Sand and dust

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In many dry areas sand and dust may cause considerable discomfort, eye irritation, problems with food preparation, increased wear of machinery and even damage to buildings due to erosion. Sand is carried by the wind and can be stopped by hedges, screen fences or similar semiopen structures that reduce wind velocity and cause the sand to come to rest. Dust is more difficult to stop, but tightly closing shutters will give a large measure of protection as will vegetation around buildings.

Building shapes which create pockets or surfaces on which sand and dust may accumulate should be avoided since the added weight may conceivably cause structural failure.


In areas where earthquakes occur frequently buildings must be designed to resist the stresses caused by the tremors. While the intensity of tremors can be much greater in loosely compacted soil than in firm soil or solid bedrock, one- and two-story buildings are at greater risk on the firm ground or bedrock because of the shorter resonance periods.

Casualties are most likely to be caused by the collapse of walls causing the roof to fall, and the failure of projecting elements such as parapets, watertanks, nonmonolithic chimneys and loose roof coverings. The outbreak of fire caused by the fracture of a chimney or a break in the mains supply line presents an additional hazard.

While small buildings, having timber frame walls or a wooden ring beam supported by the posts of a mudandpole wall, can resist quite violent earthquakes, the following measures will increase the resistance of a large building to collapse due to earth tremors:

Ductile structures have many joints that can move slightly without failing, e.g., bolted trusses. Such structures have a greater capacity to absorb the energy of earthquake waves. A symmetrical, uniformly distributed ductile framework and with the walls securely fixed to the frame, is suitable for large buildings.

Masonry walls are sensitive to earthquake loads and tend to crack through the joints. It is therefore important to use a good mortar and occasionally reinforcing will be required.

Further reading

American Society of Heating, Refrigeration and Airconditioning Engineers, ASHRAE Handbook of Fundamentals, New York, 1980.

Building Research Establishment, Overseas Division, Building in Earthquake Areas, Overseas Building Notes No. 143, Garston, Watford, Building Research Establishment, 1972.

Burberry P., Environment and Services, Mitchell's Building Series, London, B. T. Batsford Ltd., 1979.

East African Meteorological Department, Climatological Statistics for East Africa, Nairobi, East African Community, 1975.

Geiger R., The Climate Near the Ground, Cambridge, Mass., Harvard University Press, 1966.

Givoni B., Man, Climate and Architecture, Barking, Essex, Applied Science Publishers, Second Edition, 1976.

Griffiths J. F., Applied Climatology, An Introduction, Oxford, Oxford University Press, Second Edition, 1976.

Harkness E. L., Mehta M. L., Solar Radiation Control in Buildings, Barking, Essex, Applied Science Publishers, 1978.

Hooper C., Design for Climate. Guidelines for the Design of Low-Cost Houses for the Climates of Kenya, Nairobi, Housing Research and Development Unit - University of Nairobi, 1975.

Hydrological Survey Department, Meteorological Data, Maseru, Ministry of Works and Communications, 1971.

Koenigsberger O. H., Ingersoll T. G., Mayhew A., Szokolay S. V., Manual of Tropical Housing and Building, Part 1: Climatic Design, London, Longman Group Ltd., 1973.

Koenigsberger O. H., Lynn R., Roofs in the Warm Humid Tropics, Architectural Association Paper No. 1, London, Lund Humphries, 1965.

Konya A., Design Primer for Hot Climates, London, Architectural Press Ltd., 1980.

Mather J. R., Climatology. Fundamentals and Applications, New York, McGraw-Hill, 1974.

Meteorological Department, Climatological Summaries for Zambia. Lusaka, Meteorological Department, 1971.

Oakley D., Tropical Houses: A Guide to their Design, London, B. T. Batsford Ltd., 1961.

Olgyay V., Design with Climate, Bioclimatic Approach to Architectural Regionalism, Princeton NJ, Princeton University Press, 1963.

Olgyay V., Olgyay A., Solar Control and Shading Devices, Princeton, NJ, Princeton University Press, 1976.

Redding G. J., Functional Design Handbook for Australian Farm Buildings, Melbourne, Agricultural Engineering Section, University of Melbourne, 1981.

United Nations, Department of Economic and Social Affairs, Low-cost Construction Resistant to Earthquake and Hurricanes, New York, United Nations, 1975.

Van Straaten J. F., Thermal Performance of Buildings, Amsterdam, Elsevier, 1967.

