An Architect's Guide for Sustainable Design of Office Buildings

2. Health and Well-Being

2.0 Introduction

If salaries are considered as part of building economics, the substantial value of providing environments that are positive and supportive of occupant health and productivity become immediately evident. According to a recent study commissioned by US National Energy Management Institute, improving indoor air quality (IAQ) in buildings could result in a payback in terms of productivity and decreases in medical costs in less than two years.^[1]

Concern over indoor air quality has become a public health issue through the past two decades as a result of the energy conservation measures in the 1970s which restricted ventilation rates, the increasing use of synthetic building, materials, the introduction of information technologies in offices without the benefit of adequate ventilation, and individuals typically spending between 80 to 90% of their time indoors.

By the early 1980s, research began to demonstrate the correlation between exposure to indoor air pollutants and health problems with symptoms ranging from eye irritation, headaches, and fatigue to respiratory diseases and cancer. These reactions to contaminants have led to the recognition of the notion of Sick Building Syndrome (SBS).

The perception of air quality can also be exacerbated by inappropriate thermal, lighting and acoustic conditions. The improvement of the indoor environment thus requires a multi-disciplinary and integrated approach. Architects, as team leaders, have a key role to play in ensuring at the outset of a project that design requirements will incorporate these important considerations.

Office building design objectives include:

• Providing comfortable and healthy work conditions which satisfy the maximum number of building occupants;
• Providing these conditions within an acceptable energy and cost framework;
• Ensuring that such conditions can be operationally maintained.

2.0.1 Environmental Standards

Occupational safety and health is regulated under Canada Labour Code, Part II, Occupational Safety and Health, 1996. Under this policy, government departments have the responsibility to ensure a safe and healthy workplace to occupants of buildings under federal jurisdiction, including the provision of environmental conditions in accordance with prescribed standards.

PWGSC environmental requirements for the design of new and renovated federal facilities are set in MD 15000, Environmental Standards for Office Accommodation,^[2] published in November 1994, which includes provisions related to ventilation, temperature, relative humidity, and acoustics. MD 15000 incorporates many requirements of ASHRAE Standard 55-1992, Thermal Environmental Conditions for Human Occupancy^[3] and Standard 22-1989, Ventilation for Acceptable Indoor Air Quality,^[4] which are generally accepted guidelines for ventilation and Indoor Air Quality (IAQ). The scope of these standards is limited to issues generally under the responsibility of HVAC design engineers.

Indoor air quality standards issues are dealt with more comprehensively in CSA Z 204-94, Guidelines for Managing Air Quality in Office Building, Occupational Health and Safety.^[5]

Recommendations for good lighting practice are set by the Illuminating Engineering Society of North America (IESNA)^[6] and PWGSC's Design Standard RPSB/DGSI 1-4:95-1, Office Lighting.^[7]

2.1 Improving Thermal Quality

Thermal quality can be defined as the absence of discomfort caused by temperature, humidity and air movement conditions that are inappropriate to the task at hand.

Though not directly a health issue, poor thermal conditions can exacerbate dissatisfaction, productivity and morale.

Heating, cooling and humidity control are major energy factors in offices and maintaining a comfortable thermal environment will have a major impact on energy use.

Relative Humidity Control

Humidity control is both a comfort and a health issue. Low humidity levels irritate the bronchia producing more respiratory complaints and also allow dust to disperse more readily. High humidity levels support dust mite and fungal growth and allow airborne bacteria and viruses to survive for longer periods.

HVAC Control

Poorly conceived partitioning and space planning can create uneven and obtrusive heating and cooling control throughout the interior of occupied spaces. Coordination is required between the HVAC supply and the organization of internal spaces and partitioning.

Solar Heat Gain

Air temperature, air movement and relative humidity can be controlled by the mechanical systems. Thermal and visual discomfort can occur through sunlight falling directly in the workplace in the absence of effective solar control.

Thermal Mass

Thermal mass offers the twofold advantages of moderating the temperature of occupied spaces during conditioned periods and thereby minimizing or eliminating the need for mechanical cooling.

