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Technical Note (National Research Council of Canada. Division of Building Research), 1959-07-01
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Hutcheon, N. B.
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DIVISION OF BUILDING RESEARCH
NATIONAL RESEARCH COUNCIL OF CANADA
'fE
C
lHI N ][ CAlL
NOTlE
No.
286NOT FOR PUBLICATION NQ,T FOR ｇｾｉＧＭＺＧｆｦ｜ＱＮＮＮＮＮＮｐＱｓｔｒｉｂｕｔｉｏｎ
PREPARED BY N.B.Hutcheon CHECKED BY
FOR INTERNAL USE
N.B.H
APPROVED BY
PREPARED FOR -The Panel on ｆｾｬｬｯｵｴ Shelters August 1959
SUBJECT Considerations of Heating ｾｮ､ Ventilation
for ｆ｡ｬｾｯｵｴ i'helters
This discussion has bE:eil preparec:. aL short notice for the guidance of the ｐ｡ｮ･ｾ on Fallout Shelters. It applies in the first instance to the improvised ｭ｡ｳｯｾｲｹＭｴｹｰ･ shelter to be constructed in an existing basement. It is ｳｵ｢ｾ･｣ｴ to correction, following further study. The tentative conclusions arising from the study ｾｲ･ as ｦｯｬｬｯｷｳｾ
1. Oxygen rleficiency and carbon dioxide build-up are unlikely to be critical; even with fresh air supply at no more than 3 cfm per person and even if liquid fuel is used for cooking and ｨ･ｾｴｩｮｧＮ
2. Considerations of odour and of clampness ｩｮ｣ＺｾＧ ; ate that a fresh air ventilation 7ate of 3 ｾｦｭ per person is inadequate and that 5 07 6 cfm would be much more
desirable.
3. Odour and humidity ｬ･ｶ･ｬｾ are likely to be veri high, even at a 5 cfm ventilat"on rate.
4. The heat and moisture given off by the occupants will be sufficient to heat and humidify the air drawn from the basement under winter ｾｯｮ､ｩｴｩｯｮｳ ｡ｾ the rate of 5 cfm per person.
5. A basement ｳｨｾｬｴ･ｲ may operate at ｡ｾｯｴｩｴ 120F above a winter basement temperature of 32 F, with no heat provided other than body ｨ･ｾｴ of the occupants. 6. One kilowatt of electric power or about 0.2 lb. of
liquid fuel per hOU1' will warm the shelters :5 n winter
to about 700F.
7. Heating is ､･ｳｩｲｾ｢ｬ･ to reduce problems of humidity ｾｮ､
8. About 100 UJ. c< ＬＧＺＬ［ｾｾｾＬＭＱ i-"':·.el C')'o,11d provide heating
and cookin; fOl' ｳＬＺＬＺＺＺｾｊｊ o'r" t·'Vo weeks,
9. Use of liquid fuel ｲｩＲｾ､ not cr8dC ＮｾｦＱｩ ｳｰ･｣ｩ＼ＳｾＮ
problems of oxygen ＬｊＬＧＺｦｬ｣ｾ･ｮｲＺＧｩ 01' caJ:bon dioxide
increase and carbor 8onoxide and fumes ｭｾｾｨｴ readily be cared {or by veLLlng.
10. Conditions under summer occt;pancy al'p lik81y to be uncomfortable due, to high temperatur:::: arK high
humidi t y, but wi11 not neeessari1y be irlto lprable.
