Inside surface temperature performance of two aluminum windows with different heating arrangements

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Inside surface temperature performance of two aluminum windows

with different heating arrangements

DIVISION OF BUILDING RESEARCH

INSIDE SURFACE TEMPERATURE PERFORMANCE OF TWO ALUMINUM WINDOWS WITH DIFFERENT

HEATING ARRANGEMENTS

by

J. R. Sasaki and W. P. Brown

ANA!.. YZED

Internal Report No. 366

of the

Division of Building Research

OTTAWA

Windows have been the subj e ct of extensive investigation by the

Division. They are critical elements in the enclosure of a building,

particularly in winter when they present cold condensing surfaces to the

interior. They become a limiting factor in the relative humidity which

can be carried, and better information is often required in order to be able

to design for improved performance in this respect. The work now

re-ported includes studies of the thermal performance of two common window

arrangements. The emphasis in this work was on the influence of the

arrangement of heating outlets under the window.

The work was carried out mainly by W. P. Brown, a mechanical engineer, while he was a research officer on the staff of the Building

Services Section. He was not able to complete the work before leaving

the Division and it is now reported by J. R. Sasaki, also a mechanical

engineer and a research officer having an interest in the technical aspects of windows.

Ottawa

December 1968

N. B. Hutcheon Associate Director

TWO ALUMINUM WINDOWS WITH DIFFERENT HEATING ARRANGEMENTS

by

J. R. Sasaki and W. P. Brown

Of all the elements comprising the building enclosure, the window normally has the lowest resistance to heat flow and the lowest

inside surface temperature s in cold weather. Because of its low

surface temperatures the window experiences condensation more

readily than the other enclosure surfaces. Low inside window surface

temperatures also contribute to discomfort which is partially de-termined by the radiant heat lost by occupants located near windows. Effort should, therefore, be made to maintain high temperatures on the inside window surfaces in cold weather in order to minimize

condensation and occupant discomfort. The thermal requirement in

the aluminum window specifications of the Canadian Government Specifications Board attempts to do just this by promoting window designs that ensure relatively high inside surface temperatures.

Inside surface temperatures of a window installed in a building are determined not only by the window design but also by the type and

location of the terminal units of the building's heating system. The

purpose of the present study is to determine the effect of heater type and configuration on the inside surface temperature performance

of two aluminum windows. One window was representative of a double

window having an adequate thermal separation between inside and outside metal members; the other window was representative of a double-glazed window having an inadequate thermal separation.

The foregoing discussion stresses the need to provide high

inside surface temperature s for satisfactory window thermal performance

in cold weather with regards to condensation and comfort. There is one

special problem, however, that may be aggravated by attempts to raise

inside window surface temperatures. This is the problem of thermal

breakage of factory-sealed double-glazing units.

The construction of sealed double -glazing units is such that the heat los s through the edge is much greater than that acros s the air space

pane will, therefore, be lower than that of the central portion. When heated air is directed against the inside surface s of the window the temperature of the central portion of the inner pane is increased more than that of the edge which is buried in a metal surround and is isolated from the heated air. If the temperature difference between the central portion and the edge becomes very large, breakage of the inner pane due to thermally-induced tensile stress may result. Window installations incorporating sealed double -glazing units, therefore, require more care in the design and location of the heating units near windows to ensure that the highest inside surface temperatures are obtained without creating a potential breakage problem.

This report describes a series of thermal tests performed on two aluminum windows with different heating arrangements on the warm side of the windows. The tests were conducted in the DBRjNRC cold-room facility with air temperatures of -lO°F and 72°F on the cold and warm sides of the windows, respectively. The inside surface tempera-tures of the windows were measured with the following heater arrangements on the warm side: a baseboard electric heater located remote from the windows providing natural-convection air flow down the inside window surface; electric heaters located beneath the windows providing natural-convection air flow up the inside window surfaces; and electric heaters located beneath the windows providing forced-convection air flow up the inside window surfaces. An additional test was conducted with the last heater arrangement using augmented heat input. Forced-convection air flow conditions were provided on the cold side of the windows in all tests.

The determination of the over-all heat transmission coefficients for the two windows is described in Appendix I.

2. DESCRIPTION OF WINDOWS

2.1 Window A

Window A was a double aluminum window consisting of two upper and two lower sashes, as shown in Figure 1. The upper prime and storm sashes were openable for cleaning purposes only; they pivoted indepen-dently about vertical side hinges and were locked to the frame by tab locks. The lower prime and storm sashes were bottom-hinged and linked to operate together; the prime sash was locked to the frame by a three -point lock. The upper and lower air space s between prime and storm sashes were separated by the muntin frame members and an

aluminum separator. The joints between frame and sash were sealed with vinyl and stainless steel weatherstripping.. The frame was

constructed in three sections separated from each other by wood thermal breaks.

The over-all frame dimensions were 39-% in. wide by 60-3/4 in. high; the upper sash, 36-% in. wide by 42-% in. high; the upper glazed area, 33 in. wide by 39 -% in. high; the lower sash, 36 -% in. wide by 15 in. high; the lower glazed area, 33 in. wide by 12-% in. high. The air space thickness for both upper and lower assemblies was 4-7/8 in.

2.2 Window B

Window B, shown in Figure 2, was an aluminum window with an upper and lower sash, each containing a factory-sealed double -glazing unit with a nominal air space thickne s s of

%

in. The upper sash pivoted about vertical side hinges and was locked to the frame by a two -point lock. The lower sash was bottom-hinged and locked to the frame by a three-point lock. The joints between frame and sash were sealed with vinyl weatherstripping. The frame and sash members were constructed in two sections which were separated by a wood thermal break.

The over-all frame dimensions were 36-% in. wide by 59-% in. high; the upper sash, 35 in. wide by 39

-1

in. high; the upper glazed area, 30 in. wide by 34-1/4 in. high; the lower sash, 35 in. wide by 17 in. high; the lower glazed area, 30 in. wide by 12 in. high.

