building to Integrate Electrical Energy Storage?
Battery technology is improving, and economies of
scale are contributing to a downward trend in cost
(Figure 1).5 There is also an aspect of resiliency that
interests both consumers and utilities. For example, if
a building can ride out a power outage, then the building is accommodating its occupants. For some consumers and utilities, greenhouse gases are a strong enough
driver to start looking for a change.

What Are the Greatest Challenges Facing Thermal Energy Storage?

While battery storage will allow us to store electrical energy from renewables, thermal energy storage

PHOTO: SNØHETTA

Energy Storage: The Power of Space, Temperature, and Time

can help level energy loads in buildings. Water and ice
thermal storage is well understood, while new storage technologies are emerging (eutectics, and so on).
Traditionally, the economics of thermal storage have
been driven by rebates and time-of-use rates. Going
forward, there needs to be a more integrated and stable
approach to allow long-term planning. Integrating thermal storage operation with short-term grid load proﬁles
is the key to improving energy use while delivering
resiliency-research is needed to understand what the
planning parameters are and over what window of time
they are reliable, and then the research results need to
be packaged into clear applications for building design
professionals as well as building and grid operators.

Integration and Interoperability: Bringing it All Together
We are starting to see the emergence of the building-to-grid phenomenon as more and more smart
homes and interconnected buildings are developed.
This also means that controls and integration are
becoming even more critical to building a gridfriendly building.
A great example of a building that showcases
integration and interoperability is the Powerhouse
Brattøra in Trondheim, Norway (Photo 3). It encompasses all the key factors of a futuristic, grid-integrated building. The building's geothermal heat
pump system generates more heat than it needs so
it can share excess heat with other nearby buildings. The on-site photovoltaic system capacity is large
enough that it can charge 200 electric vehicles a day
and generate two times as much energy as it consumes. All systems within the Powerhouse Brattøra
building are digitally integrated, helping to make this
building the world's northernmost energy-positive
building.6
D E C E M B E R 2 0 19

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ASHRAE Journal - December 2019

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