HVAC Systems: The Low-Hanging Fruit of Energy Conservation
|
Elwin McKay-Smith, Managing Director
OpSys Solutions Ltd, makers of 7NOX.
Elwin is an electrical engineer with 25 years' experience in DDC and
industrial control systems, founding member and director of the Potter
group of companies including OpSys Solutions Ltd.
|
When designing large commercial HVAC systems, energy efficiency is always top-of-mind, while energy conservation
is often an after-thought. Yet, both ideas are critical to meeting
decarbonization goals and greenhouse gas (GHG) reduction. So, what’s
the difference between the two? Well, energy efficiency involves using technology to reduce the amount of energy it takes to produce the same outcome. (e.g., chillers and boilers with a better Coefficient of Performance). Energy conservation concerns changing people’s behavior to reduce the amount of energy used (e.g., carpooling).
It’s understandable (if not predictable) that conservation often takes
a back seat. It involves changing human habits, and people dislike
change. To that point, it’s probably easier to design a more accurate
thermostat than it is to get a building full of people to stop
adjusting one. The challenges and messiness of changing human habits
often push conservation down the priority list as something to be
tackled later.
It's
unfortunate too, because even small energy conservation efforts can
have huge implications for decarbonization and GHG reduction. Human
activity, at scale, brings exponential change, but only if we can
fundamentally change our habits for the long term. It's easy to see the
potential environmental impact when you consider that buildings create around 40% of the world’s GHG emissions and that HVAC systems account for around the same percentage of a building’s total energy use.
Given
the enormous potential for energy savings, it’s imperative that the
HVAC and automation industry look for new ways to leverage research
into human psychology and current workplace trends to make buildings
more efficient. So, while it’s critical we continue to innovate
technical solutions for energy efficiency, we can maximize their impact
by applying what we know about human behavior into our designs and
processes.
Resetting Temperature Expectations
Office
temps are the proverbial bone of contention among workers. Perhaps no
topic foments the most division among workers as the “correct” office
temp. Some constantly crusade for a cooler climate, while others turn
to space heaters or thicker clothing to weather the winter months. It's
difficult or impossible to suit the thermal comfort levels of everyone
in the office. Still, most managers strive to please the majority while
keeping energy costs low.
One 2017 study
found that subjects given cognitive skills tests showed no negative
effect on “cognitive load” when temps were raised above standard
setpoints. The results suggest temperatures proscribed by leases are
likely based more on social convention
or wrong assumptions about worker productivity. Meanwhile, the
widespread over-cooling of commercial buildings is consuming more
energy, emitting more GHGs, and costing more to operate. The study’s
authors also note that maintaining an interior summer temp of 25°C
could cut office cooling energy consumption by 18%.
There’s
clearly a need to reset indoor temperature expectations to achieve real
energy conservation. But resetting expectations needs to start at the
lease level. Most health and safety departments, like in the US and
Australia, don’t mandate specific temperatures for commercial
workspaces. Instead, they offer guidelines and target ranges. So, there
are opportunities for property owners to work with tenants to shift
expectations of “acceptable” building temperatures.
Shifting
setpoint tolerances from ± 1.5 °C to ± 3°C could provide enough
flexibility and legal cover to shift indoor temps when local weather
and environmental changes allow. The change would, however, require
increased trust between owners and lessors along with an understanding
that the end goal is a greener building for everyone. Tenants would
likely expect regular energy savings reports as assurances their
efforts are contributing to decarbonization. Overall, resetting
temperature expectations for owners and occupants would place the
industry in a position to make a massive contribution to energy
conservation.
Thermal Comfort and Light Temperature
There
is a strong psychological component to our thermal comfort levels.
Feeling “hot” or “cold” isn’t only a matter of our skin receptors
communicating to our brains. In fact, research has shown that our
visual perception is also a factor in how comfortable we feel in a
heated or cooled space. Owners, technicians, and engineers should leverage this psychological component when designing integrated and automated systems.
Daylight, for example, can affect our thermal tolerance of cooler and warmer temperatures. One 2019 study published in Nature found that low levels of daylight lead to a less comfortable thermal environment during cold conditions and to a more comfortable one in warm conditions. Therefore, covering windows during summer months not only blocks solar radiation, it can also make occupants feel cooler even though internal
temps are higher. Conversely, allowing more natural sunlight into
spaces during winter months can make people feel warmer despite a lower thermostat setting.
More importantly, the study hypothesized that occupants could tolerate warmer temps within a room where illumination came from natural sunlight versus electric lighting.
The fact that sunlight makes us more resilient to temperature extremes
makes sense, given that sunlight is so essential to human physiology
and to processes like our circadian rhythm. Further, sunlight is
essential to combatting illnesses like Seasonal Affective Disorder
during winter months.