Improved control of the thermal environment can be achieved by:

• Providing heating and cooling devices in close proximity to occupants;
• Where general space heating and cooling is provided, considering the effects of partitioning and space planning to ensure even heating and cooling control throughout the interior of occupied spaces;
• Providing for some flexibility, or ability to control local thermal conditions based on specific occupant requirements, while still maintaining reasonable limits overall;
• Designing zones that are as small as is practical;
• Providing controls which correspond to interior partitioning;
• Providing controls which are readily accessible from the space to which they are connected and are easily comprehensive to occupants will encourage their use;
• Planning for the careful admission of direct sunlight into the building interior using effective solar control devices on windows;
• Using the thermal mass inherent in the building to regulate temperature variations.

2.2 Improving Indoor Air Quality

Appropriate indoor air quality is defined as the absence of air contaminants which may impair the comfort or health of building occupants. Indoor air quality is most appropriately addressed first by removing or controlling sources of pollution and secondly by providing effective ventilation.

Indoor air problems can be minimized by reducing or eliminating contamination created:

• By materials enclosing and within the occupied spaces;
• By occupants, equipment and processes within the occupied spaces;
• Within the mechanical system and its distribution system;
• By the introduction of poor quality outside air due to local or regional air pollution or through inappropriately placed intakes.

2.3 Controlling Sources of Pollution

2.3.1 Finishing Materials

Because finishing materials are those directly enclosing an occupied space, their selection is critical from an indoor air quality standpoint.

The shift towards synthetic materials has had a deleterious impact on Indoor Air Quality:

• Thirty or forty years ago, linoleum, a linseed oil and cork product which is highly durable, was one of the most common types of resilient flooring. Today vinyl, derived from petrochemicals, has largely replaced it;
• Polyvinyl chlorides have been substituted for some metal components and natural rubber has been replaced by neoprene and styrene-butadiene;
• Wood boards that were used as sub floors, and finished flooring have been replaced by plywood and particle board made with glue;
• The urea-formaldehyde binders in particle board and interior rated plywood release chemicals such as acetone and formaldehyde into the indoor environment.

With the exception of asbestos, the components of existing buildings have released much of their volatile contents through years of out-gassing and are now relatively benign. Keeping them in place, if possible, will reduce the amount of emissions from new materials. However, indoor air quality problems will also derive from the damaging effects of water, floor maintenance practices or the replacement by new finishing materials during a renovation.

Building Moisture

Moisture damage in buildings caused by roofing failures, plumbing failures and other accidents can cause microbial contamination of absorbent materials leading to sour odours and possible growth of pathogenic bacteria and fungi.

Indoor air quality can be improved by:

• Evaluating materials for off-gassing, stability under exposure to varied temperatures and moisture levels, resistance to soils and odour contamination, maintenance requirements and durability, with particular attention given to:
• Those used in large quantities
• Those having potentially high emission rates
• Those located near the occupant's breathing zone or exposed directly to the ventilation air;
• Taking care to specify that exposed surfaces of materials containing contaminants, i.e., particle board (containing formaldehyde), be sealed or encapsulated and unused assembly holes be plugged during manufacture;
• Requesting written recommendations from the manufacturer regarding maintenance methods having minimal impact on building air quality to ensure maximum effectiveness of product use through time;
• Adequately repairing any moisture damage and, if necessary, discarding contaminated insulation, carpet, etc.

2.3.2 Paints

Interior paints are sources of serious exposure to trades and building occupants throughout their curing period. This period may be several weeks in length and extend well into the occupancy period of a new or renovated building.

Paints listed by the Environmental Choice Program^[8] or other equivalent authority are preferred choices.

Indoor air quality problems with paints can be reduced by:

• Specifying water based paints with reduced volatile and preservative content, those which meet EcoLogo standards for reduced solvent content, or those which are formulated for minimal VOC emissions;
• Specifying paints which contain no mercury, lead, hexavelant chromium or cadmium compounds in their formulation or tints.

2.3.3 Adhesives

Solvent based adhesives are environmental hazards and are toxic to handle. Both the solutions used to clean up solvent based adhesives, as well as the unused adhesive itself, are hazardous wastes and need be taken to a hazardous waste collection service.

