A DISCUSSION ON THE DESIGN PRINCIPLES OF A PATENTED ... · A DISCUSSION ON THE DESIGN PRINCIPLES OF A PATENTED PORTABLE DIRECT SUNLIGHT LIGHT-DUTY UNIVERSAL HELIODON MOUNTED ON A

International Journal on Architectural Science, Volume 8, Number 4, p.98-113, 2011

__________________________________________________________________________________________________

98

A DISCUSSION ON THE DESIGN PRINCIPLES OF A PATENTED

PORTABLE DIRECT SUNLIGHT LIGHT-DUTY UNIVERSAL HELIODON

MOUNTED ON A CAMERA TRIPOD

K.P. Cheung

Department of Architecture, The University of Hong Kong, Hong Kong, China

(Received 10 October 2012; Accepted 11 January 2013)

ABSTRACT

Heliodons are physical tools developed to study and test the solar performance of physical building models by

simulating direct sunlight to impinge onto building models, for various desirable combinations of latitude, day,

and time.

In the learning process of architecture students and in professional architecture design processes, small and light

weight working models are always made first for studying various design objectives including solar

performance. The preferred one or two optional designs will then be further developed and formed into physical

models of larger size with more details, and developed into computational models, for in-depth and detailed

study of various design objectives including solar performance.

This paper discusses the design principles of a patented portable direct sunlight light-duty universal heliodon

mounted on a camera tripod which is affordable, easily stored up and assembled for use. The patented heliodon

is useful for testing the direct sunlight effect of small foam board or card board models of buildings, or building

components.

The “universal” capability of a heliodon attributes to its adjustment flexibility to test the model for all simulated

desirable combinations of latitude, day, and time, for any simulated place in the world where the actual building

will be built, from most north places to most south places. The patented heliodon was initially designed for

outdoor operation, using “direct sunlight” available at any place, any time in the world, as the light source, to

avoid light source error of artificial light. Furthermore, this heliodon can be mounted on a camera tripod

commonly used for holding cameras, eliminating the special provision of a heliodon stand which is a key factor

affecting the cost and storage space, and hence the portability and affordability of the heliodon.

1. INTRODUCTION Heliodons are physical tools developed to study

and test the solar performance of building models

by simulating direct sunlight to impinge onto

building models, for various desirable

combinations of latitude, day, and time.

The adjustable variables of heliodons are [1-3]:

- the latitude variable, which defines the sun

paths in relation to the geographical location

[Fig. 3, Fig. 3a],

- the seasonal variation, which relates to the

declination of the sun on a given day [Fig. 3,

Fig. 3a, Table 1],

- hourly change of the sun from East to West

during the day.

The heliodons developed so far could be broadly

categorized into two categories:

- a fixed light source (single lamp or multiple

lamps) [2,7-9], or a moving light source [1,2]

with the building model rotated and/or tilted,

- the building model is placed horizontally and

stationary, and the light source moves [4-6,

10-13].

Since the first heliodon developed in 1931 [1, Fig.

1], traditionally heliodons are tools located in

architectural school laboratories, occupying a

room, and not convenient for practicing architects

to use, because it takes time and effort to transport

the building models to the laboratories.

For convenient and popular use of heliodons, the

size, portability, and affordability of the heliodon

are also important factors. A patented portable

direct sunlight light-duty universal heliodon [14,

Fig. 2] addressing these issues has been developed,

and its design principles are discussed in this paper.

International Journal on Architectural Science

__________________________________________________________________________________________________

Fig. 1: Dufton & Beckett Heliodon of 1931 [1, 2, 16, Table 1] Note that d is the solar declination angle [Fig. 3, Table 1], and L is latitude in Northern Hemisphere shown in the above

configuration.

Fig. 2: The patented portable direct sunlight

light-duty universal heliodon [14] - View

showing outdoor operation using direct

sunlight as the light source, mounted on a

camera tripod set at two possible

combinations of latitude, day, and time:

[Fig. 7, Fig. 4, Fig. 5, Fig. 8]

- For Northern Hemisphere : 10 am,

Apparent Solar Time, 45 degree latitude,

5 May or 7 August, noting that the top

point of the globe is the north pole [Fig.

3]

- For Southern Hemisphere : 2 pm,

Apparent Solar Time, 45 degree latitude,

4 Feb or 7 November, noting that the top

point of the globe is the south pole [Fig.