Whitaker J. H., Agricultural Buildings and Structures, Reston, Va., Reston Publishing Co., 1979.

Chapter 8 Functional planning

The majority of African farmers are small-holders who have limited resources and income and thus a low standard of living. The primary goal for most of these farmers is to produce food for the family together with some marketable surplus that can provide the income for such things as children's education and goods for personal consumption. However, as urban populations increase, the demand for commercial crop production is turning many farmers to the goal of financial profit in operating their farm businesses. In any case, the farmer will want to make optimum use of his resources (land, labour, capital and fixed asset ), in order to achieve the desired results.

Functional planning is essential if this goal is to be realised. A good plan should provide an understanding of the situation and how it can be changed and thus assist the farmer to see his problems, to analyse them and to enable him to make soundly based decisions when choosing between alternative uses of his resources.

While farm management planning helps the farmer to choose the type and quantity of commodities to produce, the advice from crop and livestock production specialists is required to help him decide how to produce it in an efficient way. When an enterprise requires buildings or other structures, the farm building specialist will suggest alternative designs for efficient use of resources. The best plan for the whole farm operation will result from the various disciplines of farm planning being considered together.

The great number of small farms in most developing countries makes it impracticable to devise a plan for each farm. Instead, a few case studies that are representative of farms in the target population should be analysed to produce guidelines that can be promoted among the farmers in the region by the extension service.

Similarly, the farm building engineer can produce standard designs that are directly, or with small modifications, suitable for a large number of farms in an area. However, the number of case studies and designs must be sufficient to allow any farmer to be given advice that reflects his situation and which he is likely to adopt.

When plans are executed and resources invested in a farm enterprise, the resources will be tied up and unavailable for alternative plans for some period of time. Since buildings are fixed assets that have a relatively long life span and consume a relatively large amount of resources for their construction, it is of special importance that they be planned for efficient and profitable use throughout their life. Planning done on paper is an inexpensive way and analyse alternatives and discuss the possibilities for satisfying the objectives as established by the farmer. Once a building is erected, however, it is expensive to make changes.

Rural planning

Clearly, a plan for an individual farm is influenced by a number of factors over which the farmer has no direct control e.g. as climate, soil fertility, government policies, state of knowledge about agricultural techniques, and value of inputs and outputs. However, since many african smallholders produce mainly for the farm household, they are only slightly affected by changes in policy and prices.

Nevertheless, national and regional rural development plans should be considered as they may provide the basis for plans for a community of farmers or an individual farm. Rural planning is carried out in the national interest to improve living conditions, balance agricultural production to demand and conserve natural resources. Many factors in the national or regional plans may directly influence the choice of production at a farm and thus the requirement of buildings.

The aims of the planning strategies in rural areas are based on political decisions. They can include:

An improved road network may, for example, make new urban markets accessible, thus making it feasible for the farmers to go into vegetable or milk production. This in turn may require housing for animals, stores for produce and feed . It would therefore be wise to investigate any plans for rural development in an area during the planning stages at an individual farm or an extension campaign promoting improved building designs in that area. Government policy is often an important factor in determining the long term market trends and thus profitability of market production, and is therefore of special importance when planning for production operations involving buildings.

Economic planning of the farm operation

Most textbooks on agricultural economics describe methods of economic planning for commercial farms in developed western countries, but very few deal with methods relevant to the African small-holders. Although the principles of economic theory may be relevant when reviewing African small-scale farms, their applications will undoubtedly differ from those used when reviewing commercial farms. Traditional applications assume, for example, that crop and livestock can be analysed separately, that the concept of farm size can be unequivocably defined, that the farmer makes all the decisions concerning farm operations, and that increasing cash income is the major objective. However, African agriculture is traditionally based on communal landownership and many include a multifamily situation in which two or more wives each have their own plots, but also participate in joint enterprises and are subordinate to the husband's general decisions. This situation would make an approach to local community groups more relevant than to emphasize individual farms. A multiple cropping system or a livestockfeedcrop system may serve to reduce risk and result in a more uniform supply of food and cash as well as family labour demand and, although the yields of the individual enterprises may be low, provide an acceptable overall result.