Ventilatton for Oxygel anc Carbon
Dioxidp-ThL <iverage pe:.c::..on <'-i.. ,,'st Jlha·'. s . bout 18 cubic feet per l',)ur (cfh). The inhal/ air loses about 5% oxygen and gains 3.5 to 4% carbon dioxide. Compositions of free atmosphere alr
and of expired air on a percent by volume ｢､ｾｪｳ are as follows:
Oxygen Nitrogen Carbon dioxide Free Atmosprvns 20.9 79.1 0.03-0.04 Expired Air 15.4 79.2 4.03-4.04
If a person in a confined ＵｾＲ｣･ were ｾ inhale fresh air drawn from outside at ecr;1l breattl 'i;1d to exhale to the room,
assuming no other air change, the room condition would be that of expired air. Very roughly the ｳ｡ｾ･ ｲｯｯｾ coniition might be expected if air were supplied to the space at the rate of 18 cfh,
ｷｩｴｾ the occupant bredthing ｾ［ｲ essentially at the cespirpd condition. A ventilation ｲｾｾ･ of 0.3 cubic feet per min0te
(cfm) per person wi 11, roughly, prod\;:.;e an <'3tm'\ sphere deficient by 5% in oxygen, and increased by 4% in carbuG di6xide. This may be taken as a lower working limit for survival: ｾｯｮｳｩ､･ｲｩｮｧ
oxygen depletion and carbon di(;;dde ｢ｵｩｬ､ＭｬＬｾＮ
Minimum ventilation rate suggested for shelters is 3 cfm per person (elsewhere 5 cfm ｭ･ｮｴｩｯｾ･､ＩＮ This is 180 cfh or about ten times the inhalation rate of 18 cih per person. The atmosphere in the ｳｨｴｾｬｴ･ｲ will then bedeficient in oxygen and increased in carbon dioxide by about one tenth of the corresponding amounts for expired air, or 0.5% and 0.4%
respectively. ｾ ventilation rate of 6 :fm per person would halve these amounts. Presumably doubllng the metabolic rate over that at rest, through work or other activity, would double the amounts shown.
Atmos;,her-l'-, ＧＺＢｉＭＧｾＧ［ＱｊｲＬ｣ ｮｾＬｩＱｊＬ［ｴｩｯｬｬ wH;, ｡ｬｾＺｩ｢Ｉ､･ is about 3% rr:>r ｊＮＨＡ［ＢＧＺｾ｜ ｦ｣］ｯＧｾ ｉｮＨｾ the ',;Xi9E-i'. content of the air if) the lungs will be redllC'?. vvith <'lJU_tuc. in the ｳｾｭ･ ,Jroportion. A reduction of 0,5% in oxygen cont,::n: ,o::':'esponds -",) the
reduction in partial pTr SUEe oi ｾｸｹｧ･ｮ experienced at an altitude of about 700 ｦｌＺＺＢｾ l and must lJe ｣ｯｮｳｩ｣ｌＮｾｲ･､ ｱｵｾＮｴ･
tolerable.
The upper lim:t ｣ｯｭｭｯｮｾｹ set on tolprable carbon
dioxide in the air is about 5%. so that 2 leVi l of 0.4% must be
considered quite acceptab}.t?, at least under L'Ull',rcpncy condj..ｴｩｃＧｲｾ［Ｎ
ｖ･ｮｴｾﾷｾﾷｾｴｩｯｮ for Odour Contr.:.Q1.
It js normally ＺＰｮｳｩｾ･ｲ｡ｴｩｯｮｳ of odour which determine minimum ｶ･ｮｴＺＺＺＧｾＬｾｴ ion rat eS lInd- 1. .,;)rmaｾ 1j'I' no condit ions.
Vent::.ｾ｡ｴｩｯｮ rates of '7 to T ｾｦｭ with fresh out side air have been shown to be required to maintain odour ｾｴ a barely
perceptible level, for people of average ｬｩｶＺｾｧ habits The higher rates are required when the space per person is small
(100 cf.) and the lower rates when the ｾｰ｡｣･ per person is high
(500 cf . ) . Odours CG;!:e from the body or c Ie: hes, and t!!e amour,t
of odour produced and therefore ｴｨｾ fresh air required to ｣ｯｵｮｴ･ｲｾ
act it will 0epend on how clean people keep themselves. Smoking, as is well known, also adds to the odour problem. In a shelter with reduced space per person (80 cu.ft.), reduced ventilation rate (3 cfm per ｰ･ｲｳｯｾ［Ｌ restricted bathing and possible with additional odc\.lrs from food and wastes, the odour level will undoubtedly be very high. Under St!ｾｨ condiｴｩＰＬＬｾＬ from 30 to 50
cfm of fresh air per person '; ight weL. be requi::..'ed to keep odours to a threshold level. People who can afford it might wish to use acti vat "?d c arbon adsorbing c1evi cec' for odour contra1. The
odours proclLced by the body are not normaJly ｣ｯｾｳｩ､ｾｲ･､ to he toxic or harmful, but a high 'idour level rray produl.ｾ head;:lche in
some sensitive persons.