3a]

99


__________________________________________________________________________________________________

Table 1: Mean value of the solar declination [Ref. 15, for l99l, noon UT (GMT), adapted from Ref. 16]

DAY JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC

1 -23 01 -17 10 -07 40 +04 27 +15 01 +22 02 +23 08 +18 04 +08 22 -03 06 -14 22 -21 46

2 -22 56 -16 53 -07 17 +04 50 +15 19 +22 10 +23 03 +17 49 +08 00 -03 29 -14 41 -21 55

3 -22 51 -16 35 -06 54 +05 14 +15 37 +22 17 +22 59 +17 34 +07 38 -03 53 -15 00 -22 04

4 -22 45 -16 17 -06 31 +05 36 +15 54 +22 24 +22 54 +17 18 +07 16 -04 16 -15 18 -22 13

5 -22 38 -15 59 -06 08 +05 59 +16 11 +22 31 +22 49 +17 02 +06 54 -04 39 -15 37 -22 20

6 -22 31 -15 41 -05 45 +06 22 +16 28 +22 38 +22 43 +16 46 +06 32 -05 02 -15 55 -22 28

7 -22 24 -15 23 -05 22 +06 45 +16 45 +22 44 +22 37 +16 29 +06 09 -05 25 -16 13 -22 35

8 -22 16 -15 04 -04 59 +07 07 +17 02 +22 50 +22 30 +16 12 +05 47 -05 48 -16 30 -22 42

9 -22 08 -14 45 -04 35 +07 30 +17 18 +22 55 +22 23 +15 55 +05 24 -06 11 -16 48 -22 48

10 -21 59 -14 25 -04 12 +07 52 +17 34 +23 00 +22 16 +15 38 +05 01 -06 34 -17 05 -22 54

11 -21 50 -14 06 -03 48 +08 14 +17 49 +23 04 +22 08 +15 20 +04 39 -06 56 -17 22 -22 59

12 -21 41 -13 46 -03 25 +08 36 +18 05 +23 08 +22 00 +15 02 +04 16 -07 19 -17 38 -23 04

13 -21 31 -13 26 -03 01 +08 58 +18 20 +23 12 +21 52 +14 44 +03 53 -07 41 -17 54 -23 08

14 -21 21 -13 06 -02 37 +09 20 +18 35 +23 15 +21 43 +14 26 +03 30 -08 04 -18 10 -23 12

15 -21 10 -12 45 -02 14 +09 41 +18 49 +23 18 +21 34 +14 07 +03 07 -08 26 -18 26 -23 15

16 -20 59 -12 25 -01 50 +10 03 +19 03 +23 21 +21 24 +13 48 +02 44 -08 48 -18 41 -23 18

17 -20 47 -12 04 -01 26 +10 24 +19 17 +23 23 +21 14 +13 29 +02 21 -09 10 -18 56 -23 21

18 -20 35 -11 43 -01 02 +10 45 +19 30 +23 24 +21 04 +13 10 +01 57 -09 32 -19 10 -23 23

19 -20 23 -11 21 -00 39 +11 06 +19 43 +23 25 +20 53 +12 51 +01 34 -09 54 -19 25 -23 25

20 -20 10 -11 00 -00 15 +11 27 +19 56 +23 26 +20 42 +12 31 +01 11 -10 16 -19 38 -23 26

21 -19 57 -10 38 +00 09 +11 47 +20 08 +23 26.4 +20 31 +12 11 +00 47 -10 37 -19 52 -23 26.3

22 -19 44 -10 17 +00 33 +12 07 +20 21 +23 26 +20 19 +11 51 +00 24 -10 58 -20 05 -23 26.4

23 -19 30 -09 55 +00 56 +12 28 +20 32 +23 26 +20 07 +11 31 +00 01 -11 20 -20 18 -23 26.1

24 -19 16 -09 33 +01 20 +12 47 +20 44 +23 25 +19 55 +11 11 -00 23 -11 41 -20 30 -23 25

25 -19 01 -09 10 +01 44 +13 07 +20 55 +23 24 +19 42 +10 50 -00 46 -11 01 -20 42 -23 24

26 -18 46 -08 48 +02 07 +13 27 +21 05 +23 22 +19 29 +10 29 -01 09 -12 22 -20 54 -23 22

27 -18 31 -08 26 +02 31 +13 46 +21 16 +23 20 +19 16 +10 09 -01 33 -12 42 -21 05 -23 20

28 -18 15 -08 03 +02 54 +14 05 +21 26 +23 18 +19 02 +09 47 -01 56 -13 03 -21 16 -23 18

29 -17 59 +03 18 +14 24 +21 35 +23 15 +18 48 +09 26 -02 19 -13 23 -21 26 -23 15

30 -17 43 +03 41 +14 42 +21 44 +23 11 +18 34 +09 05 -02 43 -13 43 -21 36 -23 11

31 -17 27 +04 04 +21 53 +18 19 +08 43 -14 02 -23 07

Note: Declination to north of the Equator is positive, to south is negative; thus for 11 Jan l99l, solar declination

angle was 21 deg 50 min south of the Equator.

