New-York tribune., 1917-01-10
= tho Editor OF The Tribune.

/ To tho Editor or Inc lrlDune'
Sir: with respect to the saving Of Goa
incident TO moistening the air Of dwellings
permit me to make response to the letter oi
william Kent, which denies tho possibility
Of such saving, asserting that the cost oi
evaporating tho necessary moisture oyerbal'
ances any saving due to a reduction in tenn
perature.
Mr.. Kents array Of figures would suggest
to the casual reader great scientific accuracy
but as matter OF fact they fall short OF
IT, Instead Of taking the mean average win
ter temperature and humidity Of New York
City for the months Of October to April, in
elusive which arc respectively "a degrees
Fahrenheit Of temperature and 70 per cent
OF saturation, his figures deal with the e1-
ceptional case of a zero temperature, which
only happens three or four times in some
winters and in other winters not at all, and
the freezing point, 80 degrees, which is only
occasional, even during the colder OF the
months during which artificial indoor heat
is provided.
As to these exceptional conditions, he has
assumed a minimum difference OF 10 degrees
between mostened and unmoistened air
viz, 62 degrees for the moistened air and ~
for the unmostened This difference would
be acceptable in milder weather, for the very
reason that there would be more moisture
in the air drawn from outside and heated TO
72 degrees.
In zero weather the exceeding dryness of
the inside air causes many to allow the tenn
persture to range up 10 a difference OF 20
degrees instead OF 10 degrees. This differ
ence would more than wipe out the alleged
loss of thermal units through moistening the
air which Mr. Kent alleges would take place
in zero weather
Mr.. Kent is evidently wrong in another
particular His letter deals with a room
containing 800 cubic feet. A medium sized
house, 20x50x6O feet, would have more than
thirty times this cubic content. He sug-
gests two complete changes Of air each hour
and in zero weather the need Of evaporat-
ing into this air one and three-quarters
pounds OF water every hour. In day he
would have evsporsted forty-two pounds,
which is the equivalent Of rather more than
five gallons, and for medium sized house,
az above, this would be $50 gallons-consid-
erably more than four barrels Of water.
There is no heating apparatus installed In
private houses which would accomplish this
remarkable result
have been able to keep the air sufficiently
humid in zero weather in a house Of approx
mately the size mentioned by evaporating
nine gallons Of water, the amount In ordi-
nary weather varying from two to four gal
Ions As my house is better ventilated than
the average, having very large skylght
with adjustable air openings over the cen
t-al hallway, am very certain that It is not
deficient in ventilation.
In the matter OF ventilation necessary, it
seems, at least in private house, that a
family Of perhaps six could get along on less
than $4,000 cubic feet of fresh air every
twenty-four hours, this being the aggregate
amount Of two changes of air every hour in
a house Of the size indicated. AS sometimes
figured, 1000 cubic feet an hour a person,
this amount Of fresh air would last two
weeks. am reminded that few years ago
there was an effort made to compel fac
tories to furnish q wholly unnecessary
amount OF ventilation, and the city Itself
was persuaded into wasting a million dollars
or two in a system Of school ventilation
which was a total failure
Accepting the figures OF Mr.. Kent in his
illustration Of room Of 1900 cubic feet, and
pursuing the inquiry little further along
the same line, but assuming a mean tenn