Thermal transmittance of walls obtained by measurement on test panels in natural exposure

SfB Ab9 Build. Sci. Vol. 3, pp. 147-169. PergamonPress 1969. Printed in Great Britain

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699.86

Thermal Transmittance of Walls Obtained by Measurement on Test Panels in Natural Exposure A. W. PRAT'[* The results are given of measurements of heat flow through walls exposed to the weather in sheltered to moderate exposure and facing due north. Many of the results are published for the first time and are presented with test data already available in the literature to give a complete summary of the work carried out in Britain on heat transmission in winter through naturally-exposed walls. It is proposed to discuss the results in detail in a following paper.

INVESTIGATIONS of heat transmission through walls have been carried out over a period of many years in Britain. Experimental studies began in 1936 when a wall laboratory specially designed for this purpose was constructed at the Building Research Station. A number of considerations led to the design of the laboratory. It was decided to have a number of walls or test panels exposed to the weather for a criticism of current thermal transmittance values was that all were calculated from conductivities which had been determined in laboratory apparatus using specimens whose moisture c#ntent, if known at all, was usually different from that of actual wails. To give a uniform exposure to the walls they were arranged in a row side-by-side facing north. This could be expected to give the most severe exposure while avoiding the complication of having direct solar radiation falling on the walls during the winter test period. Because building materials are so variable while variations in building technique cause further lack of uniformity in the final assemblage, it was desirable that the walls should be as large as possible. It was decided that the test specimens should be 8 ft square, thus corresponding to singlestorey height, and each to form the outer wall of a heated room as in a normal installation. Accounts of the earlier work carried out in the laboratory, and the results obtained, have been published in a series of papers in the Journal of the Institution of 1-{eating and Ventilating Engineers. The last paper to be published[l] described thermal transmittance measurements made during the winter 1948-49. Since that time the work has continued each winter for a further period of about twelve years developing from a succession of isolated tests towards a continuing investigation of heat transfer processes in walls generally. Values of thermal

transmittance and other data obtained in this latter period and hitherto unpublished are now reported ; previous results are included for completeness. Data sheets give a sketch and description of the walls together with the main results of the experiments; these include thermal transmittance, computed thermal conductivities or conductances, periodic heat flow and other relevant data. The performance of the walls in periodic heat flow is determined by the fundamental time lag and amplitude decrement. The fundamental time lag is the delay between the temperature variation at the inner surface and a sinusoidal temperature variation of 24-h period applied at the outer surface. The amplitude decrement is the ratio of the peak values of temperature at the two surfaces. A detailed account of the measurement of periodic heat flow through certain of these wails has been given by Pratt and Lacy[2]. Most of the information on the data sheets refers to a complete heating season, or to such part as was available, and is presented as experimental results uncorrected for effects such as those caused by moisture in the materials. Where possible allowance has been made for the effects of moisture content and climate. The moisture dependance of thermal conductivity observed in these measurements has been reported elsewhere[3] and is the basis on which the adjustments have been made. The result is a series of "normalised" U values. These, it is considered, are the ultimate values that the walls would reach after they had been in position long enough for the materials to have lost their initial water of construction. It has been assumed, for example, that most of the lightweight concretes would finally have a moisture content of 5 per cent by volume. These are the values listed in Table 1 where the walls are classified according to the form of construction. It is proposed to publish a detailed examination of these, and other results, arising from the experiments in a later paper. --

*The Universityof Aston in Birmingham,Gosta Green, Birmingham4. 147

148

A.

W. P r a t t

Table 1. Brief description of test walls and "normalised" thermal transmittances, with sheltered north exposure. Wall No.

Year of test

1936-7 to 1948-9 1937 1937, 1937-8 1938-9, 1947-8

Cavity brick walls 5 1936-7 & 1937-8 6 1937, 1937-8 7 1959-60, 60-1 8 1954-5 9 1954-5 10 11 12

1954-5 1954-5 1951-2

Description

9in. 9 in. 9 in. 9 in.

"Normalised" (B.t.u./ft2hdeg.F)

Fletton Fletton, plastered Fletton, rendered Fletton, rendered, strapped and plastered

11 in. Fletton + Fletton 11 in. Fletton + Fletton ventilated cavity (iron grills) 11 in. Fletton + Fletton plastered 11 in. dense bricks, plastered (133 lb/ft 3 bricks) 11 in. dense bricks, plastered (133 lb/ft 3 bricks) cavity filled with resin-bonded glass fibre 11 in. dense bricks perforated (48 holes, 17 ~ void) plastered 11 in. Flettons, frog down + 6-hole clay blocks, plastered 11 in. Eecon 4-bole clay blocks rendered and plastered

Single-leaf walls of perforated bricks 13 1948-9 6 in. L.B.C. horizontally-perforated bricks, rendered the same, with lining of 1 in. wood wool-cement slabs on mortar 14 1956-7, 1957-8 8 in. V.2. vertically perforated bricks, plastered 15 1957-8 8 in. V.4 vertically perforated bricks, plastered 16 1958-9 & 1959-60 9 in. V.5 vertically perforated bricks, plastered 17 1959-60 9 in. V.6 vertically perforated bricks, plastered 18 1960-1 9 in. V.6/2 vertically perforated bricks, plastered 19 1957-8 & 1958-9 10 in. B.25 vertically perforated bricks, rendered and plastered 20 1958-9 9 in. H.2 horizontally perforated bricks, plastered

U-value (W/m 2 deg.C)

0.40 0.39 0.39 0"28

2"27 2"21 2"21 1 "59

0.29 0.32 0.29 0.34

1 "65

1'82 1 "65 I "93

0"15 0"29 0"23 0"23

0"85

0-37 0.24 0.26 0-26 0.26 0.30 0.37 0.21 0.35

2"10 1 "36

1"65

1'31 1"31

1 '48 1 '48 1"48 1"70

2"10 1"19 1"99

Double-leaf cavity walls, brick outer leaf 21 1948-9 11 in. Fletton brick ÷ 3 in. foamed-slag concrete blocks, plastered 22 1951-2 11 in. Fletton brick + 4¼ in. clinker concrete blocks, plastered 23 1957-60 11 in. Fletton brick + 4 in. aerated concrete (Thermalite) blocks, plastered 24 1959-61 11 in. Fletton brick ÷ 4 in. Aglite concrete blocks, plastered 25 1950-1 11 in. Fletton brick + 4 in. cored clinker concrete blocks, plastered 26 1950-1 As above but with different pattern of blocks 27 1957-8 As No. 23, but with insulated cavity and battening + plasterboard 28 1953-4 t 1 in. Fletton brick -4- 4 in. Bellrock honeycomb gypsum slabs

0.26 0.27

1 "48 1-53

0.23 0.26 0"26 0-27 0.10 0.22

1-31

Single-leaf walls of concrete cast in situ, 8 in. thick 29 1947-8 Gravel no-fines aggregate, rendered and plastered 30 1938-9 Whinstone aggregate no-fines 31 1947-8 Ham River gravel aggregate 1 : 2 : 4 32 1948-9 Ham River gravel aggregate 1 : 2 : 4 33 1948-9 Accrington brick aggregate 1 : 2 : 4 34 1947-8 Foamed-slag aggregate 1 : 2½ : 7½ rendered and plastered 35 1951-3 Foamed-slag aggregate 1 : 2½ • 7½ rendered and plastered 36 1950-1 Foamed-slag aggregate 1 : 3 : 6 rendered and plastered 37 1952-3 Foamed-slag aggregate 1 : 3 : 6 rendered and plastered 38 1952-3 Foamed-slag aggregate 1 : 2 : 8 rendered and plastered

0.42 0.41 0.59 0.63 0.47 0.21 0.21 0.23 0-23 0.19

2.39 2.33 3.35 3.58 2.67 1-19 1.19 1.31 1.31

0"26

1 "48

0"26 0"27 0"29

1 "48

0"15

0"85

Single-leaf walls of concrete blocks or slabs 39 1951-2 6 in. thick Thermalite aerated concrete blocks, rendered and plastered 40 1947-8 9 in. foamed-slag concrete cored blocks with battens and lining rendered 41 1952-3 9 in. foamed-slag concrete Besser cored blocks 42 1953-4 9 in. clinker concrete Besser cored blocks 43 1960-1 8 in. Siporex aerated concrete storey-height slabs, rendered and plastered