2. THE DESIGN PRINCIPLES OF THE

PATENTED PORTABLE DIRECT

SUNLIGHT LIGHT-DUTY UNI-

VERSAL HELIODON

The Dufton & Beckett Heliodon of 1931, [1, Fig. 1]

which is well illustrated and discussed in many

books, and the patented portable direct sunlight

light-duty universal heliodon [Fig. 2], are in fact

both designed on the same basic solar-geographical

principles listed below. The patented heliodon now

reported, however has a more extensive coverage

on application ranges, exhibiting its “universal”

capability:

- The components simulate the sun-earth

system for Northern Hemisphere [Fig. 3].

However, in the patented heliodon now

reported, the sun-earth system for Southern

Hemisphere is also simulated [Fig. 3a].

- It is assumed that sunlight is practically

parallel, and impinges at same angles onto the

buildings,and hence building models, located

at surface of earth, and fictitiously at the

centre of the earth, because the distance of the

earth from the sun (about 150 million km) is

much greater than the diameter of the earth

(about 12,756 km), and the diameter of the

sun (about 1,380,000 km), in the ratio of

about 117590:1:108.

- The day scale surface of The Dufton &

Beckett Heliodon of 1931 [1, Fig. 1], shows

the simulated days for Northern Hemisphere

application, and the lamp holder and the day

scale is detached from the model platform

100


__________________________________________________________________________________________________

base frame. However, in the patented

heliodon now reported [Fig. 1, Fig. 4, Fig. 5,

Fig. 6], the simulated days are marked on the

day scale for both Northern Hemisphere

application, and Southern Hemisphere

application, and the day scale is integrally

attached to the model platform base frame.

For both heliodons, the straight lines marking

the various days, hence the corresponding

solar declination angle [15, 16, Table 1] are

set parallel to the axis of rotation of the model

platform; the same axis being the simulated

earth axis, the axis of rotation for change of

time of a day [Fig. 1, Fig. 2, Fig. 3, Fig. 3a,

Fig. 7, Fig. 8, Fig. 9].

- Apparent solar time is used as the basic time

scale. However, in the patented heliodon now

reported, the outer circular time scale ring is

for Apparent Solar Time indication. Also an

additional inner time scale ring is provided for

local standard time indication, following

established adjustment procedures [10,17,

Table 2, Fig. 15]. In both time scales, the

leading hour number is for use in Northern

Hemisphere application, and the following

hour number is for Southern Hemisphere

applications, thus, “10/14” means 10 am for

Northern Hemisphere application and 14:00,

or 2 pm for Southern Hemisphere application

[2,7,10,15, Fig. 7, Fig. 11, Table 2, Fig. 15].

- The model platform of The Dufton & Beckett

Heliodon of 1931 [1, Fig. 1], is basically set

for Northern Hemisphere. However, in the

patented heliodon now reported, the model

platform can be set to any desirable latitudes

of both the Northern Hemisphere and the

Southern Hemisphere [Fig. 1, Fig. 2, Fig. 7,

Fig. 8, Fig. 9].

- The model is tilted and moved during

heliodon operation.

- The light source used in The Dufton &

Beckett Heliodon of 1931 [1, Fig. 1], is

commonly an artificial lamp placed

sufficiently far away from the heliodon, yet

giving sufficient illumination onto the

building model being tested. However, in the

patented heliodon now reported, direct

sunlight which is moving, is the preferred

light source. Because of its portability and its

integral provision of the day scale onto the

rotating simulated earth-latitude-time system

assembly, NOW forming an integrated

simulated earth-latitude-time-DAY system

assembly, all mounted on a camera tripod,

will enable quick, efficient, and accurate

operation procedures to be carried out,

yielding accurate results of good light quality.