Low emission adhesives are water based and formulated for low emissions and low toxicity according to Environmental Choice or other comparable standards. These adhesives contain virtually no aromatic solvents; do not have the strong odours of other adhesives; are safer to install; and have less manufacturing impact and toxic waste.

Indoor air quality problems with adhesives can be reduced by:

• Specifying construction adhesives with low emissions during curing (see paint recommendations above).

2.3.4 Floor Coverings Floor

Floor coverings are important sources of volatile organic compounds, dust, and fibre release due to their large surface area with both short and long term consequences.^{[9, 1O]}

The interaction of indoor air pollutants with interior surfaces is an important indoor air quality problem. A surface can act as a sink by absorbing VOCs emitted from another material, and later desorbing that VOC into the space. Surfaces with the highest accessible surface per unit area such as acoustic tile, carpet and upholstery fabric have the highest sink capacity.

Sources of volatiles and dust from both textile and non-textile floor coverings can be reduced by specifying low emission, easily maintained floor covering construction and low emission installation methods.

A "low emission" resilient floor covering is one which:

• Contains no soft, flexible vinyls (e.g., resilient PVC);
• Contains little or no chloroprene rubber, styrene, butyl rubber or latex;
• Is factory sealed with a durable, no-wax finish.

Carpet

Although natural fibre carpets offer many environmental qualities, cost and limited durability preclude their use in many applications.^{[11, 12]}

Carpet choices are often limited to those made of synthetic fibres from petroleum sources - nylon, polyester, polypropylene:

• They are manufactured using continuous looms, usually by bonding the fibres to a backing with flexible latex glue;
• Gases emitted from the latex backing and fibre treatments are a source of indoor air pollution;
• The carpet and under-cushion are typically fixed to an unfinished wood or concrete sub-floor with glue;
• Carpet adhesives especially when solvent based are hazardous to manufacture, install, and present disposal problems;
• Synthetic carpet is non-biodegradable and once discarded and dumped in the landfill, will remain for decades.

A "low emission" carpet installation is one which:

• Eliminates synthetic latex bonding materials;
• Eliminates topical stain resistance materials;
• Eliminates flame retardants;
• Eliminates foamed rubber or plastic backing or pads;
• Has pile which resists soiling and allows easy air movement for cleaning.

Ideally, all carpet installations should be either stretched-in, tackless strip, velcro adhered backing, or "dry adhesive".

However,

• The relative large areas of carpet used in office areas often make it difficult to avoid movement or to use tack strips;
• Any seams would be vulnerable given the considerable traffic to which the carpet can be subjected. Dry adhesive has merits for these reasons, and is releasable for repairs.

Indoor air quality problems with floor coverings can be reduced by:

• Selecting resilient flooring in common areas that are constructed without soft, plasticized vinyl or rubber and laid with low-toxicity adhesive or without adhesive;
• Keeping carpets away from entrances where they will become soiled and away from water sources;
• Selecting carpets which have fusion bonded, needle- punched or other low emission backing specifically designed for low emission characteristics, and having low pile, tight loop construction installed with dry adhesive minimal adhesive or without adhesive;
• For large carpet projects, requiring detailed testing of the carpet systems, including adhesives and seam sealants and having the carpet manufacturer specify the adhesive and request a warranty of total VOC emission for the installation;
• Specifying off-site airing-out of carpets by requiring the manufacturer or supplier to open packaged materials and store them in a heated and ventilated warehouse from the time of manufacture until delivery to the site.

Floor Maintenance

Air contaminants from maintenance (cleaners, waxes, carpet cleaning and pesticides etc.), are a continuous concern, emphasizing the importance of the selection of low maintenance finish materials.

2.3.5 Gypsum Board

Water-resistant gypsum board, especially those with toxic additives used for retarding fungus growth, can pose environmental problems. The additives incorporated in gypsum board to increase its moisture resistance, may contain chemicals to resist fungus contamination.

The water-resistant agents add a petroleum-based component of the board, increase the energy required for manufacture, and renders the material unfit for recycling.

