No_2_August_1964 — Page 128

CONTINUOUS

HORIZONTAL DESTRUCTION

SKY COMPONENT

20

IS

EXTERNALLY REFLECTED- COMPONENT

AV. ANGLE OF ALTITUDE

OF E.R.C.

15 20

25

30

45 31.

30

AV. ANGLE OF ALTITUDE

OF I.R.C.

04 03 02 010 01 82 3

The corrected sky component is 2.7 X 0.83 = 2.2%.*

EXTERNALLY REFLECTED COMPONENT

The externally reflected com. ponent can be calculated by con- sidering the external obstructions visible from the reference point as a patch of 'sky' whose luminance is some fraction of that of the sky ob- scured. In other words, the 'equiva- lent sky component' is first calculat- ed by one of the methods already described and is then converted to the externally reflected component hy allowing for luminance of the obstructing sur- faces compared with the luminance of the sky. The luminance of

the reduced

*Note-In practice there is little to be gained by working to more than two significant figures.

IMPRESSIONS OF HONG KONG (From page 110)

the U.S., where labour and materials are commonly expensive, standar- dization and repetitive use of stock items is essential. This must be achieved through careful and exhaus- tive detailing. Stock items such as light fixtures or hardware tend to be fairly ugly in the U.S., while the opportunity to design individual items is expensive and rare.

Poor finish

Surprising as well in these specula. tive buildings is the generally poor quality of finishes, curiously more evident in simpler situations, such as where jamb meets plaster. Rough and finish carpentry seem to be of a

122

6-0"

REFERENCE

-POINT

Protractor No. 1

Section

Fig. 6 Building Research Station protractors

obstructions varies widely in prac. tice but, unless the actual value is known. it is assumed to be uniform. with a luminance of one-tenth of the average luminance of the sky. When using the protractors. it is as a rule sufficiently accurate to make this as sumption. i.e. to calculate the equivalent sky component and divide. by 10. Thus, in the example in Fig.

6:

1. cor

Readings on protractor responding to sight-lines drawn to the cill and the top of the obstruc- tion, are 2.9% and 0.2% Equivalent sky component=2.9- · 0.2=2.7%

Average angle of altitude = 14° Readings on auxiliary protractor 2 are 0.30 and 0.15 Correction 0.45

factor 0.30+0.15=

consistently high level. but only in more expensive buildings is some interest attempted in wood details. Particularly amusing is the square mileage of obviously cheap ochre paint, and the "electric noodles" which are everywhere stock to ceil- ings and walls.

Criticism of course comes easily in any situation. Constructive criticism would have been more difficult: for one visiting the Colonp many sur- prises are caused by unknown wrin- kies. There is much of great interest and high standard to be seen in Hong Kong. For example, resettle- ment blocks, which have won univer- sal interest and respect, are common- ly built at a cost of less than one- third of that required to build the most basic concrete parking garage in the U.S. The roads which loop

90° 60° 25°

MEAN ALTITUDE

REFERENCE POINT

"O* 30* 60*90*

Auxiliary Protractor No. 2 Plan

Equivalent uniform sky component for obstructed part of sky visible from reference point = 2.7 X 0.45 = 1.2% approx.

Assuming brightness of obstruc- tions to be one-tenth that of the uniform sky,

Externally reflected component=

= 0.12%.

1.2 10

When using the B.R.S. Sky Com- ponent Table and the Waldram Diagram modified for overcast sky, for obstructions below 20°. the equivalent sky component value is divided by 5 instead of 10. This is because the luminance of a densely overcast sky near the horizon is ap- proximately half the average sky luminance and this correction has already been incorporated in the B.R.S. Sky Component Table and the modified Waldram Diagram.

around the Peak, while not intended as speedways, represent a simple solution to traffic needs without carv- ing up the landscape (probably 30 per cent of Los Angeles's surface area is roadway). While not quite scheduled by computer, construction seems generally quick and up-to-date

What seems perhaps most surpris ing is that planners are apparently not given the economic or legislative means of guiding the growth of the city. Many American cities have learned how expensive it is to correct at a later date the results of not hav ing been able to plan ahead

The "Hot Harbour" and "Interpol" atmosphere of all the films etc. is disappointing to one anticipating a latter-day Chicago. Instead, Hong Kong remains uniquely beautiful.

THE HONG KONG & FAR EAST BUILDER—VOLUME 19. NUMBER 2