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Unit 1 Introduction to Mechanical and Electrical Building Systems

1.1 Introduction There was a time, when buildings were simply protection against the elements, to keep out the rain and the cold and to house people and simple machinery. However, in the last few decades, this has changed radically. As the complexity of our equipment grows, we need structures that adapt to our fluctuating needs in temperature, lighting, and humidity. As well, our work places must consider our comfort and communication capability. And, as the human footprint on the world increases, so must the designer of building systems provide high air quality and superior water and sanitation systems. Continual improvement in our private and working lives is the challenge of those involved in building services.

Fig 1-1 Integrated building systems

1.2 Who designs Building Systems? Mechanical and Electrical Systems (M/E) for buildings are traditionally designed by specialized consultants. At one time architects used to design such systems. But now the systems are much more complex and beyond the scope of the architect. Consultants are hired by the client to design, draw, and supervise the electrical, mechanical, and industrial systems that are incorporated into residential, commercial, and industrial buildings. Practically any building or structure being built or renovated requires the services of an M/E consultant. And because of energy conservation, there are now companies that specialize in design and implementation of energy conservation systems in new and older buildings.


Relation of the Architect to the Job Whenever the construction of a new building is contemplated, an architectural firm is usually commissioned to prepare complete working drawings and specifications for the building. These construction documents usually include the architectural drawings which show the design and building construction details-the floor plan layouts, vertical elevations of all building exteriors, various cross sections of the building, and other details of construction. While the number of drawings will vary depending on the size and complexity of the job, the drawings will almost always fall into the following five general groups:

• Site Work - The site or plot plan usually will include the location of the building on the property as well as the outside utilities which will serve the building.

• Architectural - The architectural drawings usually will include: elevations of all

exterior faces of the building; floor plans showing walls and partitions for each floor; and sufficient cross sections to indicate clearly the various floor levels and details of the foundation, walls, floors, ceilings, and roof construction. Large-scale detail drawings may also be included.

• Structural - Structural drawings are usually included for long-span wood-truss

construction, and all drawings of reinforced-concrete and structural steel construction are prepared by structural consulting engineers.

• Electrical - The electrical drawings will cover the complete design and layout of

electrical wiring systems for light, power, and communication.

• Mechanical - The mechanical drawings

will cover the complete design and layout of the plumbing, piping, heating, ventilating, and air-conditioning systems and related mechanical construction. Electrical-control wiring diagrams for the heating and cooling systems are very often included on the mechanical drawings also.

Relation of the Consulting Engineer to the Job When electrical and mechanical systems in buildings became more extensive and complex, architects began hiring consulting engineers to design and layout these systems. The consulting engineer usually will act as liaison between the architect and the electrical and mechanical contractors; the consulting engineer will handle the details of the electrical and mechanical construction from the time the design and layout of the work is started, through the bidding and construction sequences; to the final approval and acceptance of the finished job.


Although consulting firms vary in both size and types of services offered, most have an electrical, a plumbing, and a heating, ventilating, and air-conditioning design department.

The Building Systems Technologist The designer (engineer/technologist) will use the architect's drawings as a reference when designing a suitable building system for the building in question. This involves calculating various flow rates and other criteria to meet the requirements of the occupants. Usually the designer's layout is then roughly sketched and, in turn, is given to the draftsperson (technician/technologist) to complete. The draftsperson's responsibility is to provide drawings of the design which are neat, detailed, and accurate and which will indicate, beyond any question of a doubt, exactly what is required to install a correct system in the building. M/E consultants hire BSET graduates to design and draw systems as well as review and supervise implementation of such systems. After practical experience is gained, the BSET graduate often enters a project manager's role, overseeing projects or design teams.

What does the Building Systems student learn? The BSET student learns to design and draw his/her own commercial building by initially learning architectural and structural practices. This gives a better understanding of the building envelop. The student then designs the electrical systems such as power and lighting. The water services are calculated and drawn as well as the heating, ventilation, and air conditioning. By the end of the second year, the student has a portfolio that displays his or her skills in computer aided drafting and design. Not only can the graduate draw the systems but can design them as well. BSET graduates find employment in a variety of disciplines - Consulting firms (mechanical, electrical, plumbing, industrial or environmental), Architectural firms, and Structural Design and Detailing firms. This is because their varied skills make them more adaptable and, therefore, more employable. BSET graduates often find themselves training fellow employees in the use of advanced CAD techniques because of their extensive training.

Fig 1-2 Student’s rendered and animated 3D Model


1.3 The Scope of Building M/E Systems The complexity of M/E systems varies with the living standards of the society, climatic conditions of the region, and occupancy and quality of the building. For example, a house located in a mild climate may not require either heating or cooling, regardless of the quality of the house; a warehouse for bulk storage may not require any heating, even in a freezing climate; a modern hospital must have a supply of medical gas, standby electrical power, and telecommunications systems to meet present health care standards; and a small office building may appropriately have window-type air conditioners, whereas an intelligent high-rise office building would most likely be designed with a central HVAC system complete with computer-based building automation and management controls. Building M/E systems may be classified into three major categories:

Mechanical Systems • HVAC Heating, ventilating, and air conditioning • Site utilities Water supply, storm water drainage, sanitary disposal, gas supply • Plumbing Water distribution, water treatment, sanitary facilities, etc. • Fire protection Water supply, fire and smoke detection, automatic sprinklers, etc. • Special systems

Electrical Systems • Electrical power Normal, standby, and emergency power supply and distribution • Lighting Interior, exterior, and emergency lighting • Auxiliary Telephone, signal, data, audio/video, sound, fire alarm, security systems,

etc. • Special systems

Building Operation Systems • Transportation Elevators, escalators, moving walkways, etc. • Processing Production, food service, etc. • Automation Environmental controls, management, etc. • Special systems