3. DESCRIPTION OF TEST APPARATUS

The two windows were installed in the DBR/NRC cold room facility (Figure 3) described in NRC 6887. The windows were mounted in the partition with their inside face flush with the inside of the par-tition. The outside face of Window A protruded past the outer face of the partition by approximately 4 in. ; the outside face of Window B was nearly flush with the outer face of the partition. The windows were thermally isolated from the wooden partition.

The cold-room air flow conditions remained unchanged for all tests (including the heat transmission tests described in Appendix A). The cold room was maintained at test temperature with only the

main refrigeration unit operating. The main-unit fan operated at high speed and discharged refrigerated air against the partition and test windows in such a way that forced-convection air flow occurred down the cold surface of the windows. The average surface conductance on the cold face of the windows was approximately 4 Btu per (hr) (sq it) ( OF).

Temperatures were measured with 30-gauge copper-constantan thermocouples in conjunction with an electronic temperature indicator. Glass-surface temperature measurements were made with junctions fabricated by soldering i-in. lengths of copper and constantan wire

laid side by side with the leads opposed. The junction, with 2 in. of

lead wire on both sides, was taped onto the glass surface. Metal

sur-face temperatures were measured with twisted soldered junctions taped in place with 2 in. of lead wire.

Air temperatures were measured with unshielded

thermo-couples having twisted soldered junctions. On the warm side,

vertical strings of thermocouples measured air temperature

gradients 11 in. from the glas s and opposite the vertical centreline

of each window. The average of these values was taken as the

reference warm-room air temperature, two On the cold side, a

vertical string of thermocouples measured the cold-air temperature

gradient 6 in. from the plane of the windows. The mid-height

thermo-couple on this string measured the reference cold-room air temperature, t_{c '}

The locations of surface thermocouple s on windows A and B are shown in Figure 4.

The conditions on the warm side of the windows were changed for each test and are described in the following section.

4. DESCRIPTION OF TEST CONFIGURATIONS AND TEST PROCEDURE

4.1 Remote Baseboard Convector (Test 1)

The convector was located at the base of the warm room wall

opposite and 7 ft away from the test windows. The convector contained

18 electric heater elements installed end to end acros s the width of

the room. Alternate elements were wired together, forming two separate

circuits, one supplying 1250 watts and the other 1000 watts at 115 VAC. The air temperature in the warm room was controlled by

regulating the input voltage to the convector with a temperature

controller. The thermostat for the controller was located 4 ft above

the floor on the centre of the end warm-room wall. The heat input

The baseboard heating arrangement provided natural-convection

air flow down the warm face of the windows. The average surface

con-ductance value provided over the inside window surfaces was

approxi-mately 1. 5 Btu per (hr) (sq ft ) (0F).

Air and window surface temperatures were measured with the

warm room controlled to 72°F and the cold room to _10°F. These

temperatures were used for all subsequent tests.

The measured surface temperatures, t, were converted to non-dimensional temperature indices,

t - t

c

t - t

w c

1 =

-where t = measured surface temperature, OF

t_w= reference warm-air temperature, OF

t = reference cold-air temperature, of.

c

The advantage of expressing the thermal characteristics of a window in terms of temperature index rather than temperature is that, for any particular configuration, the index is practically independent

of test air temperatures over the temperature range of interest. For

the present test series, a change in the index at a given point, from te st to te st , indicate s the effect of different heating arrangements on the window thermal performance.

4.2 UnderWindow Convector

-Natural Convection (Te sts 2 to 5)

The baseboard convector was disconnected and a portable convector was placed beneath each window to simulate an

under-window heating arrangement (Figure 5). The blast heater and diffusion

box shown in the figure were not incorporated. Four heating elements

in each convector were wired together to provide 1000 watts at 115

VAC. Baffles were located in the convector outlet to give a uniform

discharge temperature.

The air temperature in the warm room was controlled by re-gulating the input voltage to the two under-window convectors; the control and heat-metering equipment described in 4. 1 were used. Each convector provided half the total heat requirement of the warm

The geometry of the convector beneath the window is shown in

Figure 6. The location of the outlet with respect to the bottom edge of

the window is described by X and Y, the outlet width is W, and the

deflector angle. 8. A sheet metal stool covered the gap between the

convector and partition.

Tests 2 to 5 were performed with two settings each of X, Y

and W, and with the deflector folded down in the open position. 4. 3 Under Window Convector

-Forced Convection (Tests 6 to 13)

The heating arrangement described in 4.2 was used for these

tests with the following modifications: removal of baffles in convector

outlet; connection of blast heater and diffuser to convector inlet. Each blast heater consisted of a blower with a capacity of 250 cfm

at 3/4 in. of water, and an external heater. The external heater

contained four heating elements wired to provide lOOO watts at 115 VAC.

The air temperature in the warm room was controlled by regulating the input voltage to the two under-window convectors and their blast heaters; control was the same as in the previous tests. The total heat input to the convectors, external heaters and blowers

was metered. Each convector assembly provided half the total

heat requirement of the warm room.

The discharge air velocity was measured at the convector outlet with a hot-wire anemometer at low velocities and a

deflecting-vane anemometer at high velocities. The geometry of the convector

is shown in Figure

6.

Four tests (7. 9, 12 and 13) were performed with two settings

each of X, Y and W, and with the deflector plate vertical. Two tests

(6 and 8) were performed with the geometry of test 7 but with different

discharge velocities. Test 10 was performed with the deflector adjusted

at 450

to direct the discharge against the window sill. Test 11 was

performed with augmented heat input; cold air was bled into the warm room to increase the heating load.

5. DISCUSSION OF TEST RESULTS

The test conditions and surface temperature indices for all te sts are listed in Table s I to IV.

5. 1 Inside -Surface Temperature

Performance - Baseboard Convector

The inside surface temperature performance s of windows A and B obtained with the remote baseboard heater configuration are

compared in Figure 7. The minimum inside surface temperature

indices for window A were: glass, 0.55; sash, 0.525; frame, 0.505.