[Fig. 2, Fig. 7, Fig. 8, Fig. 9, Fig. 9a, Fig. 10]

Of course, an artificial light source can be

used for the patented heliodon now reported

[Fig. 12], but errors will result, because no

artificial light source can truly simulate direct

sunlight. Note that in the photos showing the

operation of the patented heliodon, the

latitude scale component of the patented

documents [14, Fig. 2] has been replaced by

an enhanced latitude component [Fig. 9, Fig.

9a, Fig. 11, Fig. 11a, Fig. 12], based on the

same solar-geographical principle.

Table 2: [adapted from Ref. 10] Adjustment for Local Standard Time (LST) : Illustration on the steps to

adjust the Inner time ring of the patented heliodon to read Local Standard Time RELATIVE TO

Apparent Solar Time (AST), shown by the outer time ring

Apparent solar time of local meridian of Hong Kong University

at 114 deg.8 min. East

12:00 noon (AST) 12:00 noon (AST)

Equation of Time (if slow, add; if fast, subtract) [ 17, Table 3] 8 Nov

16.3 min(sun fast)

20 Feb

13.8 min (sun slow)

Mean Solar Time of Meridian [17] 11:43.7 [a.m.] 12:13.8 [p.m.]

Correction for difference between local meridian (114 deg.8

min. East) of Hong Kong university and the related time zone

meridian at 120 deg. East at rate of 1 deg.=4 min. (If standard

time zone meridian lies to West, subtract the correction, if to

East, add) [17]

23.5 min 23.5 min

Hong Kong Standard Time (watch time, or mobile phone time) 12:7.2 [p.m.] 12:37.3 [p.m.]

For example, to read Hong Kong Standard Time at 8 Nov, the “12:7.2” mark of the Inner LST Time Scale Ring of the

heliodon has to be adjusted to match the “12:00 noon” mark of the Outer AST Time Scale Ring.

To read Local Standard Time (LST) on the Inner Circular Time Scale Ring, RELATIVE TO Apparent Solar Time (AST)

read by the Circular AST Outer Time Scale ring : For the day 20 Feb, the “12:37.3” mark of the Inner LST Time Scale Ring

[i.e. Hong Kong Standard Time] of the heliodon has to be adjusted to match the “12:00 noon” mark of the Outer AST Time

Scale Ring [Fig. 15].

101


__________________________________________________________________________________________________

Table 3: Mean value of the equation of time, in minutes at Apparent Solar noon [adapted from The

Nautical Almanac 1991, HMSO, UK. Ref. 16]

