Computer-aided evaluation of the housing environments

Computer-aided evaluation of the housing environments

0198-971s 86 s3.00 + 0.00 CopyrIght c’ 1986 Per~amon Press Ltd Compur. Enr~rron L:rhan Systems Vol. IO. I‘;o. 3,4. pp. 197-210. 19% Primed in Great B...

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0198-971s 86 s3.00 + 0.00 CopyrIght c’ 1986 Per~amon Press Ltd

Compur. Enr~rron L:rhan Systems Vol. IO. I‘;o. 3,4. pp. 197-210. 19% Primed in Great Bntam All nghts reserved

COMPUTER-AIDED

EVALUATION ENVIRONMENTS-lCAHID

OF THE

HOUSING

AYBET$

Abstract-This paper deals with the development and environmental variables involved in designing the housing layout form. It is considered that the factors taken into consideration and the criteria used in the course of decision-making in creating and reshaping the residential environments should be systematically tested in the light of the needs and social goals of the community. As the main potential of the computer lies in the process of analysis and appraisal the main objective of this study is to evaluate the quality and performance of the physical environment by means of utilizing computer techniques.

INTRODUCTION

The continuing population increase and migration to large urban areas from rural and smaller urban areas aggravate the housing situation in the large cities, in some parts of which overcrowding and unfit housing are still current problems under treatment. In most cities existing housing areas seem to be unable to cope with the expected growth of urban population on the one hand, and on the other hand urban costs per capita rise with increasing urban size and the urban environment tends to deteriorate [l]. The immediate problem. therefore, appears to be where to accommodate this growth with associated facilities and services. and to provide a certain degree of environmental quality which will be above a predetermined level of acceptability in terms of environmental performance. Most of the physical environment is, to a large extent, a public good, so that the environment is affected considerably by the action of the government or local authority. Most aspects of the built environment are, thus, determined by the authority on behalf of the community. Therefore, it is the authority which has to choose locations, standards, types and quantities through the decision-making process in order to direct further growth. In addition to residential developments undertaken by the authorities as fulfillment of their statutory obligations, commercial agencies also make some contribution as a profitable enterprise towards meeting housing demands. Therefore development control procedures become a major tool in creating a satisfactory residential environment to meet the demands of the community in maintaining a certain minimum degree of environmental quality. In most cases, the decisions for the location and type of residential development depend upon the costs, which are easily quantifiable and relate to physical infrastructure and economic investment. The question of benefits gained from and costs incurred by the housing development for a given number of population at alternative locations or with alternative layout forms is still an “unknown” factor which creates an important gap in the decision-making process. The evaluation process of housing development can be considered in two distinct parts: (i) input, and (ii) output. The input consists of the commodities and resources to be planned, invested in and produced. The output side consists of the housing environment as a whole for the performance of a wide variety of physical and social functions. Most of the plan evaluation methods currently in use are concerned with the input, as economic and financial costs of investment are easily quantifiable. It is considered that the main approach should be the evaluation of output in relation to a set of the objectives proposed, the criteria adopted and the information specified. The computer-aided method of evaluation of the quality and performance of the housing environment is aimed at the selection of a site for development, and a layout form amongst a number of attainable alternatives which will maximize the ratio of output benefits to input costs. URBAN

HIERARCHY

A “housing estate” (or a residential unit) is a component part of a larger residential area (or a neighbourhood unit), large enough to support local community facilities. This “residential area” tTo avoid delay this paper has been published without $The author can be contacted via the Journal Editor.

the author’s

197

corrections.

CAHID AYBET

198

is, in fact, a component part of a town, a city or a large urban complex, and maintains functional links with central area facilities and employment areas. The town or city is, in turn, a part of a region consisting of urbanized and rural areas and having physical, economic and social characteristics of its own. All the factors affecting the quality of housing environment belong to the various levels of this hierarchy. One factor may be assessed on regional or sub-regional scale (e.g. journey to work), another one may require urban scale evaluation (e.g. accessibility to central area facilities, water and air pollution). Another factor may necessitate a neighbourhood scale evaluation (e.g. noise, visual quality), and some factors can only be assessed on residential unit scale (e.g. privacy, maintenance), while other factors are attached to dwelling unit (e.g. daylight, sunlight). In the process of evaluation of the factors affecting the general quality of a housing environment, there appears to be a series of hierarchical levels which can be briefly identified as: (i) (ii) (iii) (iv) (v)

regional, sub-regional level (metropolitan region, conurbation); urban level (town, city, metropolis); residential area level (neighbourhood, residential district); residential unit (housing estate); dwelling unit.

