ASHRAE Journal - July 2023 - 18

FEATURE
FIGURE 1 Annual US Energy Consumption for Commercial and Residential Buildings by Year.
25
20
15
10
5
1950
1960
1970
1980
1990
Year
Residential
2000
2010
is generated from fossil fuels. And remembering that
the biggest part of the energy pie is buildings shows the
importance of substantially reducing the energy that
buildings use in both new construction and retrofits.
If you look at the Energy Information Administration
data,1 you see a leveling off on how much energy
buildings are using in the United States (Figure 1). In a
flat scenario, we are building buildings at the same rate
that we are saving energy in existing buildings. If it is
going up, we are not keeping up and the energy pie will
continue to grow.
Overall, even if we talk about individual buildings
becoming more efficient, we must have a pretty substantial
reduction in energy to make this work. And so
how is that done? The first place is new buildings. It's a
blank slate, with lots of opportunity to really get energy
use intensity (EUI) down to 50% or less of what we kind
of consider normal code compliant buildings. The
ASHRAE Advanced Energy Design Guide 2 series covers this
topic and gives EUI targets that can really help consulting
engineers and designers.We also have good heat
pump technologies out there today. With a reduction in
loads, air-source and ground-source heat pumps make a
lot of sense to heat and cool the building.
Recently, I was cleaning out my mother's house and I
found a brochure put out by Northeast Utilities. It was
branded as their 80s and 90s program, which to me
implies that it came out in the late 1970s. It's all about
heat pumps. I could reprint this today, and it would still
be relevant. Heat pumps have certainly improved. We've
made them more efficient than what this brochure says.
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ASHRAE JOURNAL ashrae.o rg
J U LY 2023
Commercial
2020
2030
DATA SOURCE: EIA
We've made them more robust. We
certainly can install them, and they
come in all kinds of flavors, shapes and
sizes. It's not that it's a new technology,
but it's a technology that is underutilized.
We're also getting better at building
envelopes and testing them. This
helps the heat pump implementation.
The lighting industry has come leaps
and bounds in terms of moving to high
efficiency LEDs. Even if you have LEDs
that were installed 10 years ago, it's
worth even looking at those because
the efficiency has improved so much.
A key solution is efficiency, efficiency,
efficiency.
What Are Some Decarbonization Considerations Unique to
Retrofitting Compared to Newly Constructed Buildings?
The easiest market again is new construction, as it
is a blank slate. The retrofit part is a little bit harder
because you have all this legacy stuff to tackle. When
we build a new building, there's embodied carbon-
that is, carbon released because of the manufacturing
and transportation of the products and services to
making the new building. In an existing building, the
carbon for the construction has already been released-
that's water under the bridge. We don't have to worry
about it. Don't tear down everything and try to build
everything new. However, a retrofit takes some careful
thinking and planning.
But one of the good things about existing buildings
is we spend money on them every day just to maintain
them. I would ask the question of whenever you spend
money, are you doing it in a way to help reduce carbon?
And when I do whatever it is to that building to keep it
running, is that helping me on a pathway toward carbon
neutrality or taking me away from that pathway?
You might have a steam heating system and pipes keep
breaking, so you spend a lot of money to fix the pipes.
Well, maybe you could think about how to start shifting
that building to a low temperature hot water system.
Or if you're replacing variable air volume (VAV) boxes,
designing those boxes so in the future they can accommodate
a lower water temperature. If windows start failing,
am I replacing them with low-E windows? If I have
to replace the roof on a building, am I beefing up the
Annual Energy Consumption (Quads)
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ASHRAE Journal - July 2023

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