DAY JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC

1 3.4 13.6 12.5 4.0 2.9 2.3 3.7 6.3 0.1 10.2 16.4 11.2

2 3.9 13.7 12.3 3.7 3.0 2.2 3.9 6.3 0.2 10.5 16.4 10.7

3 4.3 13.8 12.0 3.4 3.1 2.0 4.1 6.2 0.5 10.8 16.4 10.4

4 4.8 13.9 11.8 3.1 3.2 1.8 4.3 6.1 0.8 11.1 16.4 10.0

5 5.2 14.0 11.6 2.8 3.3 1.7 4.5 6.0 1.2 11.5 16.4 9.6

6 5.7 14.1 11.4 2.5 3.4 1.5 4.6 5.9 1.5 11.7 16.4 9.1

7 6.1 14.1 11.2 2.3 3.5 1.3 4.8 5.8 1.8 12.0 16.3 8.7

8 6.6 14.2 10.9 2.0 3.5 1.1 5.0 5.7 2.2 12.3 16.3 8.3

9 7.0 14.2 10.7 1.7 3.6 0.9 5.1 5.6 2.5 12.6 16.2 7.8

10 7.4 14.2 10.4 1.4 3.6 0.7 5.3 5.4 2.9 12.9 16.1 7.4

11 7.8 14.3 10.2 1.2 3.7 0.5 5.4 5.3 3.2 13.1 16.0 6.9

12 8.2 14.3 9.9 0.9 3.7 0.3 5.5 5.1 3.5 13.4 15.9 6.5

13 8.6 14.2 9.6 0.6 3.7 0.1 5.7 4.9 3.9 13.6 15.8 6.0

14 8.9 14.2 9.3 0.4 3.7 0.1 5.8 4.8 4.3 13.9 15.6 5.5

15 9.3 14.2 9.1 0.1 3.7 0.3 5.9 4.6 4.6 14.1 15.5 5.1

16 9.7 14.1 8.8 0.1 3.7 0.6 6.0 4.4 5.0 4.3 5.3 4.6

17 6.0 14.1 8.5 0.3 3.7 0.8 6.1 4.2 5.3 14.5 15.1 4.1

18 10.3 14.0 8.2 0.6 3.6 1.0 6.2 3.9 5.7 14.7 14.9 3.6

19 10.6 13.9 7.9 0.8 3.6 1.2 6.3 3.7 6.1 14.9 14.7 3.1

20 10.9 13.8 7.6 1.0 3.5 1.4 6.3 3.5 6.4 15.1 14.5 2.6

21 11.2 13.7 7.3 1.2 3.5 1.6 6.4 3.2 6.8 15.3 14.2 2.1

22 11.5 13.6 7.0 1.4 3.4 1.9 6.4 3.0 7.1 15.4 14.0 1.6

23 11.8 13.4 6.7 1.6 3.3 2.1 6.5 2.7 7.5 15.6 13.7 1.1

24 12.0 13.3 6.4 1.8 3.3 2.3 6.5 2.5 7.8 15.7 13.4 0.6

25 12.3 13.2 6.1 2.0 3.2 2.5 6.5 2.2 8.2 15.9 13.1 0.1

26 12.5 13.0 5.8 2.2 3.1 2.7 6.5 1.9 8.5 16.0 12.8 0.4

27 12.7 12.8 5.5 2.3 3.0 2.9 6.5 1.6 8.9 16.1 12.5 0.9

28 12.9 12.6 5.2 2.5 2.8 3.1 6.5 1.4 9.2 16.2 12.2 1.4

29 13.1 - 4.9 2.6 2.7 3.3 6.5 1.1 9.5 16.2 11.8 1.9

30 13.3 - 4.6 2.8 2.6 3.5 6.4 0.8 9.9 16.3 11.5 2.3

31 13.4 - 4.3 - 2.5 - 6.4 0.4 - 16.4 - 2.8

Note: Apparent Solar Time + Equation of Time = Mean Solar Time (fictional). The bold faced numbers

indicate days in which the sun is slow, [25 Dec -15 April, 14 Jun-1 Sept] and normal fonts indicate days in

which the sun is fast [2 Sept-24 Dec, 16 Apr-13 Jun].

102


__________________________________________________________________________________________________

Fig. 3: The sun-earth system primarily set for Northern Hemisphere - Solar Geometric Parameters

Illustrated on the Globe shown for noon time of Apparent Solar Time System [7, 14]. For studying places

on Southern Hemisphere, it is advisable to rotate the diagram and replace the model platform to the

desirable latitude of Southern Hemisphere, so that the South Pole is at the top of the page.

Notes:

1. N-S is the axis of the earth for Northern Hemisphere. S-N is the axis of the earth for Southern Hemisphere.

2. In the diagram L is drawn equal to L’ for minimizing lines on the diagram, i.e. L=L’=45 degree.

3. For Northern Hemisphere: At latitude L, the horizontal plane is making an angle φ= L with the N-S axis if

the earth. At Equator, L=L’0, the horizontal plane is normal to the equatorial plane, and parallel to the N-S

axis. At North pole, L=90 degree, the horizontal plane is parallel to the equatorial plane, and normal to the

N-S axis.

4. For southern Hemisphere: At latitude L’, the horizontal plane is making an angle φ= L’ with the S-N axis of

the earth. At Equator, L’=L=0, the horizontal plane is normal to the equatorial plane, and parallel to the S-N

axis. At South pole, L’=90 degree, the horizontal plane is parallel to the equatorial plane, and normal to the

S-N axis.

103


__________________________________________________________________________________________________

Fig. 3a: The sun-earth system- primarily set for Southern Hemisphere - Solar Geometric Parameters

Illustrated on the Globe shown for noon time of Apparent Solar Time System [7, 14]. For studying places

on Northern Hemisphere, it is advisable to rotate the diagram and replace the model platform to the

desirable latitude of Northern Hemisphere, so that the North Pole is at the top of the page.

Notes:

1. S-N is the axis of the earth for Southern Hemisphere. N-S is the axis of the earth for Northern Hemisphere.

2. In the diagram L’ is drawn equal to L for minimizing lines on the diagram, i.e. L’=L=45 degree.

3. For Southern Hemisphere: At latitude L’, the horizontal plane is making an angle φ= L’with the S-N axis of

the earth . At Equator, L’=L=0, the horizontal plane is normal to the equatorial plane, and parallel to the S-N

axis. At South pole, L’=90 degree, the horizontal plane is parallel to the equatorial plane, and normal to the

S-N axis.