The minimum indices for window B were: glass, 0.485; sash, 0.42;

frame, 0.305. The minimum glass temperatures measured would

have been lower for both windows had the thermocouples been located closer to the exposed edge of the inside glass; at the edge of the sealed unit in window B, the glass temperature would have been still lower.

The minimum frame and sash temperatures of Window B were lower than those of window A because the thermal separation in the frame

and sash members of window B was not as effective in reducing heat

loss as the separation and air space of window A. The minimum glass

temperature of window B was lower than that of window A because of the highly conductive heat flow path occurring around the edge of the

sealed double -glazing unit in indow B.

The low surface temperatures of window B are a reflection of the high heat transmission coefficient for this window; the over-all heat transmission coefficient of window B was 0.72 Btu per (hr) (sq ft) (OF) while that of window A was 0.56 (See Appendix 1).

5.2 Under Window Convector -Natural Convection

The vertical temperature profiles obtained for the four natural convection tests are compared with that for baseboard heating in Figure

8.

The inside surface temperatures obtained with the under-window heater arrangements were significantly higher than the temperatures

obtained with the remote baseboard heater. The bottom half of the

windows showed the largest increase in temperature.

The highest surface temperatures were obtained with the convector

outlet closest to the bottom edge of the window (tests 3 and 4). The

surface temperature s obtained with a large value of Y and a small value of X (test 2) were higher than those obtained with large X and small Y (test 5).

Because the size of the convector outlet in test 4 was twice that in test 3. the discharge air flow rate was higher and the surface temperatures in test 4 should have been higher than those in test 3. The mean discharge air temperature with the larger opening. however.

was lower than that for te st 3. This reduction in discharge

tempera-ture nullified to some extent the effect of the higher flow rate; and the surface temperatures with the larger outlet (test 4) were higher on the upper portion of the windows but lower near the sill than those of te st 3.

Test 3 gave the most uniformly high surface temperature

profile s. The se are shown in Figure 11 compared with the optimum

temperature profiles obtained with under-window heater and forced-convection air flow.

5. 3 Under - Window Convector - Forced Convection 5. 3. 1 Convector Geometry

The vertical temperature profiles obtained with five convector geometries in the forced convection tests are shown in Figure 9.

The dependence of surface temperature on convector geometry was similar to that for the natural convection tests; the highest surface temperatures were obtained with the convector outlet nearest the

bottom edge of the window (tests 9 and 10). The highest temperatures

on the lower regions of the window occurred when the discharge air

stream was deflected against the window (test 10). The temperature

profiles obtained in this test are shown in Figure 11 compared with the optimum profiles of the other test configurations.

5.3.2 Discharge Air Velocity

The vertical temperature profiles obtained with three discharge velocities are shown in Figure 10; the velocity varied from 50 to 300

ft/min. These values of discharge velocity are not unlike the normal

velocities used in building heating systems.

The window surface temperature increased with discharge

velocity because of the increase in surface conductance value. The

drop in mean discharge air temperature with increasing velocity did

not significantly affect the inside surface temperature. The

tempera-ture profiles obtained with the highest discharge velocity (test 8) are shown in Figure 11 compared with the optimum profiles of the other te st configurations.

5. 3. 3 High Heat Input

The temperature profiles obtained in test 11 with a high heat input rate are shown in Figure 11, in comparison with the optimum

profiles of the other test configurations. This test gave the highest

surface temperatures of all the tests.

Calculations have shown that the heat input rate in re sidential buildings varies between 750 and 1400 Btuj(hr) (ft of window width) whereas the input rate in commercial buildings is normally less than

400 Btuj(hr) (ft of window width). The heat input rate in test 11 was

approximately 1450 Btuj(hr) (ft of window width) which was not unlike the

higher rates used in residential buildings. The heat input rate of

approximately 450 Btu/(hr) (ft of window width) used in all the other tests was similar to that used in commercial buildings.

6. CONCLUSIONS

1. The inside surface temperatures of a window can be increased

over that obtained with remote baseboard heating by using an under -window heating arrangement and forced or natural convection air flow.

2. With under-window heater and natural-convection air flow, the

highest surface temperatures are obtained with a heater outlet of small opening located close to the bottom edge of the window.

3. With under-window heater and forced-convection air flow, the

highest surface temperatures are obtained with the heater outlet located close to the bottom edge of the window; with the convector discharge deflected towards the window; with a high discharge air velocity; and with a high rate of heat input in the convector.

4. With few exceptions, window A which has the higher inside

surface temperature s appeared to be more sensitive to change in performance with changing heater and convection conditions than window B.

5. The results of the tests on window B did not permit an accurate

estimation of the variation in thermal-breakage potential of sealed double -glazing units with changing heater and convection

conditions. The estimation of the breakage potential, or

pane, was poor because the thermocouple closest to the edge of

the sealed unit was approximately 1 in. away. Subsequent work

on sealed double -glazing units has shown that the temperature at this point behaves more like that in the central portion of the inner pane than that at the edge.

Heater Location Baseboard Under the Window

Air Flow Condition Over Window Surface Natural Natural Convection Forced Convection

Configuration of X -in.

---

23/4 6 2 3/4 6

Convector Outlet y . in .. -

--

153/41 2 14 174 T I 51.

(Figure 6) W - in. --- I 2 1 ,

9 - -«:degrees

---

180' 90' 45· 90·

Convector Discharge Velocity. V

d-It/min. --- 15 15 15 15 55 105 310 105 105 110 105 100 Air Flow Volume flow -ft3/ m i n .

