ASHRAE Journal - June 2021 - 56

COLUMN RESIDENTIAL BUILDINGS
within a home would enable better
control.4 Current methods for
detecting occupancy-motion sensing
at the thermostat or with remote
sensors, or geofencing using phone
location-have significant limitations,
so controls must be conservative
to avoid making the home
uncomfortable if people are home
when the sensors did not detect
occupancy. More accurate occupancy
sensors could achieve more
energy savings and improve comfort.
For example, improved occupant-based
control of room-level
HVAC systems, like mini-split heat
pumps or zoned central systems,
would provide the ability to condition
only rooms where people are.
Quality Installation and Automated Fault
Detection and Diagnostics
HVAC installation faults are common
and can lead to higher energy
use and inadequate heating and
cooling.4,6,7 Better sensors and
real-time feedback to the installer
can ensure issues are identified
immediately. A few products are
available that verify quality installation.
If they were used for all HVAC
installations, the comfort improvements
and energy savings would be
significant.
A similar process can also be used
for quality installation and automated
fault detection and diagnostics,
which monitor key aspects of
the HVAC system during normal
operation to identify problems as
soon as they occur and before they
lead to system failure.4,6,8 Catching
changes in performance before the
equipment fails makes it possible to
fix the problem quickly-or to allow
more time to identify an efficient
replacement option.
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Indoor Air Quality
FIGURE 2 Smart thermostat.
Smart technology can improve
indoor air quality (IAQ) in numerous
ways. Sensors can measure a wide
range of pollutants, such as formaldehyde,
volatile organic compounds,
particulate matter, CO2 or CO. And,
it could be used to turn on a ventilation
system or to run an air handler
to make use of the air filter.4
In older homes without a dedicated
whole-house ventilation system,
sensors could automatically
turn on spot ventilation equipment,
such as a bathroom fan or a range
hood, when an increase in pollutants
is detected.9
Newer, tighter homes usually have
dedicated ventilation systems, but
the ventilation fan is usually on all
the time or operates on a schedule.
Using IAQ sensors to trigger the use
of the ventilation fan can reduce
energy consumption while still providing
enough fresh air.9,10
Outdoor air sensors and occupancy
detection should also be
included in smart ventilation
controls for energy and IAQ benefits.10,11
Outdoor air quality (OAQ)
sensors can inform ventilation
controls, shifting ventilation hours
to avoid short duration OAQ events
(such as afternoon ozone spikes) or
recirculating whole-house filtration
during long duration OAQ events
(like wildfire smoke). To improve
efficiency, occupancy detection
could be used to reduce ventilation
energy when the home is
unoccupied.
Smart Appliances
As smart home technology gains
popularity, manufacturers have
started to build communication
and control into everything. Some
J U N E 2021
FIGURE 3 Heat pump water heater with external
communication module.
appliances could see more significant
gains in efficiency or demand
response capabilities with integrated
communication and controls.
Highest priority smart appliances
are listed below, with existing gaps.
Improved Control for Water Heaters
Tank-style water heaters have
inherent thermal storage that can
be used to provide flexibility. Energy
Star and the U.S. Department of
Energy have finalized new specifications
for connected water heaters,
which communicate using open
standards and respond to remote
control signals.12
Manufacturers are adding new
sensors and controls to water heaters
focused on demand response
functionality, but the same set of
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