4. For Northern Hemisphere: At latitude L, the horizontal plane is making an angle φ= L with the N-S axis of

the earth . At Equator, L= L’=0, the horizontal plane is normal to the equatorial plane, and parallel to the N-

S axis. At North pole, L=90 degree, the horizontal plane is parallel to the equatorial plane, and normal to the

N-S axis.

104


__________________________________________________________________________________________________

Fig. 4: The Front view of the patented heliodon assembly set at 12:00 Apparent Solar Time and 90

degree latitude, showing The combined N. Hemisphere-S. Hemisphere Day Selector of the patented

heliodon. For Northern Hemisphere application, the north pole is at the top of the globe [Fig. 3]. For

Southern Hemisphere application, the south pole is at the top of the globe [Fig. 3a]. See Fig. 8 for Right

Side View.

105


__________________________________________________________________________________________________

Fig. 5: The combined Northern Hemisphere-Southern Hemisphere Day Selector of the patented heliodon,

showing the principles of determining the marking positions of the day[s] onto the Day Selector scale [Fig.

4, Fig. 8, Fig. 6] in relation to the dimensions of the gnomon, and solar declination angle [Table 1]

corresponding to each day.

Fig. 6: The Design of Day Selector Scale using the sundial principle for setting the desirable day, showing

the trigonometric relationship of the actual height of the tip of the gnomon and solar declination angles

[Table 1, Fig. 4, Fig. 5, Fig. 8].

106


__________________________________________________________________________________________________

Fig. 7: The top view of the patented light duty universal heliodon [14, Fig. 2], set at 12:00 of Apparent

solar time, 90 degree latitude.

Notes:

1. The model platform can be adjusted to the desirable latitude angle, and locked. The north, south direction for

Northern Hemisphere and Southern Hemisphere are in opposite direction.

2. The OUTER Circular Apparent Solar Time ring is fixed, while the INNER Circular time ring can be turned,

following established steps [2, 7, 10, Table 2] to read local standard time

3. The globe is added to help users to understand the sun-earth system simulated. For Northern Hemisphere

application, the north pole is at the top of the globe [Fig. 3]. For Southern Hemisphere application, the south

pole is at the top of the globe [Fig. 3].

107


__________________________________________________________________________________________________

Fig. 8: Right Side view of the patented heliodon assembly [14, Fig. 1], set at 12:00 of Apparent solar time,

90 degree latitude, showing The combined N. Hemisphere-S. Hemisphere Day Selector. For Northern

Hemisphere application, the north pole is at the top of the globe [Fig. 3]. For Southern Hemisphere

application, the south pole is at the top of the globe [Fig. 3a]. See Fig. 4 for the Front View.

108


__________________________________________________________________________________________________

Fig. 9: Testing of a cardboard model using the

patented universal light duty heliodon mounted

on a camera tripod [14], placed outdoor, with a

weak state of direct sunlight of 1 Jan 2013, 3.15

pm, Hong Kong Local Time, as the light source,

set at two possible combinations of latitude, day,

and time: [Fig. 4, Fig. 5, Fig. 7, Fig. 8]

- For Northern Hemisphere : 10 am, Apparent

Solar Time, 45 degree latitude, 5 May or 7

August, noting that the top point of the globe

is the north pole [Fig. 3]

- For Southern Hemisphere : 2 pm, Apparent

Solar Time, 45 degree latitude, 4 Feb or 7

November, noting that the top point of the

globe is the south pole [Fig. 3a]

Note: In the above photo, the latitude scale of the

patented documents [14, Fig. 2] has been replaced

by an enhanced latitude scale [Fig. 9a, Fig. 11, Fig.

11a, 12], based on the same solar-geographical

principle.

Fig. 9a: The patented heliodon set for the

conditions mentioned in Fig. 9, showing

enlarged view of the components, with the

latitude scale of the patented documents [14,

Fig. 2] now replaced by an enhanced latitude

scale [Fig. 9, Fig. 11, Fig. 11a, Fig. 12], based on

the same solar-geographical principle.

Fig. 10: Enlarged view of the direct sunlight

effect on a cardboard model, tested by the

patented universal light duty heliodon mounted

on a camera tripod [14], placed outdoor, with a

weak state of direct sunlight of 1 Jan 2013, 3.15

pm, Hong Kong Local Time, as the light source,

set for the conditions mentioned in Fig. 9.