1.48 1 "48 1.53

0.57 1 "25

1 '08

1"53 1 "65

Thermal Transmittance o f Walls

149

Table 1 (contd.) Double-leaf walls of concrete blocks 44 45 46 47

1948-9 1952-3, 53-4, 54-5 1953-4 1958-9, 59-60

18 x 9 x 3 in. foamed-slag concrete blocks, 3in.cavity, rendered and plastered 18 x 9 x 4 in. foamed-slag concrete blocks--plastered, rendered in Aug. 1953 18 x 9 x 4 in. LECA concrete blocks; rendered and plastered 18 x 9 x 4 in. pulverised fuel-ash concrete blocks, rendered and plastered

0.25

1'42

0.20 0-23

1"13 1.31

0.22

1-25

0.43 0.37

2.44 2"10

0"22

1"25

0.27

1 '53

0-35

1 '99

0.30 0'23

1"70 1.31

0-31

1"76

0.17

0'97

0.38

2.16

0.23

1"31

0.12

0"68

0.26

1.48

0'44

2.50

0"48 0.41

2.72 2.33

0.60

3"41

0.62 0.44

3"52 2'50

0.27

1"53

0.37

2"10

0-52

2"90

0.61 0-31

3'46

0.57 0"58 0-30 0'45

3'24 3"29

Prefabr~ated walls 48

1949-50

49 50

1949-50 1949-50

51

1949-50

52

1950-1

53

1951-2

54

1949-50

55

1949-50

56

1953-4

57

1958-9

58

1957-8

59

1955-6

Wootaway: panels of aerated concrete bolted to concrete posts to form cavity, rendered outside Woolaway: the same without posts Airey: concrete slabs wired to concrete posts, plasterboard lining, with aluminium foil forming double cavity Reema: double-leaf dense concrete with integral spacer webs ½ in. fibreboard on inner face Orlit: dense concrete slabs on posts, 5½ in. cavity, 2½ in. foamed-slag concrete blocks, plastered Wilson: double-leaf blocks of dense concrete with inner lining plasterboard on integral battens The same with aluminium-faced plaster-board Weir: steel outer sheet, cavity plasterboard, cavity, aluminium faced plasterboard Hawkesley: aluminium sheet on wood frame, plasterboard inner lining, glass fibre fill Bristol: aluminium sheet on aluminium frame, hardboard inner covering, glass fibre fill Thain QSA: corrugated aluminium sheet glass fibre mat, steel inner sheet Jane Modolite: plywood with aluminium foil cavity, 2 in. glass fibre, cavity, aluminium faced plasterboard, wood frames T.D.A. : 1 in. wood panel + 1 in. sawdust cement, cavity, plasterboard on wood frames

Heavy glass walls 60 61

1937-8 1937-8

4 in. thick, hollow glass blocks Window, 3 ft 3 in. x 4 ft, in steel frames, set in 9 in. solid Fletton brick wall The same, double-glazed

Curtain walls 62

1955-6 & 1956-7

63

1955-6

64 65

1956-7 1956-7

66

1956-7

67

1955-6

68

1955-6

69 70

1956-7 1955-6

71 72 73

1938-9 1938-9 1960-1

Quicktho aluminium frame, Seco woodwool cement panel, single glazed Hills patent-glazed: steel frame and subframe, gypsum inner spandel panel, single-glazed The same: double glazed Tomo-Stramit: wood, cavity, 2 in. strawboard on wood frame. Wood frame double window Holoplast: aluminium subframe, hollow plastic spandrel panels, double-glazed LCC Picton Street: well-insulated spandrel panel on wood frame, single-glazed Herts C.C. 8 ft 3 in. school: concrete slabs and insulation for spandrel on steel frame, aluminium-framed single windows The same, with added inner glazing on wood frame B.R.S. wood aluminium subframe, woodwool cement + aluminium faced plasterboard spandrel. Single-glazed Wood-framed single-glazed window The same, double-glazed Wood-framed double-glazed window REFERENCES

1. J. J. PARSONS and G. BURNAND,Heat transmission through walls and roofs in winter and summer, J. Inst. Heat. Vent. Engrs. 18, 478 (1951). 2. A . W . PRATT and R. E. LACY, Measurement of the thermal diffusivity of some single-layer walls in buildings, lnt. J. Heat Mass Transfer, 9, 345 (1966). 3. A . W . PRATT, Some observations on the variation of the thermal conductivity of porous inorganic solids with moisture content, (Paper presented at the Thermal Conductivity Conference, N a t i o n a l Physical Laboratory, 15-17th July, 1964.)

1"76

1'70

2"55

A. I4/. Pratt

t 50

Panel No. 1 Single-leaf wall of solid brickwork, 9 in. thick, constructed in 1936 when the laboratory was built. Fletton bricks set in cement mortar. Three similar walls were built at this time and the first set of results are the mean for all three. One wall (in room 5) was retained unchanged until 1949.

I

~

Tested F e b r u a r y - M a r c h 1937 M e a n moisture c o n t e n t in April 1938 = 6-6 per cent by vol. M e a n U = 0-42 B.t.u./ft z h °F M e a n k o f brickwork = 9.0 B.t.u.in./ft 2 h ' F

Panel No. 3 Single-leaf wall of Fletton bricks, 9 in. thick, built in 1936. RenderedonoutsideearlyFebruary1937.

D e n s i t y o f bricks = 103 lb/ft 3 approx. (a) M e a s u r e m e n t s in N o v e m b e r - D e c e m b e r 1936. M e a n U = 0.45 B.t.u./ft 2 h °F M e a n k o f wall = 8.0 B.t.u.in./ft 2 h °F (b) M e a s u r e m e n t s in J a n u a r y - M a r c h 1937 M e a n U = 0.45 B.t.u./ft 2 h °F M e a n k o f wall = 8-0 B.t.u.in./ft 2 h °F (c) M e a s u r e m e n t s in 1937-8 M e a n m o i s t u r e c o n t e n t = 4-9 per cent by v o l u m e in April 1938 M e a n U = 0.44 B.t.u./ft ~ h °F M e a n k o f wall = 7.9 B.t.u.in./ft 2 h ~'F (d) M e a s u r e m e n t s in 1947-8 M e a n U = 0-40 B.t.u./ft 2 h °F M e a n k o f wall = 6"9 B.t.u.in./ft z h °F (e) M e a s u r e m e n t s in 1948-9 M e a n U = 0"40 B.t.u./ft 2 h °F M e a n k o f wall = 6.8 B.t.u.in./ft 2 h °F F u n d a m e n t a l time-Iag for 24-h period t e m p e r a t u r e wave = 5.8 h.

Panel No. 2 Single-leaf wall of solid brickwork, 9 in. thick, constructed in 1936. Fletton bricks set in cement mortar. Plastered inside in early February 1937.

(a) M e a s u r e m e n t s F e b r u a r y - M a r c h 1937 U = 0-41 B.t.u./ft z h °F k o f brickwork = 9.0 B.t.u.in./ft2 h °F (b) M e a s u r e m e n t s in 1937-8 U = 0.42 B.t.u./ft z h ~F k o f brickwork = 8.3 B.t.u.in./ft 2 h °F Moisture-content in April 1938 = 6.5 per cent by vol.

Panel No. 4 Single-leaf wall of Fletton bricks, 9 in. thick, built in 1946. Rendered on outside, strapped and plastered on laths inside. Total thickness 11 in.

Thermal Transmittance of Walls Panel No. 5 Double-leaf wall of Flettan bricks, total thickness 11 in., built in 1936. Cavity unventilated throughout.

151

Moisture content at end o f March 1938 inner leaf = 1.4 per cent by vol. outer leaf = 3.4 per cent by vol.