The computer-aided method developed for the purpose of the environmental evaluation of housing layout form is concerned with the factors related to neighbourhood, or housing estate and dwelling unit levels of this hierarchy. In the design field the main potential of the computer lies in the process of analysis and appraisal [2]. It is, therefore, considered that a computer-aided method for the evaluation of the quality and performance of the housing environment and the optimization of the housing layout form should be used in the analysis and appraisal stages of the design activity. For any large scale housing development, there are a number of possible solutions. The major problem is the selection of the most suitable one, which can be achieved by an early exploration of all the attainable alternatives-as alternative locations for development and alternative layout designs on these sites, considering the most important variables which control and determine the quality and performance of the environment. These variables should be weighted against each alternative’s population potential, space provision and development cost. This method is intended to evaluate various alternative schemes at the design stage in terms of their functional content and the environmental qualities which they can provide. The method is also flexible enough to absorb some modifications for application in different areas with specific problems or significant features. This housing evaluation and optimization method is intended to form an integral part of the decision-making process with regard to the type, location and average environmental quality of a housing development. The main function of such a program would be to explore the feasibility of all the possible alternatives on the basis of the information specified, and to choose one solution which represents the optimal achievement of the criteria adopted and meet the operational demands of the objectives set out. EVALUATION

FRAMEWORK

The method described represents an analytical approach to the spatial structure of the housing environment. It is assumed that all the dwelling units used in the layout design comply with the building regulations and other statutory requirements. The main concern of the approach is, therefore, to deal with the physical characteristics of the external environment. The evaluation process is not directly involved with the sociological implications of various layout forms. Evaluations are carried out by means of a set of “environmental variables” derived from the study of a number of factors which determine and control the quality and performance of the external housing environment. Environmental consequences of proposed layout forms are assessed and compared on the basis of their desirability in relation to specific objectives. Assessment of the environmental variables are made in relation to their physical measurement (in terms of distance. quantity, angle, intensity, frequency etc.). Weightings of the environmental variables are related to the space standards, the distribution of dwelling types and the total development costs, in order

Computer-atded

to establish the correlations of providing it.

between the environmental

EVALUATION

19Y

evaluation of housmg environments

quality, to be gained and the total costs

OF ENVIRONMENTAL HOUSING AREAS

QUALITY

IN

Since we design in order to create a better environmental quality in housing areas. definition of environmental quality becomes a critical issue. Environmental quality is a relative notion. It is related to perception and cognition of the environment [3]. Perception of environment. response and reaction to it. and environmental group preferences are the concepts to form a link between the psycho-social and physical environments. Sensory stimuli and cues which are derived by people from various aspects of the environment determine the degree of perceived environmental quality 141.

Appraisal methods of environmental quality currently in use have a common approach which is the principle of penalizing certain environmental aspects which apparently have shortcomings; measuring environmental quality involves the assessment of people’s preferences in their housing environment. This may change from one society to another. As the housing environment serves a variety of human functions and responds to human sensibility, evaluation of housing environment becom,es susceptible to abstract speculations. The environmental quality is understood, throughout this paper, as a concept which is determined by a combination of factors related to the performance of various functions. There are always a number of constraints which make it difficult to achieve a degree of environmental quality that may be regarded as satisfactory by the large majority of people. These constraints may be related to physical conditions of the site (topography, locational characteristics etc.) or economic problems (limited financial resources to implement the scheme), social problems obstructing the achievement of a balanced mixture of social groups or simply poor design quality. From this point of view, it is assumed that, in a housing environment, it would be possible to allocate some penalty points for a particular aspect of the physical environment which is apparently inadequate or insufficient with regard to satisfying residents’ requirements with its particular function [5]. ENVIRONMENTAL