Fig. 11: Enlarged view of the Enhanced Latitude

Scale [Fig. 11a] of the demonstrated prototype

of the patented heliodon, which replaces the

same component shown in the patented

documents, [14, Fig. 2], both designed on the

same solar-geographical principle. The attitude

is set at 45 degree. Apparent Solar Time (AST)

is set at 10 a m for Northern Hemisphere, same

as 2 p m [i.e. 14 hour] for Southern Hemisphere,

in the outer time scale ring, which thus reads

“10/14” [Fig. 7]. Inner time scale ring, used for

setting Local Standard Time-LST [Table 2],

meets the outer AST time scale ring at the same

markings, as LST is not used in the test.

109


__________________________________________________________________________________________________

Fig. 11a: The Enhanced Latitude Scale [Fig. 11] of the demonstrated prototype of the patented heliodon,

which replaces the same component shown in the patented documents, [14, Fig. 2, Fig. 8] both designed

on the same solar-geographical principle.

Fig. 12: Illustration of setting up the patented portable direct sunlight light-duty universal heliodon [14],

incorporating Enhanced Latitude Scale [Fig. 11, Fig. 11a], indoor using a tungsten lamp as the light

source at 3 m from the heliodon, inheriting light source error on light quality and deviation from being

parallel.

110


__________________________________________________________________________________________________

Fig. 13: Testing of a cardboard model of a building façade using the patented universal light duty

heliodon mounted on a camera tripod [14], placed outdoor, with a strong state of direct sunlight of 5 Jan

2013, 2.45 pm, Hong Kong Local Time, as the light source, set at two possible combinations of latitude,

day, and time:

- For Northern Hemisphere : façade facing South, 10 am, Apparent Solar Time, 45 degree latitude, 22

Dec, Winter Solstice in Northern Hemisphere, noting that the top point of the globe is the north pole

[Fig. 3]

- For Southern Hemisphere : façade facing North, 2 pm, Apparent Solar Time, 45 degree latitude, 21

Jun, “Winter Solstice in Southern Hemisphere”, noting that the top point of the globe is the south pole

[Fig. 3a]

Fig. 14: Enlarged views (Front view at Left, Back Side view at Right) of direct sunlight effect on

cardboard model of a building façade using the patented universal light duty heliodon mounted on a

camera tripod [14], placed outdoor, with a strong state of direct sunlight of 5 Jan 2013, 2.45 pm, Hong

Kong Local Time, as the light source, set for the conditions mentioned in Fig. 13.

111


__________________________________________________________________________________________________

Fig. 15: Illustration on setting the Inner time

ring of the patented heliodon to read Local

Standard Time (LST) on the Inner Circular

Time Scale Ring, RELATIVE TO Apparent

Solar Time (AST) read by the Circular AST

Outer Time Scale ring : For the day 20 Feb, the

“12:37.3” mark of the Inner LST Time Scale

Ring [i.e. Hong Kong Standard Time] of the

heliodon has to be adjusted to match the “12:00

noon” mark of the Outer AST Time Scale Ring

[Table 2]. In the time rings, one small division

represents a difference of 5 minutes of time.

3. CONCLUSION

The Dufton & Beckett Heliodon of 1931, [1, Fig. 1]

used a separate day scale for holding the lamp

which simulates the sun and its varying positions

over the year, i.e. solar declination [Table 1],

allowing light source error, while the adjustable

earth-latitude-time system assembly is detached.

However the reported patented heliodon

incorporates an integral Day Selector Scale onto

the earth-latitude-time system assembly, NOW

forming an innovative integrated simulated

earth-latitude-time-DAY system assembly, all

mounted on a camera tripod. This assembly

makes the patented heliodon portable, conveniently

to be taken to anyway using various light sources,

primarily with sunlight as the light source for

obtaining accuracy of shadow boundaries and good

lighting quality over the tested model surfaces.

Since direct sunlight is practically parallel, using

artificial light source will induce the inheriting light

source error on light quality and deviation from

being parallel.

Since the components are demountable and can be

stored inside a box about the size of an A4 paper

[297 mm x 210 mm, OR 11.69 inch x 8. 27 inch ]

of 100 mm thick [ 4 inch thick] , and the common

camera tripod is used as the support, the reported

patented heliodon has demonstrated the

convenience of its storage and transportation, and

its affordability for students and architects.