---

5 5 10 10 20 35 105 35 35 40 35 65 Convector Air Temperature, t

d Maximum/Minimum - ·F --- ＱＲＵｾＰＰ

IＳＵｾ 05 120/_{9 0} 120/

9 0 88 87 81 86 88 ＱＴＰｾＰＰ 85 81 Heat Inputpe r Window Btu/hr 1260 1370 1400 1400 1350 1380 1400 1560 1440 1500 4580 1460 1400

ｾ･ｦ･ｲ･ｮ｣･ Air Temperature, ·F Warm room,_{Cold room, t}1:w 73.2 73.3 72.3 72.6 72.5 72.8 73.4 73.7 73.3 73.7 73.6 73.7 73.4

c -9.5 -9.0 -9.5 -9.3 -9.6 -9.2 -9.3 -9.2 -9.3 -8.9 -10.6 -8.8 -8.5 1 2 3 4 5 6 7 8 9 10 11 12 13

-

-',-TABLE 11 TEST CONDITIONS - WINDOW B

Test Number I 2 3 4 5 6 7 8 9 10 Z ,3

Heater Location Baseboard Under the Window

Air Flow Condition Over Window Surface Natural Natural Convection Forced Convection

Configuration of X - in.

--

3 6 3 6

Convector Outlet Y -In. -- 161/4 Z 14 I Z Z

(Figure 6) W - in._{e - .,:.}

--

I 2 1 Z

des eee e -- 180· qO· 45· QO·

Convector Discharge Velocity. Vd - it/min.

--

10 10 15 18 45 95 305 95 95 95 100 90 Air Flow Volume flow - ft3/m i n .

--

3.5 3.5 10 IZ 15 35 105 35 35 35 35 65 Convector Air Temperature. _{t d} Maximum/Minimum - -F

--

ＱＲＵｾＰＵ ｉｚｏｾｉｏ ｉｚＵｾＵ ｉｚｏｾＵ 89 86 80 84 89 ＱＳＰｾＰＰ 85 81 Heat Input per Window Btu/hr Iz60 1370 1400 1400 1350 1380 1400 1560 1440 1500 4580 1460 1400 Reference Air Temperature. ·F Warm room, tw 73.2 73.3 n.3 ra.a n.6 ra.e 73.5 73.7 73.3 73.7 73.6 73.7 73.4

Cold room. t_c -8.9 -9.0 -9.5 -9.3 -9.6 -9. Z -9.3 -9. Z -9.3 -8.9 -10.6 -8.8 -8.5 1 2 3 4 5 6 7 8 9 10 11 I Z 13

Test Number I 2 3 4 5 6 7 8 9 10 II 12 13

Heater Location&:Air Flow Condition Baseboard Under-Window Heating ｕｮ､･ｲｾｗｩｮ､ｯｷ Heating Natural Natural Convection Forced Convection

r arne - head member A I .635 .68 .695 .70 .695 .665 .675 .725 .675 .67 .755 .665 .685

l5a s h - top rail A 2 .675 .72 .725 .73 .725 .69 .705 .75 .70 .695 .78 .695 .71

blass - !in. from top sash rail A 3 .70 .74 .745 .745 .745 .72 .73 .755 .73 .73 .78 .725 .735

- ｚｾ in. from top sash rail A4 .705 .72 .73 .73 .73 .71 .725 .74 .725 .725 .765 .725 .n ｾ_ｾ - S! in. from top sash rail A 5 .685 .71 .72 .725 .72 .695 .705 .74 .705 .705 .76 .705 .71

<fJ - centre A 6 .63 .685 .695 :695 .695 .665 .67 .725 .68 .675 .745 .68 .685

"- 51 in. from bottom sash rail A7 .61 .71 .725 .74 .705 .64 .665 .745 .72 .705 .82 .715 .68

0

...

-Ｒｾ in. from bottom sash rail A8 .59 .68 .715 .715 .69 .615 .64 .735 .695 .68 .82 .71 65

-I .

from bottom sash rail A 9 .55 .62 .655 .65 .63 .575 .60 .685 .635 .64 .765 .665 .61

zIn.

Sa ah - bottom rail A 10 .56 .65 .69 .675 .65 .595 .64 .745 .685 .70 .83 .67 .635

Frame- muntin A II .505 .60 .64 .625 .595 .535 .59 .695 .635 .65 .785 .605 .56

Sash - top rail A 12 .605 .76 .80 .79 .75 .655 .74 .83 .785 .795 .94 .745 .685

.; Glass - 1"I in. {rom top sash rail A 13 .63 .745 .77 .775 .745 .685 .735 .80 .79 .78 .895 .77 .675 ｾ _{- zlin. from top sash rail A}14 .65 .745 .77 .785 .725 .69 .73 .785 .83 .79 .94 .735 .68

<fJ

E - centre A 15 .63 .76 .775 .80 .70 .675 .74 .81 .825 .83 .985 .685 .655

0 . zt_{in. from bottom sash rail A 16 .595 .785 .80 .815 .655 .66 .755 .83 .71 .875 .935 .635 .61}

11 - !in. from bottom sash rail A 17 .555 .725 .79 .765 .615 .61 .68 .805 .645 .93 .84 .59 .565

/Xl

Sa ah - bottom rail A 18 .525 .67 .735 .69 .595 .585 .645 .765 .615 .86 .795 .565 .545

Frame -sillme mbe r A 19 .505 .665 .74 .675 .58 .575 .635 .76 .595 .86 .79 .545 .525

TABLEly

TEMPERATURE INDICES ON VERTICAL CENTRE-LINE OF INSIDE WINDOW SURFACE - WINDOW B

Test Number I 2 3 4 5 6 7 8 9 10 II 12 13

Heater Location&a:Air Flow Condition Baseboard Under- Window Heating Under - Window Heating Natural Natural Convection Forced Convection

Frame .. head member B 1 .41 .42 .435 .44 .44 .42 .405 .49 .44 .425 .54 .445 .44

Sash - top rail B 2 .475 .495 .505 .515 .51 .49 .485 .58 .515 .50 .625 .515 .455

-; Glas8 - tin. from top sash rail B 3 .56 .595 .605 .615 .61 .575 .575 .65 .62 .595 .715 .615 .605

ｾ _ｾ zt_{in. from top saah rail B4 .64 .67 .68 .68 .68 .655 .655 .69 .68 .67 .75 .68 .67}