Panel No. 7 11-in. cavity wall of Fletton bricks. Outer leaf dark sand-faced bricks, density 109 lb/fi 3 (1.75g cm-3), inner leaf of common bricks, density 1011b/ft3(1"61gcm-3). Plastered inside. Built 25 August 1959.

(a) Measurements in N o v e m b e r - D e c e m b e r 1936 (mean o f 3 walls) U = 0.34 B.t.u./ft 2 h °F Equivalent k o f wall = 5'8 B.t.u.in./ft 2 h °F (b) Measurements in J a n u a r y - M a r c h 1937 (mean o f 2 walls) U = 0.31 B.t.u./ft 2 h °F Equivalent k o f wall = 5.3 B.t.u.in./ft 2 h °F (c) Measurements in 1937-8 U = 0'31 B.t.u./ft 2 h °F Equivalent k o f wall = 5.2 B.t.u.in./ft 2 h °F Moisture content o f outer leaf in March 1938 = 8.7 per cent by vol. Moisture content o f inner leaf in March 1938 = 1.0 per cent by vol.

Panel No. 6 Double-leaf wall of Fletton bricks, total thickness 11 in., built in 1936. Cavity ventilated as described below.

i"~

ii Tested in 1959-60 and 1960-1. B.t.u./ft 2 h °F 1959-60 1960-1 24-h mean U-value 0.30 0-29 Day time mean U-value 0.35 0.33 Night-time mean U-value 0.28 0.27 Mean thermal conductivity B.t.u.in./ft 2 h °F o f outer leaf 6.97 6.75 o f inner leaf 5.82 5.38 Moisture content, per cent by vol. in February 1960, outer leaf --- 4.5 in February 1960, inner leaf = 0-8 in March 1961, inner leaf = 1.4

Panel No. 8 Double-leaf -lel wall of dense pressed bricks, with 2½ in. cavity. Plastered ed on inside. Built in August 1954. These denser bricks were chosen 'lOS to be typical of many used in northern England. A 1 : 2 : 9 mortar mix was used to assist drying of the wall.

(a) Measurements in J a n u a r y - M a r c h 1937 Cavity ventilated with ordinary ceramic air-bricks, two at both top and bottom, each with 39 holes ~ in. square. Equivalent k o f wall = 5.8 B.t.u.in./ft 2 h °F (b) Measurements in 1937-8, natural ventilation o f cavity with iron grills in place o f ceramic air-bricks. U = 0.35 B.t.u./ft ~ h °F (c) Measurements in 1937-8, forced ventilation o f cavity with an air flow o f about 200 ft3/min. U = 0.45 B.t.u./ft 2 h °F (d) Measurements in F e b r u a r y - M a r c h 1938, ventilators blocked. U = 0-32 B.t.u./ft 2 h °F

Tested in 1954-5. Density o f bricks = 133 lb/ft -3 (2.12 g c m -3) Mean U = 0.34 B.t.u./ft 2 h °F Mean k o f outer leaf = 11"0 B.t.u.in./ft 2 h °F Mean k of inner leaf = 8-7 B.t.u.in./ft 2 h °F (without plaster) When dismantled in July 1955 the bricks were bone-dry, t here being n o loss o f weight on drying.

A.

152

Panel No. 9 Double-leaf wall o f dense pressed bricks, exactly as No. 8, but with cavity filled with shredded resin-bonded fibreglass. The fill was put in after each 18-in. lift o f brickwork was completed, to a mean density o f 2.94 lb/ft 3. Built in August 1954.

W. P r a t t Mean U = M e a n k of outer leaf = M e a n k o f inner leaf = Moisture content 25 July

0.29 B.t.u./ft 2 h °F 8.1 B.t.u.in./ft 2 h °F 5.7 B.t.u.in./ft 2 h ~F 1955 : nil.

Panel No. 11 11-in. cavity wall: outer leaf o f sand-faced Fletton bricks laid frog-down; 2½-in. cavity; inner leaf o f six-hole clay blocks 9 × 12 × 4k in. with horizontal cavities. Plastered internally. Built August 1954.

,a

Tested in 1954-5 Density o f bricks = 133 lb ft -3 (2-12 g c m -3) Density o f fill --- 2.94 lb f t - 3 (0.047 g c m - 3) M e a n U = 0.15 B.t.u./ft 2 h °F M e a n k of outer leaf = 12.6 B.t.u.in./ft 2 h °F M e a n k of inner leaf (without plaster) = 9.0 B.t.u.in/ft 2 h °F M e a n k o f cavity fill = 0.49 B.t.u.in./ft2h°F M e a n m o i s t u r e content of outer leaf, 5 April 1955, was a b o u t 4 per cent by vol. M e a n moisture contents, October 1955

Tested in 1954-5 M e a n t h e r m a l t r a n s m i t t a n c e = 0.24 B.t.u./ft 2 h °F Resistance of clay blocks = 1.49 °F ft 2 h/B.t.u. Conductivity o f Fletton bricks = 6.4 B.t.u.in./ft 2 h °F

O u t e r leaf bricks = 6-1 per cent by vol. I n n e r leaf bricks = 0.3 per cent by vol. Cavity fill = 0.2 per cent by vol.

Panel No. 10 Double-leaf wall o f dense wire-cut bricks, .from the same clay as panels 8 and 9. Each brick perforated with 48 square holes in 4 rows giving 17per cent void. Plastered inside. Built August 1954.

Panel No. 12 Double-leaf wall o f 4-hole clay blocks 9 x 9 x 4 in., each block delivered with factory-applied, 1/16 in. thick coat o f rendering on one face. After erection in July 1951, outside rendered with thin coat o f I : 1 : 6 mix, inside plastered with 1/16 in. thick undercoat o f 1 : 3 Thistle Browning and Leighton sand, followed by 1/16 in. thick Thistle plaster finish.

TMes:edun 195 ~-42B

Tested in 1954-5. Density o f bricks --- 130 lb/ft a (Effective density = 108 lb/ft-3)

t u/ft2 h F Resistance of outer leaf = 1.1 °F ft 2 h/B.t.u. Resistance o f inner leaf = 1.0 °F ft 2 h/B.t.u. F u n d a m e n t a l time-lag to 24-h t e m p e r a t u r e wave = 4.5 h A m p l i t u d e - d e c r e m e n t to 24-h temperature wave = 0.053

T h e r m a l T r a n s m i t t a n c e o f Walls Panel No. 13 Single-leaf wall of 6 in. thick x 8½ in. long x 5½ in. high horizontally perforated bricks, rendered. Built 1948.

153

Panel No. 15 Single-leaf wall of perforated clay bricks B.R.S. V.4. type. Laid with two strips of mortar in horizontal and vertical joints. Plastered inside. Bricks made from 15 per cent London Clay, 85 per cent Keuper Marl. Perforations give 44 per cent void. Built August 1957.

Tested in 1948-9. Mean thermal transmittance = 0"37 B.t.u./ft 2 h °F Mean surface-to-surface resistance = 1.81 °F ft 2 h/B.t.u. O n 7th February 1949 the wall was rendered inside, and 1-in. thick wood-wool cement slabs were bedded on the rendering, the whole being then finished with hard plaster. Testing was resumed almost immediately, with the following results: Mean thermal transmittance (March only) = 0.28 B.t.u./ft 2 h °F

Tested in 1957-8. 24-h mean U-value Day-time mean U-value Night-time mean U-value

B.t.u./ft 2 h °F 0.26 0.33 0.25

Mean surface-to-surface resistance (March & April) = 2.59 °F ft 2 h/B.t.u.

Thermal resistance o f blocks = 2.76 °F h ft2/B.t.u. (8.2 in. thick).

Panel No. 14 Single-leaf wall of perforated clay bricks, B.R.S. type 1".2, 8 x 8 x 4 in. vertical perforations giving 41 per cent void. Clay: 85 per cent Keuper Marl, 15 per cent London Clay. Laid with two strips of mortar in horizontal and vertical joints. Plastered inside.