Fig 1-2 Mechanical, Electrical, Building Operation


1.4 A Holistic* Design Philosophy With the continued deterioration of our environment and consumption of our limited natural resources, we have pushed the environment to the threshold at which design alternatives must be seriously considered and pursued. There is a trend to move design policy so that it includes the important aspects of the 'whole buildings' approach to design and construction. The goal is to create buildings that are responsive, responsible, and defensible. Toward that end, buildings must be competently planned; functionally adequate; appropriate in form; cost- effective; constructible; adaptable, durable, and contextual. 'Whole buildings' design not only looks at how materials, systems and products of a building connect and overlap but also looks at how the building and its systems can be integrated with supporting systems on its site and in its community. A successful 'whole buildings' design is a solution that is greater than the sum of its parts. The fundamental challenge of 'whole buildings' design is to understand that all building systems are interdependent. Through a systematic analysis of these interdependencies, a much more efficient and cost-effective building can be produced. The choice of a mechanical system, might, for example, impact the quality of the air in the building, the ease of maintenance, Global Climate Change, operating costs, fuel choice, and whether the windows of a building are operable. In turn, the size of the mechanical system will depend on factors such as, the type of lighting used, how much natural daylight is brought in, how the space is organized, the facility's operating hours, and the local microclimate. Refer to Figure 1-2.

Fig 1-2 Interfacing is necessary among the design disciplines to achieve a balanced solution as to optimum spatial relations, aesthetics, environmental quality, acoustics, energy efficiency, and cost-effectiveness.

* Relating to an analysis of the whole instead of a separation into parts


1.5 The Impact on Design The floor area necessary tor M/E system in a building varies widely, depending on the occupancy, climatic conditions, living standards, and quality and general architectural design of the building. The M/E space affects the gross floor area, footprint (the size and shape of the building's ground floor), floor-to-floor height, geometry, and architectural expression. Reasonable allocations made during the space programming phase allow M/E space to be appropriately sized and strategically located. Space planning tor M/E systems is one of the most challenging and least developed procedures in the architectural design process.

Fig 1-3 Mechanical Systems in Buildings

Floor Area Prior to the development of reliable and affordable M/E systems, buildings designed tor human occupancy followed a simple rule: every room must have exterior operable windows for the introduction of daylight and for natural ventilation. Accordingly, most buildings are L-, U-, or H-shaped, having either single- or double-loaded corridors. It is not difficult to conclude that buildings of the designs shown in the figure have more exterior wall surface area than the deep block-type design and thus have more heat gain or loss, as well as a higher construction cost.


Theoretically, a building is most efficient if 100 percent of the interior space can be utilized tor occupancy. This is possible tor a small, single-story building with all major M/E equipment located on the roof or at the exteriors. Multistory buildings gradually lose space utilization efficiency, owing to their need tor stairways, elevators, and M/E equipment space.

Floor-to-Ceiling Height It can be shown that any building with height greater than half its base dimension is less energy-efficient and more costly to build than one with height less than or equal to half its base dimension. High-rise buildings arc in this category, and the taller the building, the less the energy efficiency. While no building will be built simply to achieve a better Volume to Surface Ratio, this criterion should not be overlooked in considering alternative designs of a comparable-size building.

1. Walls and columns 2. Lighting 3. Ventilation 4. Cable Trays 5. Fire Protection 6. Power and data 7. Suspended Ceiling

Fig 1-4 Utilization of Ceiling Space

Architectural Style The major influence of M/E systems on modern architecture has been not only in building height, but in architectural style, facade, form, and expression. Architectural and structural system interfacing has long been established in the history of architecture. In the past a building’s structure and mechanical systems were hidden. But with more current designs the structural members and mechanicals systems are exposed and part of the architectural design.


Construction Costs The impact of M/E systems on construction cost varies greatly, depending on the type of building, standard of living of the country, architectural design, and M/E systems selected. The range of M/E systems costs tor fully air-conditioned and high-quality buildings can be as little as 10% to as high as 60%. These values may serve as a general reference from which to modify and to refine the costs throughout the design process.

Operating Costs The operating cost of a building includes the cost of routine maintenance, repairs, replacements, and utilities. Most architectural and structural components or a building (except the roof) are normally long-lasting, without the need for frequent replacement. This is not the case, however, tor most M/E systems, which not only consume energy but also require ongoing maintenance and repair. Indeed, over a life cycle, the cost of owning and operating M/E systems may outweigh the initial capital investment of the entire building! Naturally, the importance of efficient M/E systems and management cannot be overemphasized.

Energy Conscious The American Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc. (ASHRAE), and the Illuminating Engineering Society of North America (IESNA) have jointly developed energy-efficient design standards known as Standard 90, published in 1975, revised in 1980, and again revised in 1996. These standards have been widely adopted as part of the building codes in the United States as well as in a number of other countries. The standards provide three alternative methods of achieving compliance: a prescriptive method, a system performance method, and a building energy cost budget method. The standards are available to design professionals and building owners as a guide to energy-efficient design in new and existing buildings. Building owners and designers should strive to meet or exceed these standards.

Fig 1-5 Light Tubes


1.6 Check List of Building and M/E Requirements This section presents a comprehensive checklist which serves to determine the scope of building operational requirements and from which one can determine the scope and criteria of M/E systems. The checklist also will be valuable in formulating the architectural con-cept, building configuration, space programming, and opportunities of system interfacing. Early identification of these requirements will aid the architect in evaluating construction costs, as well as in allocating space tor M/E equipment, both within and outside the building. The checklist is divided into two parts: mechanical systems and electrical systems. Refer to tables 1-7 and 1-8 later on in this section.