<fJ

g .. 5tin.from top sash rail B 5 .635 .67 .67 .675 .675 .65 .655 .70 .68 .67 .755 .675 .67

... - centre B 6 .635 .68 .685 .695 .69 .665 .655 .74 .695 .685 .785 .68 .685

-st

in. from bottom sash rail B7 .645 .665 .75 .76 .70 .665 .65 .795 .695 .70 .865 .72 .715

.. 2;a in. from bottom sash rail B8 .61 .62 .71 .71 .645 .625 .61 .765 .645 .645 .865 .68 .675

.. tin. from bottom sash rail B9 .485 .495 .56 .55 .50 .495 .49 .625 .515 .51 .76 .535 .53

Sash - bottom rail B 10 .42 .445 .515 .515 .44 .43 .44 .605 .475 .465 .715 .47 .465

Frame - muntin B II .31 .35 .40 .395 .29 .33 .35 .44 .375 .375 .635 .365 .36 Gta e e .. !in. from top sash rail B 12 .605 .70 .73 .735 .69 .645 .69 .775 .72 .71 .875 .67 .645 ｾ .. 21in. from top sash rail B 13 .68 .745 .74 .76 .75 .70 .745 .80 .79 .745 .87 .72 .695

ｾ _{- centre B 14 .66 .79 .805 .785 .75 .695 .755 .84 .805} .83 .95 .70 .68

<fJ

E .. 2!in. from bottom sash rail B 15 .61 .775 .825 .775 .70 .65 .70 .815 .74 .875 .98 .65 .635

0 - tin. from bottom sash rail B 16 .485 .60 .68 .65 .555 .515 .545 .645 .575 .735 .81 .52 .51

l::

0

lQSash .. bottom rail B 17 .425 .535 .61 .545 .455 .445 .50 .64 .485 .72 .68 .435 .43

STAINLESS STEEL WEATHERSTRIPPING VINYL , ｗｅａｔｈｅｒｓｔｒｉｐｐｉｎｇｾ OUTSIDE Fill INSULATION '''___I"," PlYWOOO 8" HEAD SECTION MUNTIN

-...

3-POINT LOCK

I

/

/

SILL SECTION \ INSIDE / /

""-//

HORIZONTAL SECTION THROUGH UPPER CASEMENT

FIGURE I DETAILS OF WINDOW A AND TEST MOUNTING

HORIZONTAL SECTION THROUGH UPPER CASEMENT

SEALED DOUBLE - GLAZING UNIT

( IJ \ j

-I

\

\

-r- -

---

INSIDE CAULKING

ｾ］Ｎｾ

SEPARATOR .., : HEAD SECTION MUNTIN LOWER HOPPfR SILL SECTION

/

tu..

···0!l/I

INSIDE

VINYL

WEATHERSTRIPPING

FIGURE 2 DETAILS OF WINDOW B AND TEST MOUNTING

'4.PLYWOOD _BR3724-2

MAIN REFRIGERATING

..

n

UNIT _{I I} 0

---..

WINDOWB I 0 I

_J

l_

0

•

J

•

---

Ie _I.

--;r

LOCATIONS OF PORTABLE CONVECTOR AUXILIARY WINOOWA REFRIGERATING UNIT ,0 0 I 0

,

I .J

COLD ROOM WARM ROOM

14'-4". 15'-1" 7'-4".15'-1" IASEBOARO-CONVEC1OIl

I

DOOR

I

I

DOOR

I

PLAN VIEW

M

AIR FlOW

I

..

t% MAIN WINDOWB REFRIGERATING UNIT

•

_•

Ie _I• CEILING HEIGHT· 10'-0"

•

I \ LOCATION OF

f

1

PORTABLE CONVECTOR ＸａｓｅＸＰａｒｾ LJ CONVECTOR INLET

---

₍

ｾ VERTICAL SECTION

FIGURE 3 COLD- ROOM FACILITY SHOWING LOCATION OF WINDOWS

- ) I

OA4

I

oA5 I I :::-N _ _ _ _

ｊｾＶ

'" ..,

1-oA7 I OAB bA9 i;.ｾｉａｉＳ

.

_{:::' ___} OAI4_lAI5 !::!

1-I

AI6 oAI7

WINDOW

A

LEGEND

• ALUMINUM - SURFACE TIC

oGLASS-SURFACE TIC • AIR TIC

Ｎｾｾ

ｾｉ ｾｲ

n

.

'-1"

I I

l

, .

1i:'l"" ...

ｾ

I

.

r

5

I

... I - I

I

In!

ｾ

0 . ! ! 6 _

I!II

oB7

I

oBB J Lr" • bB9

I

'.:I?

I &:::I

ｾ

I = ...--0BI2 -

Ｂｾ

ｾ

bBI3 . ''''L __

JIDL__

!::! lBI5 IBI6 --.J

,

°

L- -B17 J - +BI8-I WINDOW

8

FIGURE 4 LOCATION OF THERMOCOUPLES ON WARM SIDE OF WINDOWS

-

,-DIFFUSER (FORCED CONVECTION TESTS ONLY)

A

l--It=

E

ＭＭｩｩＭｩＳＭｩｪＭＭｅｾＭｦｽＭＭｦｽＭｦｴＭＭｆｲＭｦｪＭＭｅｽＭｴｪＭｾＭｦｲＭｩＳＭＭｴｴＭｴｪＭＭＵｾＭｅｪｾｾｩＳ

r---,

Iｾ LOCATION OF PARTITIONaWINDOW_ J:

B PLAN VIEW

8

----1

00

.:»

I I I ,

!

, 0 ,ｾＡ Iz' ｲＮｌＮＮｾＭｌＮｾ ,-.L._. __ｾ , ca , ,

,

, Z I o , - I !:: I ... I a: I ｾ l ... , o 'I Z , o I - I ... I Cl I .., I o I ...J ,, ,,

_,,

1

BAFFLES (REMOVED FOR FORCED CONVECTION TESTSI

/ \ / \ / \ /

ｾ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

I.