The metabclic rate, or the heat produced by people, rises sharply with increased activity. Much of this heat is released as latent heat contained in ･ｶｾｯｯｲ｡ｴ･､ moisture from lungs and skin, and ｷｨｩｾ･ the proportion'of sensible and latent heat may vary with cond5 ｴｬｯｲｾＬ tte followigg ｾ｡ｬｵ･ｳ may be taken
S8ated at rest Standiog at ｲ･ｳｾ
Office worker, moderately active ＿ＮＧｌｑＮｾＧ 1y"le 22") 225 22S ]59 206 265 384 431 490
The moisture gains to the air iii a ::;pace from oc:cupa!'<:s may often be important and values in oounds per ＺＧｾ UT for the
cases just given can be found 3pproxlwately by diViding the latent heat
ry
1000.The nEed to ｲ･ｭ［ｾ･ heat or moisture or both, is often a determinant CJ 1l1inimum vC't.til?ｾＧ ｾ '1 rat<::. Some idea of this may
he obtained by considering ｾｫＳ increases produced in the temperature ond humidity of an air stream introduced at the ventilation rate of 3 cfm per person, assuming heat and moist ;re are not lost in
any other way. For this purpose, the figures of 225 c:!,J 206
Btu per hour for sensible and latent ｨｑｾｴＬ respectiv?ly, are reasonable. It will ,',e found that ｴｨｾ sensitle heat ｡ｬｾｮ･ is
capable (.'f producing a rise of about 700F in the air temperatur_
This may be tolerable when the outside air brought in is very cold but lead$ to an unreasGilable figure for summer entering air conditions, indicatinq that body heat cannot be carried off by venU lation alone at ';',\e low rate of 3 cfm per person. More
ｳｰ･｣ｩｦｩ｣｡ｬｬｹｾ ｾ｡ｬ｣ｵｬ｡ｴ･､ conditions are as ｦｯｬｬｯｾｳＺ
Entering Air Leaviny Air 200m
&cl
Dry Bulb ReI. Humidity Dry I?ulb Re: .,:lumidiｴｹｾ Dew Point
730F 50% 142JF 18% 830 F
10 80 75 90 71. 5
67 75 1ｾｾ ,), 21 85
The latter two entering air conditions are for ,January and July averages for Ottawa. The, following cOf'clusions may be drawn:
1. An occupant ･ｳｳ･ｮｴｾｾｬｬｹ at rest gives off enough heat to warm completely ventilating air being introduced at the rate of 3 cfm at a ｾｩｮｴｾｲ condition.
2. An occupant essentielly at rest gives off enough m013ture to humidify highly a ｾ cfm ventil?ting stream introduced at a winter condition.
3. A ｶ･ｮｴｪＬｬ｡ｾＺ in.; c. ｾ carry ofi ｾＺ､ｹ ｬｾ
conditions.