Money is the commonly used medium of exchange in economic calculation and often the most convenient. However, other units may occasionally be more relevant when small farms, having limited cash flow and strong nonmoney relations between production operations and household, are analysed. A subsistence farmer may, for example, value the security of having his own maize production so much that he will produce enough for the household even if an alternative enterprise using the land and labour would generate more than enough cash to buy the maize at the market. The principles of economic theory are valid whatever appropriate medium of exchange is used to specify the quantities, e.g. units of labour used to produce units of grain, meat etc. The difficulty is to find a suitable alternative unit to use where the gains and losses are a mixture of money and non-money elements and to take into consideration the farmer's personal beliefs so that the resulting plan reflects his goals and value system.

The initiation of a building production process (see Chapter 6) is often a reason to review the economic planning for the entire farming operation. The plan will establish the resources available and the limitations and restrictions that apply to the construction of a proposed building. A comprehensive economic plan for a farm, whether an actual farm or a case study farm, may include the following steps:

1 Establishment of the objectives, priorities and constraints the farmer has for his farm operation. The objectives should preferably be quantified so that it can be determined whether they are being or can be achieved.

2 Analysis of financial resources, i.e. the farmer's assets as well as the cost and possibility of obtaining loans.

3 Listing of all available resources for the farming enterprises, quantifying them and describing their qualities, e.g. quantity and quality of land water resources, tools and machines, roster of labour including a description of training and skills, existing buildings and evaluation of their serviceability, the farmer's management skills, etc.

4 Description of all factors in the physical, economic and administrative environment which directly influence the farming enterprises but over which the farmer has no direct influence, e.g. laws and regulations, rural infrastructure, market for produce, availability of supplies, prices and market trends etc.

5 Individual analysis of each type of farm enterprise, whether crop or animal production, to determine its allowance of total capital. Note that where multiple cropping is practiced, the mix of various crops grown together is considered to be one enterprise.

6 Determining the optimum mix of enterprises that satisfies the farmer's objectives and makes the best use of resources.

The resulting plan will be an expression of the farmer's intentions for the future development of the family farm. The plan will contain several interrelated sub-plans as shown in Figure 8.1.

Figure 8.1 Schedule of a sub-plan in a farming enterprise.

Note that the sub-plans in Figure 8.1 may interplay in many more ways than have been illustrated. Many of these inter-relationships are of great importance when trying to maximize the result of the total production at the farm, whether the product is sold or not. Optimization of each individual enterprise may not necessarily mean that the total farming enterprise is optimized.

Where one is satisfied that the farmer already operate his farm according to a sound economic plan, a less ambitious approach, involving analysis of only the enterprise requiring a new or remodeled building and an investment appraisal, may suffice. A number of investment appraisal methods have been advocated for use in agriculture to give a rough indication of the merits of an investment. However, small-holders generally heritate to risk cash for investment in fertilizer, pesticides and feed concentrate as well as improved buildings and machinery until enough food for the household is produced, a market with a cash economy is readily available and the farmer is confident in his own technical, agricultural and economic skills. Money therefore, may not always be the most relevant unit to use in the calculations.

An approach to building planning

Once the building requirements have been established in the economic planning, it will be the task of the farm building engineer to work out the functional and structural designs and deal with the farmstead plan.

The planning process always starts with a list of available resources and restrictions and other bac kground material. The major outline for the design is then sketched. The final design is developed by working from rough sketches towards more and more detailed plans of the different parts of the building. Often however, when some internal units such as a farrowing pen has been designed and the number required established, the dimensions of the final building will be influenced by the pen size and number. The farmer will often impose restrictions on the design before the planning process begins. these should be critically evaluated and their effectiveness examined before they are accepted as part of the final design. it will be useful to discuss the extent of the proposed building and enterprise with an agricultural economist if the plan has not been based on an overall economic plan.

Standard solutions, published by demonstration structures and extension campaigns will, for some time future be the most important means of introducing improved building designs to small-scale farmers. However, the improved standard designs will be widely accepted by farmers, only if they are based on thorough understanding of the agricultural practices and human value systems prevalent in the local farming community and are developed to utilize locally available building materials and skills. New ideas, materials and construction methods should be developed and introduced to complement the strengths of the indigenous methods. Local builders, will be valuable sources of information regarding indigenous building methods and effective channels through which innovations, can be introduced. Close cooperation between builders and farmers will help the local community to deal with its own problems and to evolve solutions from indigenous methods and local resources which will have good prospects of getting accepted.

Background Information

An economic plan for the farming operation, will provide much of the bac kground information required by the farm building engineer. As this is often missing, such information will have to be obtained by interviewing farmers and by studying similar farms in the area. Where the design is developed for a specific farm, priority should be given to gathering as much information as possible from that farm. All information should be critically evaluated prior to its acceptance as bac kground material for the design of the proposed building or for a standard drawing.