Gypsum fibreboard offers many improvements:

• It contains fiberized post-consumer newsprint and, along with wood fibre for reinforcement, is mixed with the gypsum before setting;
• It requires less energy and generates less pollution;
• It does not have a Kraft paper finish and, as such, has a much harder surface than conventional gypsum board;
• It is not as susceptible to tearing, bulging, and scratching;
• Because of the exactly produced edges, which permit tighter installation fit, less joint compound is required.

2.3.6 Building Flush-Out

The level of volatile organic compounds from construction and interior finish materials is highest immediately after installation and declines with age.

A building flush-out is a sustained period of full ventilation, using 100% outdoor air prior to building occupancy to reduce levels of residual volatiles. A period of at least one week is recommended. A 'flush-out' differs from a 'bake-out' in that the latter is the provision of continuous or periodic ventilation while maintaining elevated indoor air temperatures. Concerns here are the possible warping and damage of interior finishes at these sustained temperatures (approx. 27-28°C).

A building flush-out is an essential protocol, but effective source control will minimize or eliminate the need for a building bake-out.

The level of volatile organic compounds from construction and interior finish materials can be diminished by:

• Sustaining a period of full ventilation, using 100% outdoor air after renovation or construction prior to building occupancy to reduce levels of residual volatiles, for a period of at least one week.

2.4 Isolating Pollutant Sources

Office buildings which contain uses such as printing shops, graphics departments etc., producing air contaminants which may affect the health and comfort of office occupants must have provisions to prevent entry of contaminants.

Though fire code and health and safety regulations govern this matter, compliance may not prevent comfort complaints or produce "fail safe" conditions.

Fully isolating distinct sources of pollution by appropriate building zoning, air pressure differentials, provisions for ventilated vestibules, fully separated ventilation systems or other methods will often be required to minimize indoor air quality problems.

Known pollutant sources can be isolated by:

• Making provision to prevent transfer of contaminants which may affect occupant health and comfort to other occupied zones.
• Providing air locks and pressurization to reduce the entry of vehicular exhaust and other outside contaminants.

2.5 Minimizing Contamination within the HVAC System

Two potential air quality issues and associated health risks in HVAC systems are:

• Loose mineral fibres within the air distributions system, particularly from silencers or return plenums over suspended ceilings, which enter the occupied space;
• Standing water in ventilation systems which incorporate a chiller, humidifier, dehumidifier, heat exchanger, air washer or any other device which may be expected to introduce moisture into the system, either by condensation or moisture injection, can support growth of pathogenic bacteria and fungi.

2.5.1 Mineral Fibre Related Problems

Duct Liners

Conventional wisdom is to minimize or eliminate the use of liner products containing mineral fibre used for acoustic and thermal insulation inside HVAC ducts since:

• Fibrous liners trap dust, making air filtration and duct cleaning less effective;
• Accumulated dust and debris will support microbial contamination if moisture is present;
• Deteriorating fibrous liners are a source of hazardous mineral fibres.

Liner encapsulation is the most common solution today, but requires regular inspections to ensure its integrity.

Ducted Returns

Ducted returns are more likely to stay balanced, less prone to disturbance, deterioration, and dust contamination and are more readily cleaned than non-ducted systems.

Providing ducted returns may require higher ceilings (often available in older buildings) or larger return fan motors and use additional energy, but improved ventilation effectiveness and reduced maintenance are important benefits.

Filtration Performance

Common filtration equipment is not capable of effectively trapping smaller particulates, especially those less than 5 microns. Improved filter systems can remove this particle size range, both protecting building occupants and reducing equipment cleaning requirements.^[13]

Loose Mineral

Fibre Quantities of un-contained mineral fibre materials, particularly where exposed in ceilings used as air plenums, because some released fibres are certain to enter the occupied zone. This includes sprayed acoustic coatings and fire protection to the building structure retardants containing more than 10% mineral fibre, and acoustic and thermal insulation batts and panels with exposed glass or mineral fibre materials.