Panel No. 16 Single-leaf wall of perforated clay bricks, B.R.S. type V.5, each brick 8¼ x 83 x 23 in., clay mix one part by volume London Clay, 6parts Keuper Marl. Vertical perforation giving 57per cent void. Laid with two strips of mortar in horizontal and vertical joints. Plastered inside. Light self-coloured bricks outside. Built 30 June 1958.

Wall built 30 October-5 November 1956.

Tested in 1958-9 and 1959-60.

Tested in 1956-7 and 1957-8. B.t.u./ft 2 h °F 1956-7

1957-8

24-h mean U-value

0-27

0.25

Day-time mean U-value

0-33

0.31

Night-time mean U-value

0.26

0.23

Thermal resistance o f blocks (1957-8) = 2.75 °F h ft2/B.t.u. (8.2 in. thick).

24-h mean U-value Day-time mean U-value Night-time mean U-value

B.t.u./ft 2 h °F 1958-9 1959-60 0.25 0-25 0.30 0.29 0"24 0.24

Moisture content in June 1960 Outer half = 2.2 per cent by vol. Inner half = 1.3 per cent by vol.

A. W. Pratt

154

Panel No. 17 Single-leaf wall of perforated clay bricks, B.R.S. type V.6. Each brick 83 x 83 x 23 in., clay mix 85 per cent Keuper Marl, 15 per cent London Clay. Vertical perforations giving 50 per cent void. Laid with two strips of mortar in horizontal and vertical joints. Plastered inside. Light self-coloured bricks outside. Built 9-12 October 1959.

Panel No. 19 Single-leaf wall of Swiss-made perforated clay bricks type B.25. Eaeh brick 30 cm wide and 13.5 cm high, perforations running full height of brick giving 37per cent void. Laid with two horizontal strips of mortar, none in vertical joints, but bituminous felt inserts in vertical slots. Rendered und plastered. Built July 1957.

Tested in 1959-60. 24-h mean U-value = 0'31 B.t.u./ft 2 h °F Day-time mean U-value = 0.35 B.t.u./ft z h °F

Tested 1957-8 and 1958-9. B.t.u./ft z h F

Night-time mean U-value = 0.29 B.t.u./ft 2 h °F

1957-8

1958-9

24-h-mean U-value

0,21

0.21

Outer half = 2.9 per cent by vol.

Day-time mean U-value

0.26

0-23

Inner half = 1.5 per cent by vol.

Night-time m e a n U-value

0.19

0.21

Moisture content in May 1960

Thermal resistance of blocks = 3.48 ~F h ftZ/B.t.u. 0 . 8 in. thick).

Panel No. 18 Single-leaf wall of vertically perforated bricks, each 8.6 x 8"6 x 2.6 in., type 11.6/2. Designed and made by Sussex & Dorking Co., of WeaM clay. 40 per cent void. Wall plastered inside. Built June 1960.

Panel No. 20 Single-leaf wall of horizontally-perforated clay bricks, B.R.S. type H.2, 13x4 in. long x 8¼ in. x 23 in. Laid with two strips of mortar in horizontal and vertical joints. Plastered inside. Built September 1958.

I Tested in 1960-1. Mean thermal transmittances, B.t.u,/ft 2 h °F 24-h

day

night

Whole season

0.35

0.38

0.33

Tested in 1958-9. 24-h mean U-value = 0.31 B.t.u./ft 2 h °F

Dec-Jan-Feb

0.34

0.37

0.33

Resistance of bricks = 1.75 °F ft 2 h/B.t.u.

T h e r m a l T r a n s m i t t a n c e o f Walls Panel No. 21 Double-leaf wall, outer leaf of Fletton bricks, 3 in. cavity, 9 x 18 x 3 in. foamed-slag concrete blocks, plastered inside. Built in 1948.

155

Panel No. 23 Double-leaf wall. Outer leaf of sand-faced Fletton bricks, inner leaf ofThermalite aerated concrete blocks, 18 x 4 x 9 in., dry density 52 lb/ft 3 (= 0"83 gm/cc). Plastered inside. Built June 1957.

I Tested in 19 7- 8,

Tested in 1948-9. M e a n U = 0.29 B.t.u./ft 2 h °F M e a n k o f f o a m e d - s l a g concrete blocks = 3"0 B.t.u.in./ft 2 h °F

Panel No. 22 Double-leaf wall, outer of Fletton bricks, inner of 9 x 18 x 4¼ in. clinker-concrete blocks plastered inside. Built in August 1951.

f

- 9 19 9-60.

B.t.u./ft 2 h °F 1957-8 1958-9 1959-60 M e a n 24-h U-value 0-25 0'24 0-23 D a y - t i m e U-value 0.31 0.30 0-27 Night-time U-value 0.23 0.23 0-22 B.t.u.in./ft 2 h °F M e a n conductivity o f brick outer leaf 7.2 7.1 6"5 M e a n conductivity o f c o n c r e t e inner leaf 2.75 2.45 2.30 Moisture contents, per cent by vol. Concrete inner leaf J a n u a r y 1958 6.3 M a r c h 1958 5.2 F e b r u a r y 1960 4.0 A u g u s t 1960 3.5 Brick outer leaf A u g u s t 1960 4-3

Panel No. 24 l l-in. cavity wall. Outer leaf of dark sand-faced Fletton bricks, density 109 lb/ft 3 (1"75 g cm- 3). Inner leaf of concrete blocks 18 x 4 x 9in., dry density 771b/ft 3 ( l . 2 3 g c m -3) with aggregate of Aglite expanded clay. Plastered inside. Built August 1959.

J";t

i,',)i

Tested 1959-60 a n d 1960-1. Tested in 1951-2. M e a n U = 0-29 B.t.u./ft 2 h °F M e a n k o f outer leaf = 7'1 B.t.u.in./ft 2 h °F M e a n k o f inner leaf = 5"2 B.t.u.in./ft 2 h °F M e a n moisture-content of inner leaf = 12 per cent by vol. D e n s i t y o f concrete blocks = 72-7 lb/ft a dried at 105°C (1.16 g c m - a ) F u n d a m e n t a l time-lag for 24-h t e m p e r a t u r e wave = 5"5 h A m p l i t u d e decrement for 24-h t e m p e r a t u r e wave = 0.050

B.t.u./ft 2 h °F 1959-60 1960-1 24-h m e a n U-value (whole season) 0.26 0.26 D a y - t i m e m e a n U-value (whole season) 0.30 0.31 Night-time m e a n U-value (whole season) 0.24 0.25 B.t.u.in./ft 2 h ° F M e a n t h e r m a l conductivity o f brick outer leaf 6.75 7.33 o f concrete i n n e r leaf 3.76 3.76 M o i s t u r e c o n t e n t per cent by vol. in F e b r u a r y 1960, concrete blocks = 8.2 in M a r c h 1961, concrete blocks = 6.4

A.

156

Panel No. 25 Double-leaf wall, outer o f Fletton bricks, inner o f 9 x 18 x 4¼ in. clinker-concrete cored blocks, with 30 per cent voids, plastered inside. Built 3 October 1950. The perforations in these blocks are closed at one end.

W. P r a t t Panel No. 27 Cavity wall. Outer leaf o f sand-faced Fletton bricks. Inner leaf o f Thermalite aerated concrete blocks 18 x 4 x 9 in., 52 lb/ft 3, with resin-bonded rockwool slabs, density 5"9 lbff? 3. nailed to cavity jace. ½ x 1½ in. wood battens nailed to room face, with inner lining o f aluminium-backed plasterboard. Wall built July 1957.

!

Tested in 19 B.t.u./ft2Lh F Tested in 1950-1. Mean U = 0.27 B.t.u./ft 2 h °F

0.10

24-h mean U-value Day-time mean U-value Night-time mean U-value

0.13 0.10 B.t.u.in./ft 2 h F

Mean k of outer leaf = 7.7 B.t.u.in./ft 2 h °F Equivalent k of inner leaf = 3"5 B.t.u.in./ft 2 h °F

Mean conductivity of brick outer leaf Mean conductivity of concrete inner leaf Mean conductivity of rockwool slabs Moisture contents, September brick = 2'1 per cent by concrete = 5'3 per cent by rockwool = 0.1 per cent by

= = =

7.2 2-4 0.29

1958, vol. vol. vol.

