ASHRAE Journal - May 2023 - 41

COLUMN IEQ APPLICATIONS
similar benefi t-cost test. Cooking comprises a small
percentage of home energy consumption, and gas cooking
also comprises a small percentage of gas consumed
by gas heating and gas water heating. So, the benefi t to
outdoor air quality in banning gas stoves would only be
a few percent of the other two gas appliances; the costs,
however, would be proportionately much higher.
When replacing a gas appliance with an electric one,
the wiring of the house must be
rated to take the maximum draw
of the appliances. California envisions
that gas water heaters and
furnaces will be replaced by heat
pumps, which are-as we know-
much more effi cient than electric
resistance appliances and so may
only require 5 kW - 10 kW of capacity.
Electric stoves, however, will
require 10 kW - 15 kW for a much
smaller impact. Increasing electric
capacity might be a minimal
cost in a new all-electric development,
but devastating in a retrofi t
situation.
Additionally, but importantly to
many, a key cost is the loss of the
utility associated with cooking with
gas. To many people who cook, switching from gas to
electric would be an enormous degradation of building
service. The costs do not come close to justifying the
benefi t to outdoor air.
Decarbonization and Climate Change
ASHRAE currently has a focus and position on decarbonization4-the
fi rst step of which is energy effi ciency
improvement. One might naively think that replacing
any gas appliance with an electric one would also
advance that, but the situation is not that simple, as
the type of appliance and its interaction with the electric
grid is very important. A case can be made that we
should not be pushing building electrifi cation at all at
the moment,5 but the decarbonization case for banning
gas stoves, in particular, is even poorer-and for the
same reasons as they are for ambient air quality: replacing
a high-peak, low-energy gas appliance with an electric
resistance one is not going to be a winner until green
electricity is too cheap to meter.
Indoor Air Quality and Health
ASHRAE Standard 62.2 has recently prohibited
unvented space heaters based on their indoor air quality
impacts. There is, after all, no doubt that nitrogen
dioxide is produced and that nitrogen dioxide is an
indoor contaminant of concern. If there were a good
justifi cation for banning gas stoves, it would make sense
it would be IAQ.
The situation, however, is a
bit more complicated than for
unvented space heaters. NO2 may
only be produced by gas cooking,
but there are a lot of contaminants
produced by any kind of cooking.
Even low-temperature cooking
will produce water vapor, which
can be problematic in some
climates; high-temperature cooking
like frying, roasting, searing,
broiling, etc., will produce a host
of contaminants including volatile
organic compounds, polyaromatic
hydrocarbons and particles. Many
of these contaminants, being
" fresh, " will be reactive and thus
can be expected to have enhanced
health risks. While only gas stoves
will produce combustion by-products, electric stoves
will produce additional contaminants as food and dust
particles interact with high temperature coils.* It is not
clear which is worse.
Regardless, then, of the fuel source, the by-products of
cooking should be vented. This, in fact, is what ASHRAE
Standard 62.2-2022 requires-that there be a range hood
that exhausts outdoors regardless of the fuel source. If
that range hood is used, the combustion by-products
should be exhausted along with the other contaminants,
and the gas stove essentially becomes a vented appliance.
The requirements in Standard 62.2 , while demonstrably
effective, are not perfect and, of course, could be
improved, e.g., with higher capture effi ciency or automatic
operation.
Some studies, often quoted in the press, show a link
between asthma and gas stoves as support for banning
*The newer induction cooktops may not suffer from this, but they
are substantially more expensive (along with the necessary cookware)
than coils and thus represent another economic barrier.
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ASHRAE Journal - May 2023

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