Contamination within the mechanical system can be minimized by:

• Using only minimal amounts of fibrous liners inside HVAC ducts for acoustic and thermal insulation and limiting these uses to the return air path;
• Avoiding the use of suspended ceilings as return air plenums and using ducted returns;
• Where conditions warrant, specifying filter systems which can remove particle size less than five microns to protect building occupants and reduce equipment cleaning requirements;
• Avoiding quantities of uncontained mineral fibre materials in the building, particularly where exposed in ceilings used as air plenums, because some released fibres are certain to enter the occupied zone.

2.5.2 Water Related Problems in Mechanical System

Where the heating, cooling and ventilating system is installed in compliance with MD 15000 recommendations for prevention of standing water, no standing water will normally occur in the air path.

Humidification and condensate systems must be designed and maintained to minimize moisture in ducts and moisture contamination of duct liners.

• Installing the heating, cooling and ventilating system in compliance with MD 15000 and ASHRAE recommendations for prevention of standing water.
• Designing humidification and condensate systems to minimize moisture in ducts and moisture contamination of duct liners.

Cooling Towers

Cooling towers can become sources of hazardous pathogens because they provide conditions for breeding microbes. Therefore, they must be treated. However, treatment methods include caustic and toxic chemicals which are also hazardous.

Treatment by the least hazardous means and spray control design are the most appropriate means of reducing risks from cooling towers:

• The risks from microbes and treatment chemicals can be minimized by locating and designing cooling towers to prevent spray from entering the building and from falling on public areas;
• There is a variety of chemical treatment methods available using different classes of bactericides, fungicides, algicides and buffers or corrosion inhibitors.

Health issues associated with cooling towers can be minimized or eliminated by:

• Locating and designing cooling towers to prevent the release of spray containing microbes and treatment chemicals from entering the building and from falling on public areas.

2.5.3 Access for Maintenance

Many health issues derive from inadequate maintenance of the mechanical systems.

Minimizing indoor air quality problems will require that building operators have easy access to all critical parts of the ventilation distribution system.

Maintenance procedures can be facilitated by:

• Providing sufficient space and access to all relevant parts of the mechanical and ventilation systems in order to facilitate effective, regular maintenance.

2.6 Reassessing the Location of Air Intakes

Many indoor air quality problems begin by the introduction of poor air from the outside. Some sites may be located where they are relatively free from urban and industrial pollution. Others, however, are not and may require extraordinary filtration of outdoor air.

Poor intake air quality may also occur as a result of buildings themselves and their proximity to adjacent vehicular access.

Hazardous Outdoor Sources

Building air intakes must be adequately isolated by both vertical and horizontal distance from sources of vehicle exhaust, cooling tower spray, combustion gases, laboratory exhausts and other hazardous air contaminants.^[14]

Unpleasant Outdoor Sources

The location of intakes near sources of nuisance odours such as garbage collection areas and plumbing vents can lead to air quality complaints. Problems can be reduced by isolating building air intakes by both vertical and horizontal distance from sources of nuisance air contaminants.

Re-Entrainment

Poorly conceived and located building exhausts can lead to the "re-entrainment" of exhaust air into fresh air intakes. Locating building exhausts well above and horizontally separated from intakes is the most effective means of minimizing this risk.

Air Scrubbing

Office buildings those areas which exceed ambient air pollution guidelines, may require the use of adsorption media to pre-clean ventilation air (e.g., activated carbon filters).

The introduction of the best quality air from the outside can be improved by:

• Adequately isolating building air intakes both vertically and horizontally from sources of vehicle exhaust, cooling tower spray, combustion gases, laboratory exhausts and other hazardous air contaminants;
• Adequately isolating building air intakes both vertically and horizontally from sources of nuisance air contaminants such as garbage collection areas and plumbing;
• Adequately isolating building air intakes from intakes to prevent "re-entrainment" of exhaust air.

2.7 Providing Effective Ventilation

Applicable Standards

Ventilation systems should be designed to meet or preferably exceed those specified in MD 15000 at the minimum preset ventilation rate, while heating and cooling systems simultaneously maintain thermal comfort within the recommended range.