50·

.I

N

END VIEW (SECTION B-B) FRONT VIEW (SECTION A - A)

FIGURE 5 DETAILS OF UNDER-WINDOW CONVECTOR

PARTITION

SEPARATION

SHEET

UNDER -WINDOW

PORTABLE CONVECTOR

DEFLECTOR

e•

DEFLECTOR ANGLE

FIGURE 6

GEOMETRY OF UNDER -WI NDOW PORTABLE CONVECTOR

\

---7

GLASS HEIGHT IIN.I

A B

UPPER GLASS 39lit 34'4

LOWER GLASS 121fa 12 _{WINDOW 8 WINDOW A}

I

_ _ _ _ MID-HEIG.!tT

- - - - -

-\

I

I

,,

I

I

_t

t)

ｯＭＭＭＭＭＭＭＮｾ

0

•

SASH 0

•

MUNTIN

•

SASH ｾ

..

ｾ 1---- MID -HEIGHT

___

ｗｾｎｯｯｷｩｊＧｾｏｏｗｂ

__

/,/

ｯＭＭＭＭＭＭＭＺｾＬＧ

0

•

SASH 0

•

FRAME 0.30 0.40 0.50 I - Ie 1 = -Iw-I e 0.60 0.70 0.80

FIGURE 7

INSIDE - SURFACE TEMPERATURE INDEX PROFILES WITH

REMOTE BASEBOARD CONVECTOR

a

NATURAL CONVECTION

AIR FLOW

.---•

lC

'-,>

d

ｾ

,/

\

Ｏｾｾ

ｾＮ

, . , / '

/

0----'::::

A n

•

0-40 0·50 0·60 0-70 0'80 0·90 1·00 ｾ I'"lw-1c WINDOW

A

TEST_{(IN) (IN.) (IN.)}X Y W_I(OFl'd

•

1 BASEBOARD 0 2 2\ ＱＵｾＴ 1 110 X 3 2\ 2 1 120 o 4 ｾＴ 2 _ｉｾ 105 I A 5 6 2 ｉｾ 105 DEFLECTOR (FOLDED BACK SASH SASH MUNTI H FRAM 0·20 0·30 FRAME • ..0 xA_ SASH ---.- 0-100

---

Ｎ｟ＭＭＮＮｯ｟ｾ - - Xl' I III TEST x Y

W)I(!d

't

I'IN) liN.) (IN.)°FI

§

_...

•

I BASEBOARD WINDOW

B

2 3 ＱＶｾＴ 1 115 ..., 0 % • " , I -. -. % X 3 3 2 1 115

"''''

"'W ... % C 4 3 2 ｉｾＮ 110

ｾｾｾＮ

0. '" 0.'"

:::I"

... A 5 6 2 _1\ 110 ｾ . 0 A ｾ

__...

ｮｾＢＢＢＺＺＢＧＭＭ｟ｾ .-. nA=--'-c..;-:=--SASH __.--16 _:0-MUNTIN A .---0 ex-SASH ｾ

ﾷＭＭＭｾＷｾＬ｜

% 0 " , I -.. X ＢＧｾ ",'"_{" , x}

.'"

0 ' "

...

-:

ｾ

... _{｟ＭＭＭＭＭＭｾＮ ｾｃｄ} _ x ｾ ＮＭＭＮＭＭＭＭﾷＭＭＭＭＭｾＭｯＭ

c:::;F::::::=S

SASH __ .--- A n n FRAME A. - ＭＭＭｾＭ 0·20 0·30 0·40 0·50 0·70 0·80 0·90 1·00

FIGURE 8

INSIDE - SURFACE TEMPERATURE INDEX PROFILES WITH NATURAL

CONVECTION - EFFECT OF CONVECTOR DISCHARGE GEOMETRY

_BR3124-8

A M NT SASH SASH FRAME TEST X Y W 9 liN.) liN.! liN.! (OEG

•

I 8ASE90ARO(N.CJ 0 7 2\ '4'4 1 90 X 9 ＲｾＴ ｾ･ I 90 c 10 2\

1\

1 45 ... 12 6 ｾ･ I 90 IJ. 13 6

1\

ｉｾ･ 90 Vd • 100 FPM I d . 85 OF

.---.- '" .l .- '" .l

•

WINDOW

A

c 0·20 0·30 0040 0·50 0·60 t-Ic I ..r---'!' 'w-tc 0·70 0·80 0·90 1·00 ｆｒａｍｾ ·c._n ... SASH

-",--.-ＭＭＭＭＮＭＮｯｾ - - - . - X

ｊｊｾ

TEST X Y W,b:(

liN.) liN.! (INJ Gl

•

I BASEBOARD (N.CJ _WINDOW

B

$! 14\

...

0 7 3 I 90 '" x • "'.- 9 3 21fe I 90 "x X "''''_a:w 10 3 21/e 45 \ 0

ｾ

.... x C 1 e, Cl.'" :::>'" _{.l 12} 6 2'11 I 90

..

..J 1 ｾ Z'/e ｉｾ･

｜ｾ

'"

13 6 90 Vd .. 95 FPM Id .. 85 OF

ＭＭＭＭＭＭＮｾｾ

｟ＢＭＭｲＡｘ［Ｚ［ＧＶａＭＭＭｾ SASH _ -.-"'1l . I n ( -MUNTIN .--- -O"'.llJX-SASH N

ｾＭＭＭＭｴｱｾ

::r-; "'.-_"x ＢＧｾ _{.. s '" 0} a: ....

/'Z/

/

-.

.... x ｾｾ ..J . .

｟ＭＭＭＭｾＷ＾］ＭＭＭＭＭＭｾｑ

_:_ _ _ _0 ..J ｾ SASH _ • __e-tfJ{--- ｾＭｲｲＭ o FRAME

"'4

.·x· .- 0 0·20 0·30 0040 0'50 0·70 0·80 0·90 1·00

FIGURE 9

INSIDE -SURFACE TEMPERATURE INDEX PROFILES WITH FORCED

CONVECTION - EFFECT OF CONVECTOR DISCHARGE GEOMETRY

TESTｾｾｴ､ _{('f! . 0}// /_X I

•

I BASEBOARO IH.cJ 0 6 57 88 WINDOW

A

:-r-

_0>

x

7 107 87 :z:'"

"'"

...