VARIABLES

AND

INDICATORS

The nature of the surroundings of a dwelling unit has a fundamental influence on its desirability [6]. Environmental awareness of people-the degree to which residents are aware of the various features of their physical surroundings-is concerned with certain factors such as accessibility to local community facilities, traffic circulation, noise, privacy, daylight, sunlight, view, visual appearance and so on, which are functional concerns that contribute to the satisfaction derived from the environment in a housing area. These are the environmental variables which respond to the people’s operational demands in their everyday life. Several combinations of these variables control the environmental quality and also define the capacity of any particular aspect of the environment in meeting residents’ operational demands. In this study, only three environmental variables, which can be measured in physical terms on the layout design, have been included in the computer programme: (i) Accessibility to community facilities; (ii) privacy; and (iii) sunlight.

facilities-local

shopping, public transport,

social and health

Each environment variable is analyzed separately and an indicator representing this particular environmental aspect is developed. An environmental “indicator” is a scale indicating various degrees of environmental quality with regard to a particular environmental variable. It describes the operational efficiency of a certain aspect of the physical environment which relates directly to the degree of satisfaction derived from the environment. The indicators used in the program-accessibility, privacy and sunlight-are the

CAHID AYBET

200 Development

voriotions

Enviromentol

variables

Space ollocotion

Distribution

of dwelling

Fig. 1. Interaction of variables.

ones related to layout design. It is considered that many environmental deficiencies may be improved or avoided to a considerable extent by means of modifying the layout form to achieve a more suitable design. Environmental indicators, being based on the physical measurements, can be objectively quantified by using an “ordinal” scale of measurement which signifies an order of quality. Environmental quality with regard to each variable respectively, is measured by allocating certain ratings as penalty points within an ordinal scale. Each environmental indicator has a number of items classified in such a way that each class indicates a certain degree of environmental deficiency. The items included are weighted according to a scoring system. The purpose of this process is to distinguish the difference between the defects of greater and lesser significance in a specific way and thus to define the degree of severity of that particular environmental variable. Weighting system is not an arbitrary process, it is related to physical measurement of the environmental variable. The penalty points are allocated for each item according to the criteria set out in objective terms such as dimensions, distances and angles. Accessibility indicator

Accessibility indicator is based on the convenience and safety of pedestrian accessibility to local community facilities. Although increased car ownership in affluent communities has made the dependence on local services less important, there are always certain groups of people who cannot use cars. Existence of local community facilities also increases social contacts. Besides, today’s energy saving trends in community life encourage more pedestrian activity. The network of main pedestrian footpaths in a housing area (a residential district, neighbourhood, or housing estate) must provide the most convenient access to local facilities. In the accessibility indicator, penalty points are allocated on the basis of the distance of facilities from the houses (either from each dwelling unit or from each area unit) and safety and convenience of pedestrian access. In addition to distance and existence of road crossings on route to specify the Class A, B or C in the index, within classes B and C, penalty are given according to (i) indirectness of route, (ii) excessive gradient of main footpaths (Table I). Local facilities taken into consideration in the accessibility indicators are the services and facilities which are normally required in a district (or neighbourhood) centre, as listed below: Local shopping: a number of shops sufficient in size and variety to serve its vicinity within up to 800 m walking distance; Public transport:

access point to a public transport

service, (bus stop, suburban railway etc.);

Social facilities: meeting hall, public house. branch library, religious building; Health facilities: doctor’s surgery, public health and weifare service; Recreational

areas: recreational

open space. play grounds. park playing field;

D

C

B

A

high

Very

safety

qualily.

poor environmenlal

for pedestrians.

and

con-

qualily.

lack of convenience

environmental

siderahle

Poor

for pedestrians.

and safely

quality,

degree of convenience

environmental

satisfactory

Moderate

provided.

quality,

and convenience

environmental

degree of safety

Good

Classifcation

Local

.. _

transport

distance).

crossing.

Class “C”.

Dislances

to

crossing.

walking

facilities

pedcslrian

are

involves

facilities

as

in

road

as

no

5 min

public

800 m.

areas,

road

are

access

access involves

than

distance)

than

recreational farther

access

pedestrian

community

distance)

walking

road

areas

“A”.

200 400 m.

pedestrian

within

than 400 m. (more

IOmin

farther

than

school,

are located

transport

(more

crossing.

recrealional

road

Class

access involves

communily

pedeslrian

IO

distance)

transport crossing.

shopping.

facilities

social

2. Local

crossing.