In the previous section a number of factors that should be considered in developing an economic plan are listed. The farm building engineer should obtain as much of that information as possible, in addition to data relating to the following factors:


The standardized economic calculations used to determine the gross margin in a farm operation are often limited in scope and therefore a more detailed examination of the enterprise housed in the building may be of use. Knowing the expected production volume, additional data is calculated using the bac kground information.

In the case of a storage building, the expected volume of crop to be stored as well as the required handling capacity is determined. In a multi-purpose store where several different commodities are held, a schedule of the volumes and storage periods will be useful to determine the maximum storage requirement.

Analysing the Activities

Activity analysis is a tool used in planning the production in large, complex plants such as factories, large-scale grain stores and animal production buildings, but it can also be a useful instrument in smaller projects, particularly for the inexperienced farm building engineer.

Figure 8.2 Diagram for the lay-out planning procedure.

Most production operations can be carried out in several ways involving various degrees of mechanization. By listing all conceivable methods in a comparable way, the most feasible method from a technical and economical point of view can be chosen. This will ensure good care of produce and animals and effective use of labour and machines. Uniformity in the handling improves efficiency, e.g. produce delivered in bags to a store should be kept in bags within the store, particularly if it is to be delivered from the store in bags.

In animal housing projects, the handling operations for feed, animals, animal produce and manure are similarly analysed. Note that the analysis of handling operations for feed produced at the farm should include harvesting and transport from the field since these operations may determine the most appropriate storage and handling methods inside the building.

Figure 8.3 Example of a material flow diagram for a dairy unit.

When all handling operations have been analysed the result is summarized in a schedule of activities.

Labour efficiency is often an essential factor in small farm development. If a farmer has a reasonable standard of living, cultural norms and social pressures may limit his willingness to invest his labour for a relatively low return, while labour efficient methods allowing for a reasonable return on the labour invested, may increase his willingness to produce a surplus.

Room Schedule

This is a brief description of all rooms and spaces required for work, storage, communication, service of technical installations, etc. Because variation in yield and other production factors are to be expected, an allowance is added to the spaces and the volumes. It would not be uneconomical however, to allow for the most extreme variations, particularly if a commodity to be stored is readily marketable and can be bought back at a reasonable price later.

The total space requirement is then totaled. Also, partial sums indicate how the production operations can be divided into several houses.

Communication Schedule

This describes the requirement and frequency of communication between the various rooms and spaces within the building and between the building and other structures at the farmstead. A schedule for movements between farmstead and the fields and the market is also essential. It may also include quantities to be transported. Based on this information rooms having frequent communication can be placed close together for convenience and work efficiency when the building is being designed. The communications schedule is not always accounted for separately, but instead may be included in the schedule of activities.

Following the principle of working from the major outline of the project towards the details, the next step is to place the proposed building on the farmstead. Some factors under farmstead planning will be discussed in section Farmstead Planning. Efficient communication within the farmstead is of great importance in creating a functional and harmonious operation. The schedule of functions serves as a checklist when transport is analysed. The room schedule provides information on the size of the buildings and the structural concept likely to be used.

A standard design can obviously not be shaped to fit at a specific farmstead. Nevertheless may the group of farms that the design is developed for have common features, which allow the designer to make recommendations concerning the placing of the new building. Some structures have special requirement as to where at the farmstead they be constructed. A maize drying crib must for example be exposed to wind.

Where the plan includes the addition of a new building to an existing farmstead, alternative locations for the proposed building are sketched on the master plan or, better still on transparent paper covering the master plan, and the communication routes are indicated by arrows between the buildings, the fields and the access road.

Considering all the planning factors and requirements, one location of the proposed building is likely to have more advantages and fewer disadvantages than other alternatives. The transport routes to and from the building are then further studied and noted for use when the interior of the building is planned.

The farmer will often have a firm opinion about the placing of the building from the start of the planning process. His opinion should be critically examined, but naturally it should be given considerable weight when the site is finally chosen.