_{8 308 81} "':z: 0 a:!!! ... ... % X=Ｒｾｲ

...

ｾｾ

_...

y =ＱＴｾＴＧ ｾ s W= " e =90' / . / / x ＬＯＥｾｘ _ｯｾ . ' 0 >c SASH

-_-.

0 ":::?c ...0 M NTIN .--- 0 - V- a-SASH

•

0 y ₀ ':-1"

Ｇｾｱ

{

ｾ

N

ey)',

ｾｩ

7 a:iAi

ｾ［

,.,_--.../o...x

ｾ ...0. SASH

.-

y FRAME

..

' r{ v r'\ 0·20 0·30 (}40 0·50 0·60

8t,

- t 1= _w-c 0·70 0:80 0·90 100 FRAME Ｎｯｾ 0"':"'-SASH - ＮｾＮ - 0 _

Ｍﾷｾｾｩｬｾ

TEST［ｾｉｴ､ _('f)

[1 \

•

I 8ASEBOARO_IN.CJ 0 6 47 89 _WINDOW

B

-_

... _{X 7 95 87} :z:. ｾＷ a 8 303 80 "'

...

:z: a:",

il \

ｾｷ _{X= 3'} ... :z: ｾＧＢ _{Y= 14\'} ｾ ｾ !!! _{w= "} e= 90'

ｾ ｯ

/0

. =:..---0

_..->. SASH __Ｎ｟ｾ｟ｏＺｘ .... _a MUNTIN

•

-cr'.

.,..=-SASH

O_'OrrO

-

_-Gy0

_ｾ

_ＬＧＮｾ

.

N :z:i " ,

...

c:z: '"'"

___

ＮＯＯＯｾＯ

x/

a:w ... :z: ｾｾ ｾ｣ ___...Ｍﾷｾｏｾｾ ｾ ｾ SASH

.---

--

.-

.v--" FRAME eo-4(

0

0·20 0·30 0·40 0·50 0·60 t-tc 1 = -tw-tc 0·70 0·80 0·90 1·00

FIGURE 10

INSIDE - SURFACE TEMPERATURE INDEX PROFILES WITH FORCED

CONVECTION - EFFECT OF CONVECTOR DISCHARGE VELOCITY

FRAME SASH WINDOW

A

0 ) ( ., 10 sc .... ｸＺｾｸＭ

<,

NATURAL

ｾｾ ｾｾＧＨｆＧｃＮｬ

ａｕｇｍｅｎｾ

CONVECTION HEATING (F.9/' HIGH VELOCITY /

I

ｯｾＮ _' X _ . - - - -

>0

•

/ // I /

II/!!

BASEBOARD) 0 0

ｾ

I 4S·(FC.! I

I NATURAL HIGH AUGMENTED HEATING(F.CJ

I CONVECTION VELOCITY I Ｈｾｾ

. :

0/

f

1

!

. , /

ｯｾｾ

.s-:'

....

.--y e Vd Td TEST(IN.) (DEGl FPM ('F) • I BASEBOARD (N.C.! o 3- 2 IBOO 14 122 X B 141(a90' 30B 81 o 10 ＱｾＸ 4S' 107 88 • ｉｾ

1\

90' 109 120 X =ＲｾＴＧ W= I" - NATURAL CONVECTION (Unde'- Window Heated •• TRIPLED HEAT LOAD

SASH MUNTIN SASH

-.

ｾ en ,.., :Z:II ｾｾ en", a:l;; "':z: R:en ＢＧｾ ..J ｾ 0·20 0·30 0·40 0·50 0·60 t -tc 1 = -tw-tc 0·70 0·80 0·90 1·00 FRAME ._ o.; X.!...

.-SASH - - - . __ 0 0 _ -:x_ - A _ ＭＭＭﾷＭＭｾｾｾｾｯ

.--...

Y ｾｊｦｖ､ Id f I

\

TEST I (IN.! DE FPM (OF)

_T

CD

•

I BASEBOARD(N.C.) I

\ \

I I

-

I 0 3- 2 180' 10 liS I

_B

ＮＺｾ I _WINDOW I

•

I ,.., X 8 14Stl 90-303 80 I ",II I en>- I

..

'" 0 10 ＲＱｾ 4S' 94 89 II ･ｮｾ I ",'"

•

CD

ＮｾＬ

.

",'"

_•

_{II" 21/} 8 90' 97 liS I , ｾｾ

,

"'

..

\ ..J 3'

,

ｾ X = BASEBOARDｾ 4S·(F.C.! AUGMENTED HEATINGＨｾｃｊ

W= I'

t

ｾ｣ｲｾ

•

NATURAL CONVECTION HIGH

(Under -Window Heater) \_I VELOCITY

..

TRIPLED HEAT LOAD ＬＮｾｯ

/0

•

.> /' I ____ - - __ .-:::::0 -=-2....--X_ _ _ _•

_--.-,;..-c=-

. . . - 0 - . ) ( - ...-. SASH ____-e- D- _0 -4<'

_.-MUNTIN

.-

-- o-v· )(..

.-SASH

._---,

o

0

x

t

N

ｾｸ

Ｎｾｔｅｄ

HEATING (F.C.) '" II

ｾｈｉｇｈ

VELOCITY • en>- l

..

'" ,/ ･ｮｾ " , , , , BASEBOARO __' / NATURAL

D

ＨｾｃＮＩ ｾ ",,,, ;JI:en , / CONVECTION 4S·(F.CJ °en --'et

---.'