“B”,

Distances

no road

involves

I.

walking

in Class

school.

as in

4OW X00 m. (up lo IO mia walking

public

within

and internal

school, social facilities are

access involves

shopping.

(5 min

distance)

localed

2. Local

areas

IO shopping,

recreational

Distances

pedestrian

and

I

roads).

within

crossings

located

no road

on c&de-sacs

access involves

crossings

3. Pedestrian

(excluding

distance).

access point

facilities;

400 m. (5 min

social

within

school.

areas located

shoooine.

200 m. (3 min walking

2. Public

walking

recreational

I.

Table

I.

2

I

1 IO

x

1 IO

8

5

0

school

shopping

0

Primary

indicator

LCGdl

Accessibility

1 IO

8

7

5

0

3

transport

Public

1 IO

8

4

I

0

4

areas

Recreational

Social

branch

:o

8

4

0

5

hoilding

religious

library,

hall

(meeting

lacilitics

A

R

4

I

0

6

facilities

health

Puhhc

7

point\

pcll:‘lly

AWXlgc

? 2 c

202

CAHID AYBET

Primary school: provision of primary education and recreational facilities form an integral part of housing environment and proximity to school and amenities is measured as distances along the main pedestrian footpaths. Privacy indicator

The term “privacy” in this paper refers to visual privacy which is in general terms defined as not being overlooked. The need for privacy is related to (i) age, and (ii) social status, residents may have freedom from social contact and observation when these are not desired. Lack of adequate privacy in a housing area may be related to physical characteristics of the environment and may well be the result of poor design quality. There are mainly three major factors controlling the degree of privacy in housing: (a) privacy distance (between the housing blocks), (b) privacy barriers (landscaping), and (c) frequency of in-looking. Satisfactory level of privacy can be achieved as a design solution by using different levels, different location and orientation of windows, main footpaths and landscape elements for screening. Visual privacy from in-looking pedestrians on main footpaths is related to the distance between the footpath and the window, and the intensity of pedestrian flow. A dwelling unit having windows of habitable rooms on both sides is defined as “dual-aspect” dwelling and a dwelling unit having windows of habitable rooms only on one side is defined as “single-aspect” dwelling. Privacy standards are usually expressed as “privacy distances” which in fact refers to the distance between two dwellings overlooking each other (the distance between two rows of houses and blocks). Minimum privacy distances are: between two dual aspect type dwellings: 18 m; between main pedestrian way and dwelling facade with windows of habitable (Table 2).

rooms: 5 m.

Sunlight indicator

Adequate penetration of sunlight into the dwelling unit correlates considerably with the degree of satisfaction with the housing environment. The orientation of dwelling unit frontage is regarded as an essential factor in determining the duration of sunlight. It is assumed that all the dwelling units comply with the building standards to satisfy the minimum daylight reception requirements. The reception of sunlight in the dwelling unit is affected by: (i) block orientation; (ii) block spacing; (iii) form and height of building; (iv) existence of any obstruction; and (v) dwelling aspect type (dual aspect/single aspect). Block spacing for sunlight varies with orientation, but it is the privacy factor which determines block spacing in most cases. Spacing for sunlight also depends on block height whereas privacy is a constant distance. (Table 3). Sunlight duration is, in fact, directly related to the geographical location; but within a given geographical location, orientation, block spacing and site aspect factors play 2n important role. Orientation, block spacing, dwelling type and aspect are directly related to housing layout form and the density of development.

DEVELOPMENT

VARIABLES

Development variables are considered in three groups; (i) space allocation. (ii) distribution of dwellings, and (iii) development costs. Analysis of the development variables illustrates the allocation of land, spatial form of the development and the provision of floor space. (i) Space allocation variable deals with: (a) total land area and total number of persons to be accommodated (number and bedspaces gives the population potential of the scheme); (b) allocation of land for dwellings, public and private open space, car parking, roads and footpaths as square metres of land area, per dwelling unit and per bedspace (per person), and also as percentages

of distribution

of land area:

Computer-atded

d

e

203

evaluation of housing environments

u

c

tl

A

dclicicncy

qurrhty,

no wvir-

16 pcrnli~~ible.

cIIYIronnl‘xIal

S‘lllsbclory

quality,

cnvirwunenl,d

drliciwcy.

rnvironnwntat

umnc~ail

God

<‘lnxGlicalion

suniighl).

dwrtliag,

of

sunlight (awage

a day

rcccplion 2 hr

in

lhc

IIK

direcl

in

2 hr a day

sunhghr

(avcragc more lhitn

rcwption

sunlighl).