It is expected that this reported patented heliodon

will help educate effectively the architecture and

building students, and will be a convenient,

portable and affordable tool to be used by the

building and architecture profession, and the

general public on solar architecture design, thus

arousing the general public in wider acceptance and

demand on more integration of solar design into

buildings, contributing to building a sustainable

world.

REFERENCES

1. A.F. Dufton and H.E. Beckett, “Orientation of

buildings-sun planning by means of models”,

Royal Institute of Building Architects Journal, p.

509 (1931).

2. K.P. Cheung, C.Y. Chu, L.M. Lo, C. Siu and S.K.

Sin, “A light duty universal direct sunlight

heliodon”, Architectural Science Review, Vol. 39,

No. 4, pp. 187-191 (1996).

3. T.A. Markus and E.N. Morris, Buildings, climate

and energy, Pitman, London, pp. 401-405 (1980).

4. S.V. Szokolay, Solar geometry, PLEA Note 1, c/o

Department of Architecture, The University of

Queensland, Australia, p. 54.

5. N.M. Lechner, “A new sun machine: A practical

teaching, design, and presentation tool”,

Proceedings of American Solar Energy Society, p.

145, Figs. 1,3,4,5 (1993).

6. Olgyay & Olgyay, Solar control & shading

devices, Princeton University Press, New York, pp.

26, 27, 42, 43 (1957).

7. K.P. Cheung and S.L. Chung, “A heavy duty

universal sunlight heliodon assembled from

precision machining tools”, Architectural Science

Review, Vol. 42, No. 3, pp. 189-196 (1999).

8. K.P. Cheung and S.L. Chung, “An elaboration on

the design and operation principles of a heavy duty

universal sunlight heliodon assembled from

precision machining tools”, Proceedings of ISES –

Solar World Congress, Jerusalem, 4-9 July 1999,

International Solar Energy Society (1999).

9. Laboratoire de Lumiere Naturelle, Programme

interdisciplinaire LUMEN, “Lumière naturelle et

énergétique du bâtiment”, Projet OFEN, The

Manual, Laboratoire d’Energie Solaire et de

Physique du Bâtiment EPFL, CH-1015

Lausanne,Switzerland, pp. 15-41 (1994).

10. K.P. Cheung, H.M. Kam, S.L. Chung and C.F.

Lam, “A 23-lamp heliodon”, Architectural Science

Review, Vol. 42, No. 1, pp. 49-53 (1999).

11. K.P. Cheung, “A table top heliodon developed for

use in an architect’s design studio”, International

Journal on Architectural Science, Vol. 2, No. 4, pp.

118-128 (2001).

112


__________________________________________________________________________________________________

http://www.bse.polyu.edu.hk/researchCentre/Fire_

Engineering/summary_of_output/journal/IJAS/V2/

p.118-128.pdf

12. K.P. Cheung, H.M. Kam and C.F. Lam, “A Multi-

Lamp Heliodon for Architectural Schools”,

International Journal on Architectural Science, Vol.

1, No. 1, pp. 46-58 (2000).



p.46-58.pdf

13. K.P. Cheung, and S.L. Chung, “A Table Top

Heliodon with a Moving Light Source for Use in

an Architect's Office”, International Journal on

Architectural Science, Vol. 3, No. 2, pp. 51-60

(2002).



p.51-60.pdf

14. Kwok Pun Cheung, US Patent No. US6523270 B1.

A Universal Heliodon-Sundial, patent issued by US

Patent Office on 25 February 2003.

http://hub.hku.hk/handle/10722/142203,

also searchable at

http://portal.uspto.gov/external/portal/!ut/p/

15. K.P. Cheung, “An alternative solar chart and its use

in a case study”, Architectural Science Review,

Vol. 40, No. 1, p. 24-30. (1997)

16. The Nautical Almanac l99l, HMSO, UK, pp.10-

253.

17. A.N, Strahler, Physical georgraphy. 6th

edition,

John Wiley and Sons, New York, pp. 83-85

(1975).

113

http://www.bse.polyu.edu.hk/researchCentre/Fire_Engineering/summary_of_output/journal/IJAS/V2/p.118-128.pdf









http://hub.hku.hk/handle/10722/142203

http://portal.uspto.gov/external/portal/!ut/p/

Documents

A DISCUSSION ON THE DESIGN PRINCIPLES OF A PATENTED ... · A DISCUSSION ON THE DESIGN PRINCIPLES OF A PATENTED PORTABLE DIRECT SUNLIGHT LIGHT-DUTY UNIVERSAL HELIODON MOUNTED ON A