ｾｏ］ｏＺＺＺＺＺＺＺＺＺＺＺＺＺＺ［ｾ

---'

---ｾ _-•..e----SASH

---.-

.=-0

FRAME

.---

ｯｾ 0·20 0·30 0'40 0·50 0·60 t - tc 1 = -tw-tc 0·70

o.so

0·90 1·00

FIGURE II

INSIDE - SURFACE TEMPERATURE INDEX PROFILES WITH NATURAL

AND FORCED CONVECTION - OPTIMUM CONFIGURATIONS

MEASUREMENT OF HEAT TRANSMISSION COEFFICIENTS FOR WINDOWS A AND B

The over-all heat transmission coefficients or

"U"

values for

windows A and B were measured using the guarded hot box and the

cold-room facility which are described in NRC 6887. The air flow

conditions imposed on the warm and cold sides of the test windows

are also described. The air temperatures used in the guarded

hot-box tests were approximately O°F and 72°F on the cold and warm sides, respectively.

The metered te st area of 32 sq ft consisted of window and

supporting wall. The heat flow through the supporting wall was

obtained from an auxiliary hot-box test using a specimen of known conductivity in place of the window.

Surface temperatures on the window were measured with

copper -constantan thermocouple s fabricated and attached as described

in Section 3 of this report. The surface temperatures in the auxiliary

test were measured with twisted-junction thermocouples fabricated from 30-gauge copper and constantan wires.

The values listed in Table Al for the two windows were obtained in the following manner.

(a) Heat Transmis sion Coefficient

for Supporting Wall, U sw

A rigid-insulation panel of area, A

p' thickness, x , and

conductivity, k , was located in the supportmg wall in place of the

test window. The panel area was approximately equal to that of

the test window. The conductivity of the panel material was determined

previously in a guarded hot-plate test.

U sing air temperature s approximately equal to those used in the window test, the total heat flow through the wall and panel, Qt!,

was obtained with the guarded hot box. The mean temperature

difference across the surfaces of the insulation panel, _{6tp ' and the}

mean air temperature difference, btlt were also measured.

The heat flow through the supporting wall, Q s I, of area, (32 - A p)' was the difference between the total measured heat flow,

Qt!' and the heat flow calculated for the panel, Q • Thus,

k , A • 6t

.p P

x

The heat transmission coefficient for the supporting wall, U sw?

was then;

U

_sw

=

_{(32 - A ) • 6t}

p 1

(b) Window Heat Transmission Coefficient, U

w

With the window of area, A w' installed in the supporting

wall, the total heat flow through the window and wall, Qt2' was determined

with the guarded hot box. The mean air temperature difference acros s

the specimen, M 2, and the mean temperature difference between the

window surface and air on the cold and warm sides, M_{o and} Mi' were

also measured.

The heat flow through the supporting wall, Qs2' of area, (32 - A w), was approximated by

=

(32 - A )

w Usw

The above expre s sion as sume s identical surface conductance values for the window test and the panel test; and does not account for the difference in heat flow conditions existing at the connection

between panel and supporting wall and between window and supporting

wall.

The window heat flow, Qw, was the difference between Q t 2 and

Qs2' and the over-all heat transmission coefficient, U_{w ' was calculated}

as

U

=

w

(c)

U

Window Application Factor,

--..::!!.-U

as

The over -all heat transmis sion coefficient for an idealized glas s -enclosed air space, Uas' was calculated using the air - space

conductance value given in the 1960 ASHRAE Guide and Data Book for an air-space thickness equal to that of the test window, and using

the te rnpe r atur e s and surface conductance values obtained in the

present test.

The mean surface conductance values for the warm and cold surfaces of the window, f i and fo, were calculated from the window

heat flow, Ow' the window area, A_{w ' and the mean temperature}

difference between the window surface and air on the war rn and cold

sides, _{M i and .6.to' as follows:}

f. = 1

o

w A • M. w 1 and f

=

o

c

_w A • .6.t w 0

u

w

The application factor, U is a rnea su r e of the heat

as

los s attributable to the metal sash and fr arrie rne mb e r s that, with

Test A B

A p

-

area of rigid insulation panel sq ft 14.5 14.1

X

-

mean panel thickness in. 4.07 4.06

k

-

thermal conductivity of rigid insulation Btu 0.'1.77 0.'1.77

(hr) (sqft) (OF/in.)

...

_III QJ E-t

....

_Btu QJ

a

t l total heat flow, insulation panel and wall 149.3 169.8

s::

-nl hr

o,

e _{tit mean panel-surface temperature difference} of _{65.6 64.9}

0

-...

...

p

nl

:; tIt

l

-

mean air temperature difference across specimen

of _{69.9 69.9}

.,

.s

.

"Cl

...

_bO Btu

...

_a

ｾ

-

heat flow, rigid-insulation panel

hr 64.7 6'1..4

p

a

heat flow, supporting wall Btu 84.6 107.4

sl

-

hr

U

-

heat transmission coefficient, supporting wall _{(hr) (sq ft) (OF)}Btu 0.069 0.086

sw

A

-

area of window sq ft 15.6 14.6

w

a

_{t Z}

-

heat flow, window and wall Btu 666. 804.

hr tIt

z

-

mean air temperature difference across specimen of 67.6 66.'1. tit

-

mean temperature difference, cold window surface to cold air of _{8. 10.8}

0

tIt

i

-

mean temperature difference, warm air to warrr window surface°F 23.8 '1.8.

... a

.,_{QJ s Z}

-

heat flow, supporting wall Btu_hr 77• 99.

E-t

ｾ

a

_-

heat flow, window Btu 589. 705.

-e W hr

.s

;t

U_w

-

heat transmission coefficient, window _{(hr) (sq ft) (OF)}Btu 0.56 0.73

f

i

-

inside surface conductance

Btu

1.6

(hr) (sq ft) (OF) 1.7

f

-

outside surface conductance Btu 4.7 4.5

0 (hr) (sq ft) (OF)

U

-

heat transmis sion coefficient, idealized Btu 0.54 0.55

as (hr) (sq ft) (OF)

U w

window application factor

--

_U

_-

1.04 1. 31