Sotimtklory

direct

dwelling,

Adcquale

westerly

facing

living

with specs or

I 3

0

I

dircclion

easterly

dwelling facing weslrrly

i

0

2

direction

caslerly

OF

type with

living-spaces

dwelling

Single-aspect

md~cator

lype

3. Sunhehc

Dual-aspect

‘fable

0rienIaliorr

i

0

3’

type with

northerly

dwelting

Dual-aspect

block

duration

I 3

0

4

-~

of sunlight

penelration

restricting and

or any

obslructron

spacing

Insulficien~

orienlelion

1 3

0

5

1ype with norlhcrty

dwelling

singlc-Ltspecl

6

points

penally

A%WIge

2 4

>

zz s

n

Computer-aided

evaluation

of housmg

environments

205

(c) space standards of the designed layout form; densities as persons per hectare, dwelling units per hectare and car parking spaces per hectare. floor space ratios and average dwelling size as persons (bedspaces) per dwelling. (ii) Distribution of dwellings variable deals with: (a) distribution of dwelling types. as total number and percentage of various types used in the layout. The dwelling types included in the program are bungalows (single-storey detached dwelling), houses (two-storey terraced houses with back gardens), maisonettes, flats in low-rise blocks. and flats in high-rise blocks; (b) distribution of dwelling sizes as number of apartments (rooms) and number of persons to be accommodated in a dwelling unit. (iii) Development

costs variable deals with:

(a) house erection which consists of construction costs of superstructure, substructure external works separately: (b) allowances as slope allowance and car space allowance in relation to site topography car parking density; (c) site development and servicing costs.

and and

All these development cost elements are considered as planned cost and checked against cost limit allowance as total costs and costs per dwelling unit. Net residential density, as average site area per dwelling and per person indicate the compactness and floor space ratio indicates the spatial form of the scheme. Distribution of dwelling types and sizes relates to the population structure in terms of household size. Development costs variable gives the designer the opportunity of analyzing cost consequences of alternative schemes, alternative layout forms accommodating similar number of population. EVALUATION

PROCESS

This is a planning and design stage appraisal which forms a basis for the designer to improve and finalize layout design. It can also assist the policy-makers and urban administrators in considering environmental quality factors in decision-making, whose decisions often condition and delineate the main guide lines on which the design decisions are based. The computer program package is a decision-making aid and a housing layout designoptimization tool. It provides immediate quantitative appraisal in response to input data of a site and layout form. The user has the ability of testing and evaluating environmental quality and performance of a housing scheme or a range of alternative layout designs for a particular development scheme. Figure 2 illustrates the evaluation process diagramatically, this clearly indicates that the computer is used in finding out about the development potential and the environmental output of a layout form designed manually. Input

The input data fall into two groups (i) non-locational data, (ii) locational data. Non-locational data consist of fixed data files for: (a) dwelling types: information and data for dwelling type and sizes, number of habitable rooms, number of persons per dwelling, dimensions, number of storeys and dwelling aspect of each type; (b) space standards: information and data regarding environmental criteria for accessibility, privacy and sunlight variables. space standards for environmental factors; (c) development costs: information and data for development cost per unit and cost limit al!owances. Fixed data files form a data-base which should be updated as the changes in standards, types and cost limits occur from time to time. Feedback of experience gained by previous applications of the program is also a valuable source of information. Locational data consists of project files which contain information specific to the scheme to be tested. These are data files for: (a) site: data for site boundaries, and main distance from site to location of certain community facilities. site topography; (b) development requirements: data for

CAHID AYBET

206

(

c Non - locational ( data - base)

Start

)