Panel No. 26 Double-leaf wall, outer o f Fletton bricks, inner o f 9 x 18 × 4¼ in. clinker-concrete cored blocks, three large holes giving 34 per cent void, plastered inside. Built 5 October 1950. Panel No. 28 Double-leaf wall, outer o f Fletton bricks, 2-in. cavity, inner leaf o f 2 f t x 8 f t x 4 in. cored gypsum plaster panels, built in September 1953.

d Tested in 1950-1. Density of concrete = 71 lb/ft 3 dried at 105c'C (1.14 g cm -3) Mean U = 0.28 B.t.u./ft 2 h °F Mean k of outer leaf = 7.6 B.t.u.in./ft 2 h °F Equivalent k of inner leaf = 3.8 B.t.u.in./ft 2 h °F

Tested in 1953M. Mean U = 0.23 B.t.u./ft 2 h ~F Mean k of outer leaf = 6.5 B.t.u.in/ft 2 h °F Mean resistance of inner leaf = 1-6 °F ft 2 h/B.t.u. F u n d a m e n t a l time-lag for 24-h temperature wave = 3.6 h A m p l i t u d e decrement for 24-h temperature wave = 0.049

T h e r m a l T r a n s m i t t a n c e o f Walls Panel No. 29 Single-leaf wall of gravel no-fines concrete, 1 : 0 : 10 mix, east in situ 8 in. thick, on 5 November 1946. Rendered outside and plastered inside.

157

Panel No. 31 Single-leaf wall of dense concrete. Ham River gravel aggregate, 1 : 2 : 4 mix, cast in situ 8 in. thick in November 1946.

• ,

I

Tested in 1947-8. Tested in 1947-8.

Density 143 lb/ft 3 (dried at 105°C) = 2-28 g c m -3

Density o f concrete = 115 lb/ft 3 dry (1.84 g cm -3)

U --- 0.60 B.t.u./ft 2 h °F

Mean U = 0.42 B.t.u./ft 2 h °F

k o f concrete --- 14.8 B.t.u.in./ft 2 h °F

Mean k o f concrete = 7.0 B.t.u.in./ft 2 h °F

Panel No. 30 Single-leaf wall of Whinstone no-fines concrete, 1 : 0 : 18 mix, cast in situ 8 in. thick on 24 February 1939. Rendered outside and plastered inside.

Panel No. 32 Single-leaf wall of dense concrete, Ham River gravel aggregate, 1 : 2 : 4 mix, cast in situ 8 in. thick, in September 1948 (same specification as panel 31).

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Tested in 1948-9. Density = 143 lb/ft 3 (dried at 105°C) = 2.28 g e m -3 Tested in 1939. Dry density about 110 lb/ft -~ (1-76 g c m -3) Mean U, April 1939 = 0.33 B.t.u,/ft 2 h °F

k o f concrete -- 6.0 B.t.u.in./ft 2 h °F

U = 0,63 B.t.u./ft 2 h °F k o f concrete = 16.0 B.t.u.in./ft 2 h °F Fundamental time-lag for wave = 4.9 h

24-h

period

temperature-

A.

158

Panel No. 33 Single-leaf wall o f dense concrete, Accrington brick aggregate, 1 : 2 : 4 mix, cast in situ 8 in. thick on 6 October 1948.

• .....

W. Pratt Panel No. 35 Single-leaf wall o f foamed-slag concrete, 1 : 2½ : 7½ rnix, cast in situ, 8 in. thick. Rendered outside and plastered inside. Cast on 17 July 1951.

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(C~" "C

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.

org. ,--b

Tested in 1951-2 and 1952-3, Tested in 1948-9• Density = 135 lb/ft 3 (dried at 105°C) = 2.16 g cm - s U = 0.47 B.t.u./ft 2 h °F k of concrete = 7.8 B.t.u.in./ft 2 h °F Fundamental time-lag for 24-h temperature-wave = 5.8 h

Density of concrete = 73.0 lb/ft a = 1.17 g e m -3 Measurements in 1951-2 Mean moisture-content during test Mean thermal transmittance Mean conductivity of concrete Fundamental time lag (24-h period temperature wave) Amplitude decrement of temperature wave

(dried

at

105°C)

= 16 per cent by vol. = 0.26 B.t.u./ft 2 h °F = 3'2 B.t.u.in./ft 2 h °F = 7-5 h = 0.093

Measurements in 1952-3 Mean moisture-content during test = 11 per cent by vo]. Mean thermal transmittance = 0.25 B.t.u./fl 2 h F Mean conductivity of concrete = 3"0 B.t.u.in./fl 2 h F

Panel No. 34 Single-leaf wall o f foamed-slag concrete, 1 : 2½ : 7½ mix, cast in situ, 8 in. thick• Rendered outside and plastered inside. Cast on 13 January 1947.

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Panel No. 36 Single-leaf wall o f foamed-slag concrete, 1 : 3 : 6 mix, rendered outside and plastered inside. The concrete was cast in situ, the thickness being 8 in. Made in 1950.

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~,

.

%

,.3 ~

.:..

2.

,.3 .

O~o

Tested in 1947-8. Density of concrete not measured, probably about 73 lb/ft 3 dry. Mean thermal transmittance = 0.25 B.t.u./ft 2 h °F Mean conductivity of concrete = 2-7 B.t.u.in./ft 2 h °F

.'•v"

Tested in 1950-1. Density of concrete 78 lb/ft 3 (after drying at = 1"25 g c m - 3

105°C)

Mean moisture-content during test = 19 per cent by vol. Mean thermal transmittance = 0.30 B.t.u./ft 2 h °F Mean conductivity of concrete = 3-7 B.t.u.in./ft 2 h ° F

159

T h e r m a l T r a n s m i t t a n c e o f Walls Panel No. 37 Single-leaf wall of foamed-slag concrete, 1 : 3 : 6 mix, rendered outside and plastered inside. The concrete was cast in situ, the thickness being 8 in. Made in 1952.

Tested in 1952-3. Density of concrete 771b/ft 3 (after drying at 105°C) = 1-23 g cm- 3 Mean moisture-content during test = 16 per cent by vol. Mean thermal transmittance = 0.27 B.t.u./ft 2 h °F Mean conductivity of concrete = 3.4 B.t.u.in./ft2 h °F

Panel No. 39 Single-leaf wall of aerated concrete blocks, 18 x 6 x 9 in., rendered outside and plastered inside. Built on 27 August 1951. Dry density of concrete 51"4 lb f t - 3 (0.82 g cm- 3).

Tested in 1951-2. Mean U = 0'34 B.t.u./ft2LhfF Mean k of blocks = 3.6 B.t.u.in./ft z h °F Mean moisture-content = 16 per cent by vol. Fundamental time-lag for 24-h period temperature-wave = 5"3 h Amplitude decrement for 24-h period temperature-wave = 0"165

Panel No. 38 Single-leaf wall of foamed-slag concrete, 1 : 2 : 8 mix, cast in situ, 8 in. thick; designed to give a dry density of 65 lb/ft 3. Cast in August 1952. Rendered outside and plastered inside.

Panel No. 40 Single-leaf wall of cored foamed-slag concrete blocks, 18 × 9 × 6 in., rendered outside, with plasterboard on oneinch battens inside. Built in 1946.

Tested in 19 -3.

/

Density = Mean 1.06 g

[ b y l i ~ ~ ")

Mean k of concrete = 2.8 B.t.u.in./ft 2 h °F Fundamental time-lag for 24-h period temperature-wave = 8"0 h Amplitude decrement for 24-h period temperature-wave = 0.078

1

Tested in 1947-8. Mean thermal transmittance = 0.26 B.t.u./ft 2 h °F Surface-to-surface resistance = 3"03 °F ft 2 h/B.t.u.