Another study examining similar effects of sunlight
on thermal comfort found that people who sat next to windows exhibited
higher thermal tolerance to ambient air temps. The study’s researchers
were able to re-adjust thermostat setpoints by 1.21 °C with a potential
energy savings of 82%. If similar setpoints became the norm, even
conservative estimates would result in significant energy savings and
GHG emissions for the industry.
To
maximize energy conservation, architects and engineers would need to
design systems to be fully automated and integrated. Window coverings
would need to be connected to systems like HVAC, lighting, occupancy,
and weather monitoring. AI and machine learning would orchestrate the
process, adjusting thermostat setpoints based upon weather forecasts,
sunlight luminance, and occupancy rate. Throughout the day, lighting
systems could slowly replace electric lights with sunlight, either by
dimming bulbs or shifting LEDs to warmer light temps. Window coverings
could shift from blackout screens to semi-opaque, helping occupants
increase their thermal tolerance.
Hybrid Work and HVAC On-Demand
With the pandemic slowing, workers are starting to trickle back into the office. However, the return to work has been a rough road for some companies like Apple, which has seen employee resistance and walkouts
by key staff members. The backlash has prompted a reversal of policy
for the mega-corp. In addition, there’s a growing trend to unionize
among workers, and businesses are feeling the pinch to give into employee demands. So, it’s safe to say some form of hybrid work is here to stay.
The
change in work schedules has also left property owners, managers, and
their tenants in a conundrum with respect to leases and utility
charges.
Some
tenants moved to a fully remote workforce, leaving behind empty office
spaces and years left on leases. To offset costs, these tenants are
attempting to renegotiate their utility charges, arguing they’re not
benefiting from heating and cooling of empty office spaces or common
building areas. Property owners are quick to point out that utility
charges must be paid because they’re a necessary OPEX item. Managers of
large properties with boilers and chillers can’t simply shut them down
or isolate service to specific areas without affecting other tenants.
The
result is building owners trying to entice tenants back to the office,
while employees are demanding to stay home. In the middle are tenants
paying for utilities they’re not using. All the while, million-dollar
HVAC systems work to heat and cool vacant spaces to the optimal 21
°C.
Moving to an HVAC on-demand
service when it makes sense is one way to solve this utility problem in
the short term. Many property owners already use cloud-based apps
to automate their after-hours HVAC programs. These platforms give
tenants the ability to schedule HVAC service after normal business
hours. They’re popular with tenants who need to extend their work
hours, and, increasingly, those with remote or hybrid staff.
On-demand
services give both the property owner and the tenant more flexibility
to lower energy costs and consumption. By extending after-hours charges
to normal business hours, landlords have a ready-made billing model—one
which could easily be adopted as an override for previous HVAC service
clauses. By billing tenants flat hourly rates, owners could justify
shutting down zones of HVAC services when those zones were unoccupied.
Further, the model would ensure tenants were only billed for utilities
they scheduled.
Research
into human psychological and physiological processes must work in
conjunction with HVAC tech innovation. Being highly predictable and
crossing cultures, nationalities, and ethnicities, these processes are
the “easy” part of the problem. The real difficulty lies in the more
unpredictable cultural and political changes like the ones we’ve
witnessed over the past few years.
Sudden
social shifts to work schedules, indoor air quality requirements, and
fast-approaching decarbonization mandates leave less time for the
industry to adjust. It’s a fact that only heightens the need to
engineer flexibility and resilience into our building designs.
For its part, the HVAC tech industry needs to speed up
innovation of affordable integrated building systems and smart
technology that allows HVAC systems to make real time adjustments based
on changes in local climates.
Building
owners will also need to ramp up investment in retrofits and new energy
saving technologies—a tough sell for those facing shrinking occupancy
rates fueled by hybrid work models.
However,
adoption of system integration, device connectivity, and cloud-based
tools will help ensure owners, managers, and their properties can
contribute to energy efficiency and conservation
efforts.
Kulve, Marije te , Luc Schlangen & Wouter van Marken Lichtenbelt. (2018). Interactions between the perception of light and temperature. Wiley Online Library. https://doi.org/10.1111/ina.12500
Zhanga, Fan, Shamila Haddad, Bahareh Nakisa, Mohammad Naim Rastgoo, Christhina Candido, Dian Tjondronegoro & Richardde Deara (2017). The effects of higher temperature setpoints during summer on office workers' cognitive load and thermal comfort. ScienceDirect, (v 123) 176-188. https://www.sciencedirect.com/science/article/abs/pii/S0360132317302834
Bio
Elwin McKay-Smith, Managing Director of OpSys Solutions Ltd, makers of 7NOX.
Elwin is an electrical engineer with 25 years' experience in DDC and
industrial control systems, founding member and director of the Potter
group of companies including OpSys Solutions Ltd.
footer
[Click Banner To Learn More]
[Home Page] [The
Automator] [About] [Subscribe
] [Contact
Us]