Functional Design of the Building

The sketching of alternative plan views of the building is mainly a task of combining and coordinating the requirements that have been analysed in earlier steps. Some general guidelines are as follows:

Finalization of Sketching

After a number of sketches have been produced they are carefully analysed to select the one that best reflect the farmer's objectives. However, because a farmer's objectives are usually complex and difficult to elicit, it is common to use more readily evaluated criterious such as total construction cost or cash expenditure. The selected building plan is then drawn in its correct size, sections and elevations are sketched and, where applicable, the building is positioned on the master plan. Frequently, the result of earlier steps in the planning process such as activity schedule or room schedule will have to be reviewed and adjusted as the work progresses.

Prior to being widely promoted, standard designs are often tested at a few typical farms. The construction phase and a period of use will often give rise to useful experiences that may result in improvements of the design. Only if the designer is continuously prepared to modify the design as needed to adapt it to changing agricultural practices will it have a good chance of being successful in the long run.

A 'one of its kind design' intended for a specific farm can obviously not be tested in practice prior to its construction. Therefore the sketch including a cost estimate, must be presented and carefully explained to the farmer so that he understands them and feels confident that he can run an efficient and profitable production in the building. Not withstanding this, the farmer is likely to have objections and suggestions for alterations, which must be considered and worked into the final sketches. Because an understanding of the operation and a positive attitude by all concerned are basic requirements for efficient production, farm labourers and members of the farmer's family who will be working in the building, should also be given an opportunity to review the sketches.

Final Design

When all sketches (farmstead plan, functional plan and structural concept) have been corrected, coordinated and approved by the farmer, the final building documents as described in Chapter 1 are prepared.

Farmstead planning

The farmstead forms the nucleus of the farm operation where a wide range of farming activities take place. It normally includes the dwelling, animal shelters, storage structures, equipment shed, workshop and other structures. A carefully organised farmstead plan should provide an arrangement of buildings and facilities that allows adequate space for convenient and efficient operation of all activities, while at the same time protecting the environment from such undersirable effects as odours, dust, noise, Dies and heavy traffic. A wide range of factors, described in section Communication Schedule, should be considered when planning the arrangement of buildings and services at the farmstead.

Although the immediate objective of these plans may be the inclusion of a new building in an existing farmstead, provision should be made for future expansion and replacement of buildings. In this way a poorly laid out farmstead can be improved over the long term.

Zone Planning

Zone planning can be a useful tool, but it is most effective when planning a new farmstead. The farmstead is divided into zones 10 to 30 metres wide by concentric circles as shown in Figure. 8.4.

Figure 8.4 Zone planning in four zones.

Zone 1 at the centre of the farmstead is for family living, and should be protected from odour, dust, flies, etc. In Zone 2 clean, dry and quiet activities, such as implement sheds and small storage structures can be placed. In Zone 3 larger grain stores, feed stores and small animal units are placed, whereas large-scale animal production is in Zone 4 and beyond.

The advantage of zone planning is that it provides space for present farm operations, future expansion and a good living environment. However, in many African cultures the livestock has traditionally been placed at the centre of the farmstead. Thus the zone concept runs counter to tradition and may not be desirable.

Farmstead Planning Factors

Good drainage, both surface and sub-surface, provides a dry farm courtyard and a stable foundation for buildings. A gentle slope across the site facilitates drainage, but a pronounced slope may make it difficult to site larger structures without undertaking extensive earth-moving work. Adequate space should be provided to allow for maneuvering vehicles around the buildings and for future expansion of the farm operation.

Air movement is essential for cross ventilation, but excessive wind can damage buildings. Since wind will carry odours and noise, livestock buildings should be placed downwind from the family living area and neighbouring homes. Undesirable winds can be diverted and reduced by hedges and trees or fences with open construction. Solar radiation may adversely affect the environment within buildings. An orientation close to an east-west axis is generally recommended in the tropics.

An adequate supply of clean water is essential on any farm. When planning buildings for an expanded livestock production, the volume of the water supply must be assessed. Where applicable, the supply pipe in a good building layout will be as short as possible. Similarly, the length of electric, gas and telephone lines should be kept to a minimum.

The safety of people and animals from fire and accident hazards should be part of the planning considerations. Children especially, must be protected from the many dangers at a farmstead. It is often desirable to arrange for some privacy in the family living area by screening off the garden, outdoor meeting-resting places, verandah and play area.

Measures should be taken for security from theft and vandalism. This includes an arrangement of buildings so that the farm court and the access driveway can be observed at all times, especially from the house. A neat and attractive farmstead is desirable and much can be achieved toward this end, at low cost, if the appearance is considered in the planning, and effective landscaping is utilized.

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