A. W . P r a t t

160

Panel No. 41 Single-leaf wall of18 × 9 x 9 in. foamed-slag concrete blocks, made on the Besser machine. Rendered and plastered. Built 25 September 1952.

Tested in 1952-3. D r y density 90 lb/ft 3 = 1"44 g c m - 3 M e a n t h e r m a l t r a n s m i t t a n c e = 0.30 B.t.u./ft 2 h °F M e a n moisture-content in J u n e 1953 = 7.5 per cent by vol. F u n d a m e n t a l time-lag to 24-h t e m p e r a t u r e wave = 4.8 h A m p l i t u d e decrement to 24-h t e m p e r a t u r e wave = 0-079

Panel No. 43 Single-leaf wall o f Siporex aerated concrete, in 4 storey-height slabs 2 f t wide × 8 in. thick, density 34 Ib/ft- 3 (0.54 g c m - 3). Three reinforcing bars in each slab. Plastered inside, outside finish o f silicate paint loaded with spat" chips, sprayed on, Built August 1960.

Tested in 1960-1. M e a n t h e r m a l transmittances, B.t.u./ft 2 h °F 24 h day W h o l e season 0-21 0.24 Dec-Jan-Feb 0.21 0.22

night 0.20 0.20

M e a n t h e r m a l conductivity o f concrete W h o l e season = 2.21 B.t.u.in./ft 2 h °F D e c - J a n - F e b = 2.16 B.t.u.in./ft 2 h °F M e a n moisture-content in M a r c h 1961

Panel No. 42 Single-leaf wall o f 18 x 9 x 9 in. clinker-concrete blocks, made on the Besser machine. Rendered and plastered. Dry density 71 Ib/ft 3.

= 12 per cent by vol., w h e n m e a n conductivity was 2.03 B.t.u.in./ft 2 h °F

Panel No. 44 Double-leaf wall, each of18 x 9 × 3 in.foamed-slag concrete blocks, with 3-in. air space. Rendered outside and plastered inside. Built in 1948.

Tested in 1953-4. M e a n t h e r m a l t r a n s m i t t a n c e = 0.32 B.t.u./ft 2 h °F M o i s t u r e content of inner leaf (January 1954) = 9 per cent by vol. M o i s t u r e c o n t e n t o f outer leaf (January 1954) = 18 per cent by vol, F u n d a m e n t a l time-lag to 24-h t e m p e r a t u r e wave = 2-2 h A m p l i t u d e decrement to 24-h temperature wave = 0.097

Tested in 1948-9. M e a n U = 0-28 B.t.u./ft 2 h °F M e a n k of concrete in M a r c h 1949 = 3.2 B.t.u,in,/ft 2 h °F

T h e r m a l Transmittance o f Walls

161

Panel No. 45 Double-leaf wall o f foamed-slag concrete blocks, 18 x 9 x 4¼ in., 1 : 4½ : 4½ mix, with 2½ in. cavity. Plastered inside when built in June 1952, but left unrendered in 1952-3, with drainage weep-holes at foot. Rendered outside August 1953.

Panel No. 46 Double-leaf wall of lightweight, expanded-clay aggregate concrete blocks(L.E.C.A.). 18 x 9 x 4¼ in., with2½ in. cavity. Rendered outside and plastered inside. Built August 1953.

D e n s i t y o f concrete = 83 lb/ft 3 (dried at 105°C) = 1.33 g c m - 3 M e a s u r e m e n t s in 1952-3 (wall unrendered) M e a n U = 0.23 B~t.u./ft 2 h °F M e a n k o u t e r leaf = 4.2 B.t.u.in./ft 2 h °F in N o v e m b e r 1952 M e a n k inner leaf = 3.3 B.t.u.in./ft 2 h °F in N o v e m b e r 1952

Tested in 1953-4.

F u n d a m e n t a l time-lag for 24-h period t e m p e r a t u r e wave = 7.0h

D e n s i t y o f concrete 76 lb/ft 3 dried at 105°C = 1.21 g c m 3

A m p l i t u d e d e c r e m e n t for 24-h period t e m p e r a t u r e wave = 0.030

M e a n moisture content o f o u t e r leaf in J a n u a r y 1954 = 15 per cent by vol.

M e a s u r e m e n t s in 1953--4 (wall rendered)

M e a n m o i s t u r e c o n t e n t o f m a e r leaf in J a n u a r y 1954 = 9 per cent by vol.

M e a n m o i s t u r e content, o u t e r leaf, in Jan. 1 9 5 4 = 7 per cent by vol.

M e a n U = 0.26 B.t.u./ft 2 h °F

M e a n m o i s t u r e content, inner leaf, in Jan. 1954 = 6-5 per cent by vol.

Conductivity o f inner l e a f = 4 . 7 B . t . u . i n . / f t Z h O F m / c - 8"5 per cent by vol.

M e a n U = 0.20 B.t.u./fC h °F

F u n d a m e n t a l time-lag for 24-h period t e m p e r a t u r e wave

M e a s u r e m e n t s in 1954-5 M e a n moisture content o f o u t e r leaf in April 1955 = 7.5 per cent by vol. M e a n U = 0"20 B.t.u./ft 2 h °F M e a n m o i s t u r e c o n t e n t in October 1955, o u t e r leaf 5'5 per cent by vol. M e a n moisture content in O c t o b e r 1955, inner leaf 4"6 per cent by vol.

D

with

= 4.9h A m p l i t u d e decrement for 24-h period t e m p e r a t u r e wave = 0.044

162

A,

Panel No. 47 Double-leaf wall o f concrete blocks, 18 x 4 × 9 in., with 2 in. cavity. Rendered and plastered. Blocks made o f 1 : 9 mix, cement : pulverised fuel-ash pellets. Dry density 69.5 lb/ft 3 (I'I I g c m - 3). Wall built 5 September 1958.

~

~

Tested in 1958-9 and 1959-60. 24-h mean U-value Day-time mean U-value Night-time mean U-value

B.t.u./ft 2 h °F 1958-9 1959-60 0.23 0.22 0"28 0.26 0"22 0.21

IV. P r a t t Panel No. 49 Double-leaf wall o f aerated-concrete slabs, exactly like No. 48 but without the posts. Leaves clamped together with bolts and spacing washers. Rendered outside. Built in 1949.

iaeSnMi:d~u~4~-~0"B t u / ftz h °F

Frame wall with precast concrete posts, outer cladding of" weathered dense concrete slabs, clamped to posts with copper wire ties. Inner leaf o f plasterboard nailed to wood-fillets on the posts, with a membrane o f aluminium foil giving a double cavity. Built in 1949.

Mean thermal conductivity in December-February B.t.u.in./ft z h °F 1nner leaf 3-34 3.09 Outer leaf 4.00 3.57 Moisture content, per cent by vol. Inner leaf in February 1960 = 5.1 Inner leaf in May 1960 = 5.0 Outer leaf in May 1960 = 7.1 Tested in 1949-50. Mean U = 0.22 B.t.u./ft z h °F

Panel No. 48 Double-leaf wall o f 2-in. thick, storey.height, aerated.concrete panels, bolted to cross.shaped dense.¢oncrete posts, giving 2-in. cavity. Rendered outside. Built in 1949.

Panel No. 51 Dense concrete storey-height slabs, cored to give two leaves. Half-inch thick fibreboardstuck to inner face. For the test are 8-ft square panel was cast in one piece; built in 1949.

.( q. J

Tested in 1949-50. Mean U 0-43 B.t.u./ft 2 h °F ---

Tested in 1949-50. Mean U = 0.27 B.t.u/ft 2 h °F

T h e r m a l Transmittance o f Walls Panel No. 52 Double.leaf wall with concrete posts giving a cavity width of 5½ in. Outer leaf of dense concrete slabs 2 f t high by 4 f t wide, 1½ in. thick except at edges where they thicken to 2 in. Inner ieaf o f foamed-slag concrete blocks 18 x 2½ × 9 in, plastered inside (Orlit wall).