Data Input 1 ddta

Locational data Project data files Site, data related sate conditions

to

-I Computer Analysis

of development

program

variables

in relation

runs Analysis

to development

of enwronmental

variables

variables

Optimum layout form

Fig. 2. Evaluation

process

required population size, number of dwellings, dwelling types to be used; (c) layout form: data for geometric description of the designed housing layout form; this information is usually given by means of a digitizer used on the manually designed layout. output Output consists of the appraisal of the quality and the performance of the housing environment. The interacting factors involved in the evaluation process are (i) development variables, (ii) environmental variables, and (iii) layout-form. On a given site and site conditions the program will show what degree of environmental quality the layout form provides in relation to each environmental variable. Therefore. each environmental variable is tested individually on a given set of development variables so that the program enables the user to find out rapidly whether or not. or to what extent, any change in one or more of these development variables will affect the environmental variable tested. By running the program for each environmental variable in relation

Computer-aided

Scale I : 1250 Ske Layout. Layout

evaluation

of housing

Sate

: Test site

environments

Test site

207

Scale1

1500

Fig. 3. Computer hardcopy prints of the housing layout form at I : 1250 and I : 1500 scale as seen on the terminal screen.

to a permitted range of development variables, designers can improve the layout form until he obtains an optimum design solution. In the case of a number of alternative layout designs on a given site, the program shows the set of development variables and the level of environmental quality and performance provided by each

Layout

: Development

Layout

cost

Areas ( sq. m

Cast plan

Cast limit allawance

Hause erection Superstructure 776060 Substructure External works Slape allowance Cur space dansity allowance Covered car allawance Superstructure Site development Hardstandings

265431 30940 37378 30390

0

0

and servicing

Total

PaDwG

RerESP

%

GmundfCoa Total floor

3900.9 6940.4

36.2 81.7

8.3 18.0

15.7 35.4

Private 0 S Public 0 S

3816. I 7562.5

44.9 89.0

10.3 20.4

19.4 365

Faatpoths Mmor raads Major roads Site

6400

Total

25585

alLacation

I

Car spaces 0

: Space

800.0

9.4

2.2

4.1

1634.0 2750.0 .o

19.2 32.4 .o

4.4 7.4 .o

0.3 14.0 .o

19643.5

397724

BSP per DWG Floor space ratio

: Dwelling

Layout Typa

Pers

A.F.A.

NR

%

2 2’

:

t

26.40 21.32 15.40

9 28 18

10.59 21.18

K

6z

75 7

Zb.E

:

3?E 3.53

I

2 3

Is8

1% Total

Houses

Flats L rise

I

Cor space

Type

Fig.

4. Program

output.

:

I I.90 10.63

allocation

Hardstanding Car ports Garages

:: 0 0

I

53.1

loo.0

: :

4.4 2.3

allocation

Apts

Starers

231.

Net residential density DWG per hectare : 43.3 BSP per hectare : 186.4 32.6 CSP per hectare

Total 61

71.7:

24

28.2:

85

00.0:

,020 :o .O

computer hardcopy prints; allocation. dwelling allocation

analysis of three development and development costs.

variables,

space

CAHID AYBET

208

House

Rep

Code

X

Y

0 0 1 2 0 1 0 0 1 2 0 0 1 8 1 0 1 2 3 0 1 2 0 1 0 1 2 3 0 1

2442 2442 2442 2442 2442 2451 2451 2572 2452 2452 2452 2671 2572 2572 2452 2452 2452 2452 2452 2452 2442 2442 2442 2451 2451 2452 2452 2452 2452 2442 2442

86 84 82 78 73 66 69 51 45 41 37 30 41 46 48 52 76 72 68 64 110 106 102 98 92 109 165 101 97 121 125

27 34 41 45 49 54 60 73 76 88 84 90 90 95 102 106 84 80 76 72 72 76

10 2 3 3 3 4 4 5 6 6 6 7 : 9 9 10 10 10 10 11 11 11 12 12 13 13 13 13 14 14

HouseRep x 3 5 6 6 6 8 9 10 10 10 10 11 11 11 12 13 13 13 13 14 14 14 14 16 17 17 17 18 18

0 1 2 0 0 1 2 1 0 0 1 2 3 0 1 2 1 0 1 2 3 0 1 2 3 0 0 1 2 0 1

Code

:: 94 115 111 106 102 78 62

Sunlight analysis Y BSR X

2442 2442 2442 2572 2452 2452 2452 2572 2452 2452 2452 2452 2452 2442 2442 2442 2451 2452 2452 2452 2462 2452 2442 2442 2442 2671 2452 2452 452 2442 2442