. '.J. (;,'1111 J t '>fm DGr DeTS0ii r,2nnot . v\J;i::.:il ii' :,L',.clul.ed at·rleal.-,sddlll1eI
4. Wi th body hpat 10ｾ＼Ｚ ::0 t ..e C_'IT'JlJ.idings but mo l S:.UI'0
abso:r:eed bv the air the space wi.!..::' be iJigil in hlllddity
(7:.. 5 F rt ,,; point ... winter and 85°F dew point iL
sU,.,ner) and at times may oe sat'llraT::::d, wi:,h
condensation occurling on afty surfau:s below the dew point temper,?t'_lres shown,
It can be saie:" in :.:Jeneral ttat C0Ldi;: JJlS vvill be
very damp inside a ｳｨ･ｬｴｾｲ if unl} 3 ｣ｦｾ ｐｌｾ persun of fresh ｡ｩｾ
is ｰｾＰｩｩ､･､Ｎ The corresponding candjtians for a 5 cfm venttlation
rate are as follows:
10 67 50% 80 75 D:r::y Bulb 1120F 57 109 QＺｾｾｭｬ｡］ｨ｟ｙＮＮ 1 H .,' t 30% FOGGING 36 Qew Potnt 73.50F 57 76
At 5 cfm ventilation rate the dew point for the '''Jarm entering air conditio:'s is considerably improved. The winter condition leads to fOLjging un19ss extTd sensible ｨｾ｡ｴ is picked up in the roan., which is qUitE acceptable since ,orne heating will probably be required anyway. ｒ･ｬ｡ｴｾｶｮ ｨｵｭｩ､ｩｴｾｯｳ in summer are still high and it may be ｣｣ｾ｣ｬｵ､･､ thas 5 cfm or ｭｯｾ･ per parson may be required to kpep relative h'.Jmirlities dC'Nn j n summer. The
values ｡ｳｳｌｾ･､ take no account nf ｡､､ｾｾｩｯｮ｡ｬ ｭｯｾｳｴｵｲＸ sources or sinks or of changed moisture output of occupants d')t:: to high temperature and humictity.
The Need for Elating and Cooling
The estimation of he3cing ｾｮ､ ｣ｯｾｬｩｮｧ laaas for a basement shelter LJ'/olves some very awkward ;md difficult heat
transfer problems so that precise answers cannot be provided without:. considerable study. ｈｾｷ･ｶ･ｲｾ som2 rough e5timates may be made. Unheated structures do not follcY-j closely the outside ail'
temperature. The ｳｵｰ･ｾｳｴｲｬｬ｣ｴｵｲｾ nf a house in gttawa might well follow roughly the daily mean tel11peraulre of +10 F in January. The basement, which ｧ｡ｩｾＮ heat from the ground, which wi]' havp
ｾ･･ｮ ｫｾｰｴ warm _y the be.ｳｇｭ･Ｘｾ heat.'1r Lo the ｾ j 'i18. of ･ｾｬ･Ｎｲｧ･ｮ｣ｹＬ
lS unllkely to fall below ＳＲｾＮ Alr for ventllatlon mlght well be drawn from the basement at this ｴ･ｭｰ･ｲ｡ｴｵｲｾＮ Using these values and assuming a shelter temperature of 72°F and ar assumed
ventilation J"at0 :_f ｾＬ［［ ..'. "?T ｾｪ｣［ｲ＼ｾｯｲＮＬ the ｢｡ｳ･ｬｮ･ｾｬｴ s!-,.el,cer
,.';th 6Vi;., ｰ･ｾｳｯｮＨＢＢ. . ｾ -.1 I ',I, ."L"..L "-:l-,.•',e· Ｂｾ ... "a ﾷﾷＩｏｾＢｩｴＭＮＬＩj.'- ｾｾＮＧ ｾＮＩｰｾＮｾ w;rl+-e ...• .1. ' . ' , J . . ｨｻｾ｡ｴ \.,;; lO"cＮｾ ＷＧＮｾ 8f 300','
'-to 400C ｂｾｾ oer nour. 'he ｶ･ｮｴｾｬ｡ｴＱＰＢ load, from ｾ＿ F to
720F at 30 cfm will bc·' about 1300 Btu', er hour, an'-J. the sensible
heat ｡ＺＧｃｊｩｬｾ｢ｬ･ from the ＬｲＺ｣ｵｬ＿ＢＡｮｾｾＧ .t350 Btu ｰｾＬｻＩ IIOU1',. The body
heat wlll Just warm the ｶ･ｮｴｬｬ｡ｾｬｮＹ a:L:' to "7L :c: leaVl,nq none to maintain ｳｨ｡ｬｴＬｾ ｴ･ｭｰ･ｲＺＡｾｲ･Ｎ If no additional heat 1.3 provided the she' ｾ･ｲ is ｬｩｫ･｝ｾ to 0perate ｾＺｬｴｨ atemperlture lise of ab9ut
l20F abo'i8 hasement ｴ･ｭｲｾｲ｡ｴｵｲ･Ｌ say 44' r, w5.th basement at 32"f.