163

(b) Measurements in February-March 1952 (foil-backed plasterboard) Mean U = 0.23 B.t.u,/ft 2 h °F Fundamental time-lag for 24-h period temperature wave = 4.1 h Amplitude-decrement for 24-h period temperature wave = 0.030 Note: The outer face of these blocks was made with exposed aggregate, giving a rough surface to simulate natural stone.

Panel No. 54 Three-leaf wall, with two 1-in. cavities. Outer leaf of steel sheet with vertical stiffeners, other leaves of plasterboard separated by wood strips, the second one being aluminium-foil backed. Built in 1949.

Tested in 1950-1. Mean thermal transmittance = 0"35 B.t.u./ft 2 h °F

Panel No. 53 Wall of double-leaf dense concrete blocks 18 x 8 x 9 in., the leaves of each block being joined by three 1-in. square concrete ties. Along the top of each inner leaf runs a 1-in. square fillet o f nailable concrete, to which is nailed a plasterboard inner lining. Wall built in July 1951. On 28 January 1952 the plain plasterboard lining was replaced by one with aluminium foil facing the cavity.

Tested in 1949-50. Mean U = 0.31 B.t.u./ft 2 h °F

Panel No. 55 Prefabricated wall, with wood frames, corrugated aluminium outer skin, hardboard inner skin, insulated with 3-in. glass fibre quilt.

!, (a) Measurements in October 1951-January 1952 (plain plasterboard)

R~ r ~. d

Mean U = 0.30 B.t.u./ft z h °F Fundamental time-lag for 24-h period temperature wave = 3.9 h Amplitude-decrement for 24-h period temperature wave = 0.048

Tested in 1949-50 and 1950-1. Mean U = 0.17 B.t.u.fft2 h ° F Surface-to-surface resist~mce -- 5.2 °F ft a h]B.t.u.

164

A. W. Pratt

Panel No. 56 Prefabricated wall with aluminium framing and outer skin of aluminium with metal stiffeners. The inner skin is of hardboard with aluminium stiffeners, connected to the main frames by wood strips, The panels are insulated with a glass fibre quilt, 1"5 in. thick. The test wall consisted of two 4-ft wide sections with framing between as shown in the sketch.

Panel No. 58 Wood-framed wall, with light-weight infill panels. Plywood outer face, lined with aluminium fail, glassfibre quilts 2 in. thick with cavity either side, inner face o f aluminium-backed plasterboard. Built in 1957.

~

, f Aluminium - booked ptosferDoard

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~

Two inch-fhick qlO=fil~e

t! Ry~

Tested in 1957-8. 24-h m e a n U-value D a y t i m e m e a n U-value Night-time m e a n U-value

B.t.u./ft 2 h °F 0.12 0.12 0.11

Tested in 1953--4. M e a n t h e r m a l t r a n s m i t t a n c e = 0"35 B.t.u./ft 2 h °F

Panel No. 57 Metal wall designed for factories, not load-bearing, lnner leaf of steel trays 2ftwide, corrugated aluminium outer leaf screwed to horizontal stiffeners on steel trays, with I in. resin-bonded fibreglass quilt clamped between the two leaves. Built in 1958.

Panel No. 59 Framed wall of 3 x 2 in. softwood, clad on outside with 40 in. square panels of I in. thick wood, backed with 1 in. thickness of sawdust-cement. Lined internally with plasterboard. Built in August 1955.

4Gx 40"Timber froys af 3"x I" Thinnings wood

Tape

ii

"Corru a+e a,um,°,om

Sawdusf-cement infiIl to' "troy

~ , ~ - - - - Alurniniurn footing Tested in 1958-9. M e a n U = 0.22 B.t.u./ft 2 h °F

Tested in 1955-6. M e a n U = 0.26 B.t.u./ft 2 h ':F

/.Plosh~tboord .~ ¢3 "x2"Woodframe

T h e r m a l Transmittance o f Walls Panel No. 60 Single-leaf wall of hollow glass blocks 5¼ in. square and 4 in. thick, set in 1 : 2 : 9 mortar with joints approximately ¼ in. thick. Expanded metal reinforcement in strips 2½ in. wide was included in every third horizontal joint. The blocks were laid with the outside ienticular pattern vertical.

Tested in 1937-8. Mean thermal transmittance = 0"44 B.t.u./ft 2 h °F

165

Thermal transmittances, B.t.u./ft z h °F

Window single-glazed

Window double-glazed

October 1937 November 1937 December 1937 January 1938

0.44 0.49 0.51 0"49

0.37 0.42 0.43 0'44

Whole period

0.48

0.41

Panel No. 62 School wall, with aluminium sub-frame at 3 f t 4 in. centres, bolted to steel main-frame. Single-glazing and lower panels fixed with U-section aluminium glazing beads on stainless-steel spring clips. Built in 1955.

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Panel No. 61 Single-leaf wail, 9-in. solid Fletton bricks, plastered inside, with steel-framed window 4 ft high x 3 f t 3 in. wide, set in wood outer frame, sill 3 f t 4 in. above floor. In alternate weeks the window was doable-glazed with removable inner lights, giving a cavity 2¼ in. wide. Built 1937.

-. ~

/ S ' l ' e e l main-frame Aluminium sub-frame

11~

~

II

~

L>~

~ holding windows and low

panels

L~wood- wool stabs

s,ote cil

doin'l's sealed wifh mastic ~ (no glazing - bead along "l'his joint)

[

(asbestos-cemen't" faced]

Tested in 1955-6 and 1956-7. Mean thermal transmittances of 8-ft square panel, B.t.u./ft 2 h °F 1955-6 1956-7 1956-7 Oct.-Mar. Nov.-Feb. 24-h (09-09 G M T ) Day-time (09-1630 G M T ) Night-time (16304)9 G M T )

0-60

0.54 0.29 0.61

0.59

Estimated U of wood-wool slab panels = 0.36 B.t.u./ft 2 h °F

Distribution of heat-flow

Part of wall

Glass (single-glazed) Metal framing Wood-wool slab panels Tested 193%8.

Area as Proportion of proportion of total heatwhole panel flow (%) 0.59 0.09 0.32

71 13 16

A. HI. P r a t t

166

Panel No. 63 Glass-clad wall on T-section steel sub-frame, with bracket fixings to steel main frame (box-section posts and lattice horizontal members). Single-glazed windows. Separate gypsumplaster inner leaf below window-till, resting on structural floor. Built in 1955,

Mean U, B.t.u./ft 2 h F 24-h (09-09 GMT) 0.44 Day-time (09-1630 GMT) 0-24 Night-time (1630-09 GMT) 0.50 Estimated mean U of lower panels = 0.21 B.t.u./ft 2 h ' F Estimated mean U of window = 0.77 13.t.u./ft 2 h ' F

S+eel Distribution of heat-flow

Steel T - s e c f i o n _ ~ . = ~ s - - - ' P ~ ~ Connections with Part of wall

Area as Proportion of proportion of total heatwhole wall flow (%)

holding glozir~ Geergion- wired

~

II ~J~| Gypsumplaster ~ " ~ " - - ~ " y honeycombedpanel inner leaf Asbestos-cement in+ermediote panel-

Glass, double with airspace about 3/16 in. Window framing Upper spandrel panel Lower spandrel panel

0.51 0.05 0.13 0.32

71 8 9 12

Tested in 1955-6. Mean U = 0.62 B.t.u./ft 2 h °F Estimated U of panel below window c i l l = 0-28 B.t.u./ft 2 h °F Distribution of heat-flow Area as Proportion of proportion of total heatwhole panel flow (%)

Part of wall

Glass, including metal sub-frames exposed to room air Panel below window

0.66 0-34

86 14

Panel No. 64 This is panel No. 63 modified in August 1956 by the substitution of new glazing units for the old ones. The new windows were sealed double-glazed ones with a cavity about 3/16 in. wide. The other glass-faced panels consisted essentially of a dished steel tray, painted inside, with a roughcast glass face. They were held in place by the "patent-glazing" technique previously used. The steel perimeter-beam was boxed in.

