Another Look at Energy
Claims
In “A Close Look at Common Energy Claims”
(6/08), Martin Holladay makes the following statement about the
voluntary lowering of thermostat settings in homes with radiant
floor heating: “The only problem with the theory is
that no reputable study has ever shown it to be true, while at
least one study has disproved it.” This appears to be
based on hearsay and one rather small, unscientific survey
conducted by a Canadian utility company. A little digging into
“operative temperature” would quickly debunk
Mr. Holladay’s assertion. ASHRAE (American Society of
Heating, Refrigerating, and Air-Conditioning Engineers) has
done extensive research in this field. The fact is that as the
radiant component of comfort increases, the convective (air
temperature) component decreases. It is not just a theory, it
is well-proven.
Mr. Holladay also concludes that the lower water temperatures
required by a radiant system would result in “very
minor energy savings.” Again he shows his lack of
understanding. A hot-water baseboard system operates at around
180°F to 200°F, whereas a
radiant floor system often operates between
100°F and 130°F.
High-efficiency boilers derive their efficiencies from
extracting as much heat as possible from the flue gases. The
more heat extracted, the lower the flue gas temperature and the
more efficient the heat source. Lower supply temperatures
translate into more energy-efficient heat sources. Installing a
high-efficiency condensing boiler is a waste of time on a
conventional hot-water baseboard system, but it results in
significant energy savings on low water temperature
systems.
Lawrence Drake
Executive DirectorRadiant Panel Association
Loveland, Colo.
Author Martin Holladay responds: Mr. Drake is correct that
ASHRAE studies have shown that people near a radiant heat
source feel comfortable at lower air temperatures than people
without a nearby radiant heat source. For example, people can
feel comfortable in a cold ski chalet as long as they are
standing near a wood stove with a roaring fire. In a
well-insulated house, however, a “radiant”
floor will rarely be radiating much heat. During most daylight
hours, the temperature of the floor is likely to be close to
the indoor air temperature, except on the coldest days of the
year.
Mr. Drake is also correct that a properly sized condensing
boiler can save energy compared with a conventional boiler, as
long as the system has been carefully designed and commissioned
to assure that the boiler operates in condensing mode. It
should be pointed out, however, that condensing boilers cost
significantly more than conventional boilers and still make up
only about 15 percent of the United States market for new
boilers. The majority of new hydronic systems in the U.S.
— including in-floor radiant systems — use a
conventional boiler as a heat source.
Feeling the Financial
Squeeze
My company is building a private preschool here in Southern
California. I’ve been billing my clients on a regular
schedule and had been receiving timely payments until a few
weeks ago, when the clients learned their bank had canceled
their line of credit. That effectively shut down all work on
the project till new funding was put into place. Needless to
say, this devastated my clients, who had 40 students ready to
descend on the new school this fall.
Fortunately, my subs and suppliers have been very
understanding, which made reaching a solution with the clients
a lot easier. We all understood that the problem was with the
bank and wasn’t the clients’ fault. No one
was blamed, which helped restore the clients’
confidence in their project. They have since gathered enough
funding from private sources to continue the work, with a new
completion date set for later in the fall.
I’m sharing this as a note of warning to other
builders: If any of your clients are funding their project with
a line of credit, it would be prudent to give some thought to
backup funding, in case the bank freezes the funds.
Tony Czuleger
IMC Construction and Development
Redondo Beach, Calif.