80 43 76 47 71 51 49 762 78 43 82 39 86 35 48 982 50 1041 74 82 70 78 66 74 70 62 108 74 104 78 103 82 91 87 107 113 103 109 99 104 95 100 80 123 127 84 89 131 93 135 77 112 89 1211 93 125 98 130 63 125 59 129

Fig. 5. Program

10 10 10 07 07 07 33 09 20 11 11 11 12 13 18 18 22 18 18 18 18 07 07 07 07 69 20 18 09 09 09

Shops 391 400 409 413 413 415 361 365 362 363 371 322 373 382 296 287 420 420 420 420 402 433 433 437 437 200 268 283 283 419 427

Accessibility analysis School P.T. 275 203 292 295 296 299 265 249 246 246 235 365 257 265 278 270 304 304 304 304 286 317 317 321 321 143 152 265 265 303 311

4 0 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1

411 426 420 433 433 436 381 386 382 383 362 442 394 402 415 407 441 441 441 441 423 454 454 458 458 280 289 402 402 439 448

7 7 7 7 7 7 4 4 4 4 4 7 4 7 7 7 7 7 7 7 7 7 7 7 7 2 2 7 7 7 7

House Rep

PP 10 11 10 11 10 11 5 6 10 16 10 16 10 8 10 9 5 8 9 10 10 9 9 10 10 8 10 14 10 33 10 33 1 10 10 17 10 17 10 17 10 17 10 17 10 17 10 17 10 17 10 17 516 1 13 6 10 10 37 10 20

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

P.O.S.

0 1 2 0 0 0 1 0 1 1 1 0 1 3 0 0 1 2 2 1 0 0 1 2 2 0 0 2 2 0 1

35 35 35 1 48 48 10 2 3 32 32 32 29 27 50 50 15 19 19 19 19 46 46 46 46 5 3 19 37 37 39

1 2 3 4 4 5 6 6 7 9 10 10 10 10 11 11 12 12 13 13 13 13 14 15

0 0 2 0 1 0 0 2 0 0 0 1 2 3 0 1 0 1 0 1 2 3 3 0

202 201 300 304 301 306 373 378 374 375 384 434 386 394 407 399 311 311 311 311 293 324 324 328 328 272 281 394 394 310 310

Code 2442 2442 2442 2451 2451 2572 2452 2452 2671 2452 2452 2452 2452 2452 2442 2442 2451 2451 2452 2452 2452 2452 2442 2451

0 0 0 0 0 0 0 0 0 0 0 2 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Social

Health

359 368 377 301 381 304 329 334 330 331 340 291 342 350 264 256 389 389 389 389 371 402 402 406 405 228 237 251 251 387 396

278 287 295 360 360 303 370 374 371 372 388 430 362 391 404 395 308 398 384 368 289 321 321 325 325 268 277 391 391 306 3160

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0

Privacyanalysis D X Y 80 77 58 59 47 43 38 21 23 45 80 71 63 54 104 95 91 79 113 104 96 87 144 71

24 31 55 53 66 69 72 89 89 109 77 60 60 51 69 78 87 100 107 99 90 82 110 107

Site

0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

DPP

D

DPP

35 0 0 0 35 0 37 0 710 0 0 210 310 3 10 2 10 32 0 32 0 29 0 29 0 810 010 6 10 610 10 5 10 5 5 10 15 10 410 710

1 0 3 5 3 3 5 9 11 24 2 2 4 3 7 0 11 0 11 21 15 6 0 0

10 3 7 5 7 7 5 8 0 0 10 10 7 7 1 0 0 0 0 0 0 3 0 0

output,computer hardcopv prints: analystsofthe environmentalvariables. accessibility. p;ivacy and sunlight.

235 71 0 0 4 0 8

0 1 2 3 4 5 6 7 8 9 10

0 0 0

Pers.