Panel No. 65 Wood-framed wall, with outer leaf of ¼ in. wood boards, ~ in. air-space and inner leaf of 2 in. thick compressed-strawboard. Centre-hung, wood-framed double windows. Built in 1956.

~

Wood frame

"h'e-hung double-window in Strawboard panel in wood boordircj

Tested in 1956-7.

Gloss-faced ponels~ Steel sub-&ame with oluminium copping holding glozing

~

o

o

B.t.u./ft 2 h ~F

Mean U of panel (24-h) Mean U o f panel (day-time 0915-1630 G M T ) Mean U o f p a n e l (night-time 1630-0915 GMT) Estimated U of spandrel panel alone Estimated U of double-glazing (without framing)

d

0.27 0.13 0-31 0' 17 0.50

Distribution of heat-flow

Gloss -face panels "---

I1 .@;able-

..

~ . ] ~ ~

glazing

I L~r- ~ ~ honeycombed II panel inner leaf

Tested in 1956-7.

Part of wall

Glass Wood framing Strawboard panels

Area as Proportion of proportion of total heatwhole panel flow (%) 0.45 0.25 0'31

65 18 17

Thermal Transmittance of Walls Panel No. 66 Wall with aluminium subframe which is fixed to each section of the panel. Each mullion is in two channel-shaped parts fixed to their respective panel-section, with a sliding junction to allow for movements. Spandrel panels of cored plastic construction 1~ in. thick, the vertical channels being filled with glass-fibre insulation. Double-glazed windows, with sealed units (½ in. airspace).

167

Mean U = 0.52 B.t.u./ft 2 h °F Estimated U of spandrel panels = 0.13 B.t.u./ft 2 h °F Distribution of heat-flow

Part of wall

Area as Proportion of proportion of total heatwhole wall flow (%)

Aluminium l

mul lions

Hal low panels of resin bonded;

Glass, single Wood window frame Spandrel panel

0-55 0.13 0.33

86 6 8

paoer wi~'h

gloss-fibre

fil ling

"i

,-..Herme~'ical ly sealed

double-glozing

"" wood ci I I -'~

Tested in 1956-7. Mean thermal transmittances, B.t.u./ft z h °F 24-h (09--09 GMT) 0-37 Day-time (09-1630 GMT) 0.18 Night-time (1630-09 GMT) 0.43 Estimated overall U of plastic panel = 0"24 B.t.u./ft 2 h °F

Panel No. 68 Hefts County Council 8 f t 3 in. grid wall. Mainframe of 5 in. square steel lattice columns and steel lattice horizontal members. Columns covered with precast plaster casing. Outer cladding of dense concrete slabs, lnner leaf of wood-wool slabs covered with plasterboard. Single-glazed window with aluminium frame.

Distribution of heat-flow

Part of wall

Area as Proportion of proportion of total heatwhole panel flow (,%o)

Glass (double-glazed) Metal framing Plastic panels

0.55 0.15 0.29

56 30 14

Aluminium window frame-.,,

Dense- concre-l-e ~ ponelsbolted ~t -to steel -column

Steel column with pl o s'l'er casing

~.~ ~_ ~ " ~ [

[

Slate cill Panel No. 67 Factory-assembled panel, wood-framed of softwood, except for the hardwood window-cill. The details o f the panel-infill below the windows are shown in the figure. Single-glazed windows. Built in 1955.

,Wood cill Liqhtweigh~ "inner leaf

Tested in 1955-6. 24-h mean U-value = 0.61 B.t.u./ft 2 h °F Mean U-value for spandrel = 0.31 B.t.u./ft 2 h °F

Wood frame

Windows with in'l'ernal wood Distribution of heat-flow

Alu?nini.um panel 3~' Asbes~s board Tested in 1955-6.

panel

i °,, ~i!

Osmf~"f°i I rboard

rock wool quilt

Part of wall

Area as Proportion of proportion of total heatwhole wall flow (%)

(%)

Glass and aluminium window framing Spandrel panel

65 35

83 17

A . W. P r a t t

168

Panel No. 69 The same as panel No. 68, but with double windows. A wooden frame was built on to the inside of the metal window-frame, and glazed from inside with wooden beads, giving an air-space 2 in. wide.

S -I-eel column with olast"er .casing

Aluminium , window f r a m e

t

Added

Mean thermal transmittance = 0-57 B.t.u,/ft 2 h °F Estimated thermal transmittance of spandrel panel - 0.25 B.t.u./ft 2 h °F Distribution of heat-flow

Part of wall

Area of Proportion of proportion of total heatwhole wall flow (%)

Glass, including frames Spandrel panel

0-55 0.45

8I 19

wooden window frame wi~

Dense- concrete' panels boiled ~(~s÷eel column

inner 91azir~j

Ligh+wegh÷

Sla+e cill

'inner leaf

Tested 1956-7. 24-h mean U-value Day-time mean U-value Night-time mean U-value Mean U-value for spandrel

Panel No. 71 Wood-framed single-glazed window, with 18 lights each 2 f t 2 in. x I ft 1 in. clear (68 per cent of wall area glazed). Built January 1939. J

B.t.u./ft ~ h °F 0.31 0.15 0.36 0-31

I

Distribution of heat-flow Area as Proportion of proportion of heat.flow ( ~ ) * total (%)

Part of wall

Glass (double-glazed) Wood window frame Spandrel panel Column (above window-ciil)

49 10 35

52 8 26

12

14

Tested February-March 1939. Mean thermal transmittance, 6 February to 26 March

= 0.58 B.t.u./ft 2 h °F

* Based on projected area of panel.

Panel No. 70 Experimental curtain-wall with wood-framed windows. Built 1955.

~

W

Panel No. 72 Wood-framed window, exactly similar to panel 71, but doubleglazed. Built January 1939.

Wooden droppers wifh aluminium T sec4"ion onfaces ood-framed

windows

Wood-wool /

"~.L..,J I ~ j a = v , f Wood cill ,~,~r ~^f 4 ~"~.. ~ A l u m i n i u m - f o i l backed ........ . j~'~J ~fplosterboclrd inner leaf Aluminium cill i ~ Aluminium dropper j "~

Tested 1955-6.

Tested in February-March 1939. Mean thermal transmittance, 6 February to 26 March

= 0-30 B.t.u./ft 2 h°F

169

Thermal Transmittance o f Walls

~ ¢ t i o n of

Fromin9

Panel No. 73 Teak frame with four panes, each approx. 3it 9in. square, of'Insulight' sealed double-glazed units. Each unit made of ¼ in. plate glass with ¼ in. air-space, set into frame with mastic bedding and held by teak beads. Wall erected 17 June 1960.

I

Tested in 1960-1. Mean night-time U-value = 0.48 B.t.u./ft 2 h °F

On donne les rrsultats de mesures prises du flux de chaleur h travers des murs exposrs au temps ~t exposition allant de l'exposition abritre h l'exposition modrrre dormant directement au nord. Un grand nombre des rrsultats sont publirs pour la premirre fois et sont prrsentrs avec de~ donnres d'essai drj~t disponibles dans la littrrature pour donner un rrsum6 complet des travaux effecturs en Grande-Bretagne sur la transmission de la chaleur en hiver ~t travers des murs h exposition naturelle. On se propose de discuter des rrsultats dans un expos6 suivant. Der Artikel gibt die Ergebnisse von Messungen des W~irmestroms durch W~inde, die dem Wetter in geschiitzter bis m~Big freier Lage ausgesetzt sind und genau nach Norden gehen. Viele dieser Ergebnisse werden zum ersten Male ver~ffentlicht und mit in der Literatur bereits zur Verffigung stehenden Prfifdaten vorgelegt, und bieten demnach eine komplette Zusammenfassung der in GroBbritannien durchgeffihrten Arbeiten fiber W~irmedurchgang im Winter durch Natureinflfissen ausgesetzte W~inde. Eine Besprechung der Ergebnisse in allen Einzelheiten ist ffir eine weitere Abhandlung vorgesehen.