The latent heat portinn of body tleat is not a\.3ilable to
influence shelter temperatures being carried uff in the leavinc ventilation stream in the vapour, unless cond.cns ,ion reledses some of this within the ｳｨ･ｬｴ･ｾＮ
Several ｰｯｳｾｩ｢ｩｽｾｴｩ･ｳ now become apparent. As an
alternative to ｾｨ･ｬｴ･ｲ hEc;Ging; occupants might be warmly clothed, Electric heaL."g, if ava:I..Jble, . ,uld ,.is ｾＨＧｱｵｾ red to the extent of
abou'(. 1 kilowatt. Gaseous ｾｴＧ liquid fuel fol.' heating would be I'equired at the rate of ｡｢ｯｵｾ 1/6 lb. per hour, requiring abr)ut 30 cfh of air for combustion. The fuel req :i.rements f'0r heating and cooking cOlJld be supplied by 100 lb. of fuel over'c cwo-week period. Combustion of fuel within the shelter need raise no
particular problems of oxygen deficiel1c.,y or e'.en of ｣｡ｲ｢ｾＧＱ diox5 1e
build-up. The main problems would be from carbon monoxide, and perhaps irritation from fumes, and odour. Even these might be reduced or eliminated by ｶ･ｮｾｪｮｧＮ
The possibL ty of obtainin9 heat f:::om E ':luid fuel should not be ruled ｾｵｴＮ Some heat is highly desirablf in view of the condensation and dampness which is ｡ｾｭｯｳｴ certaj' to occur without it, and its provision is no'; ［Ｎｭｰｲ｡｣ｴｬ｣ｾｬＮ
The estimation of probClble ｾＧｊＮｭｭ･ｲ cond ;.tions is eve::) more diffic'.;.lt Ulan for winter. Again, m3:lY simp]j fying
assumptions must be ffiGde, but the indicati0n is ｴｨ｣ｩｾ the summer condition will be se:cious bc'..:.l with respect to tamperature and humidity or dampness, but not ｮ･｣･ｳｳｾｾｩｬｹ ｩｮｴｯｊ･ｲ｡ｾｬ･Ｎ A basement in Ottawa will seldom rise above 70 LI 75 F in sumnler, and again ti maY be assumed that air can be drawn frnm the
basement at no higher than 7SoF aven at ｭｩｾＢﾷ､Ｓｖ in July. Some advantage in improvc,j conditions wO'Jld be gai'lt:d by providing means for drawing in air from outside at night, and from the
basement during the heat of the day. Average grgund temperatures? undisturbed by any heated ｳｴｲｵ｣ｴｵｾ･Ｌ are about d8 F for Ottawa, but adjacent to a heated bas0ment may be ｡ｰｰｲ･｣ｩ｡｢ｬｾ higher. The mean ai'" temperature for July in l)ttawa is about 67 F, and the high heat storage capacity of the ｭ｡ｳｯｮｾｹ shelter ･ｮ｣ｬｯｳｵｾ｣Ｎ and adjacent earth can even ,ut daytime peak'; and car store VGry
considerable amounts of h8at if allowea to increase in temperature over the occupancy period. Considerable time and effort 'Nill be required for detailed study of the summer ｣ｯｮ､ｩｴＮｩｯｮｾ but cne