PP

0

75.8 22.9 0 0 1.3 0 0 0 8

70.0 98.7 98.7 93.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0

Shops % Cum. %

0 1 2 3 4 5 6 7 8 9 10

PP

310 0 0 0 0 0 0 0 0 0 0

100.0 0 0 0 0 0 0 0 0 0 0

39.5 46.5 48.4 51 .l 51.1 55.7 55.7 55.7 55.7 56.8 100.0 _ __~~~~

%

0 0 26.2 0 36.8 0 0 38.1 0 0 0

293 0 17 0 0 0 0 0 0 0 0

94.5 0 5.5 0 0 0 0 0 0 0 0

P.O.S. 288 22 8 8 0 0 0 0 0 0 0

85.2 85.2 85.2 86.0 86.8 90.6 90.6 94.5 94.5 94.5 100.0

Cum. %

Accessibility

94.5 94.5 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

Houses PP Pers. Yo ______.__~~~~~ ~.. 0 264 85.2 0 0 : 0 0 3 5 1.6 4 0 0 5 12 3.9 6 0 0 7 12 3.9 8 0 0 9 0 0 10 17 5.5

0 0 25.2 25.2 61.9 61.9 61.9 108.0 100.0 100.0 100.0

P.T. % Cum.%

indicator

125 4 0 13 0 24 0 78 0 0 66

Roads

92.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

Pers.

indicator

92.9 7.1 0 0 0 0 0 0 0 0 0

Social

_._~ Health 94.5 100.0 100.0 100.0 too.0 100.0 100.0 too.0 100.0 100.0 100.0

40.3 41.6 41.6 45.8 45.8 53.5 53.5 78.7 78.7 78.7 100.0

Cum. %

94.5 5.5 0 0 0 0 0 0 0 0 0

points and

40.3 1.3 0 4.2 0 7.7 0 25.2 0 0 21.3

%

293 17 0 0 0 0 0 0 0 0 0

Fig. 6. Program output, computer hardcopy prints; environmental indicators showing penalty cumulative percentages of population atl’ected by the environmental deficiencies.

39.5 7.0 1.9 2.7 0 4.6 0 0 : 0 4 1.1 160 43.2 ~~~~ _~ ~___~

146 26 7 10 0 17 0

0 0 70 8 114 0 0 118 0 0 0

Pers.

indicator % Cum.

100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

School % Cum. 96

Sunlight Pers.

Pers.

Accessibility

0 0 0

0 0 0

0 0 0

0 0 0

Site 100.0 0 0 0 0

310 0 0 0 0

100 100 100

100 100 100

100 100 100 100 100

; 6

3 < z

g I= z. z

s

2 E?. E c. g

E

2 ? E.

2 3 ‘D

CAHID AYBET

210

I

1

Penalty

pomts for enwronmentol deflclencles

Fig. 7. Computer hardcopy print of summary graph showing percentages of population affected in relation to penalty points given to deficiencies in three environmental variables.

scheme. This enables the user (designer or decision-maker) to select the most suitable layout to the particular type and purpose of the development. The layout appraisal program is therefore intended to be used as: (i) an optimization tool during the design process, and (ii) an evaluation tool in the decision-making process. The environmental indicators developed and used in the program describe and measure various physical characteristics of the spatial structure of a residential environment. The factors considered in each environmental indicator represent the benefits which residents will enjoy or the environmental deficiencies which residents will suffer from. These indicators are weighted against the development variables-space allocation, distribution of dwelling types and development costs-; penalty scores are cumulative which indicate the total detrimental effect of the environment with regard to a particular environmental variable. They illustrate how well the physical environment performs some of its functions and responds to the operational demands of people. As the environmental variables are related to the development variables, the evaluation process illustrates the interactions between the environmental quality to be gained, spatial form of the development and the cost of providing it. The program, thus, indicates the likely consequences of designed housing layout forms in environmental terms. REFERENCES for Housing. National Building Society, London (1971). 1. Buchanan C. & Partners. Prospects 2. Maver T. W. The computer as an aid to architectural design: present and future. Progress in Construction Science and Technology, M.T.P. 3. Peterson G. L. Quantitative analysis of the perception of the visual appearance of neighbourhoods. J. Reg. Sci. 7, 19-3 I ( 1965). 4. Craik K. H. Comprehension of the everyday physical environment. J. Am. Inst. Plum 34 (January 1968). 5. Wailer R. A. ‘Environmental quality’ measurement and control. Reg. Stud. 4(2) (1970). 6. Department of the Environment. Estate Outside rhe Dwelling. H.M.S.O., London (1972).