2.7.1 Ventilation Effectiveness

It is insufficient to consider only the amount of air delivered to a space - the air must be delivered to the occupants. The more directly supply air reaches the "breathing zone", the higher the ventilation effectiveness. Ventilation effectiveness depends on the:

• Path by which supply air moves through an occupied space and reaches an exhaust or return;
• Directness of delivery of ventilation air to the occupants, i.e., diffuser type and location;
• Placement of obstructions to air movement such as partitions and acoustic barriers.

Providing effective ventilation requires coordination between architect, interior designer and mechanical consultants.

Ventilation effectiveness can be improved by:

• Analyzing the impact of air supply and return locations on airflows in typical and unique spaces in order to eliminate short-circuiting and dead air zones;
• Using the most appropriate diffusers and velocities for a given space;
• Where possible, locating return air opening no more than 3m from any typical copy machine to provide dilution of emissions, or dedicated exhaust.

2.7.2 Outdoor Air Economizer Capacity

The outdoor air economizer cycle design allows the use of outdoor air for building cooling during mild weather by increasing the proportion of outdoor air mixed with return system air.

Increasing outdoor air proportions also typically improves indoor air quality and is useful for "flushing periods" at morning start-up and during interior renovations and maintenance.

The ideal performance of the ventilation system will be attained by:

• Specifying 100% economizer capacity, i.e., all supply air can be outdoor air when required.

2.8 Improving Lighting Quality

Quality illumination is a fundamental necessity for comfort and productivity in the workplace. Well designed, controlled and integrated daylight and electric lighting is necessary for achieving a satisfying and glare-free environment for office work, particularly for workstations with video display terminals (VDTs).

Current IES recommendations implicitly accept the notion of a less general illuminance level in the space but higher in the vicinity of the tasks. Lighting must be designed and provided to satisfy the visual needs of the occupants. Merely complying with the specified illuminance levels for the task will not satisfy this requirement.

Providing a comfortable lighting balance, limiting the effects of transient adaptation and minimizing disability glare can be achieved by:

• Using IES recommendations as a general guide for maximum luminance ratios between the task and its surrounding, particularly for workplaces using Video Display Terminals (VDTs).

2.8.1 Lighting Distribution

IES recommendations provide a general guide for maximum luminance ratios between the task and its surroundings to achieve a comfortable balance and limit the effects of transient adaptation and disability glare.^[15]

These recommendations are particularly important for work-places using Video Display Terminals (VDTs).

Variety in Lighting

Many existing office buildings have ceiling luminaries placed on a regular grid to provide requisite lighting levels. These general lighting strategies often create monotonous luminous conditions and veiling glare on VDT screens which reduce visual comfort and productivity.

Visual comfort is a function of a variety of physical and psychological factors, IES luminance ratios are by no means absolute, especially when dealing with daylight. Although very bright or dark areas within the field of view may be distracting, variation within these prescribed limits is also desirable to avoid a monotonous environment.

Task-ambient lighting and non-uniform lighting strategies can provide greater definition to the interior, producing more interesting and appropriate lighting conditions.

The quality of the lighting can be improved by:

• Enhancing the visual comfort of occupants engaged in specific tasks by providing the appropriate illuminance, distribution and avoidance of glare;
• Providing users with the ability to control the amount and direction of light at their workstation;
• Enhancing the visual definition of spaces and overall impression created by the space by providing a sense of orientation, guidance, visual focus, spaciousness, privacy, etc.;
• Providing a distribution of lighting within the space such that the surfaces and objects that are of significance to the occupants are lit in an appropriate and relevant manner;
• Providing visual interest by incorporating a variety of fixture types, directed diffusers, indirect lighting, highlighting or other features;
• Designing an effective lighting strategy which recognizes and provides for both ambient light and task light which are fully integrated with each other in the architectural concept and other systems.

2.8.2 Lighting Equipment

Lamps

Two significant lamp characteristics are:

• Luminous efficacy (LumensNVatt)
• Colour Rendering Index - a minimum acceptable value for office work being 75.

Smaller, T-5, T-8 or T-10 lamps with triphosphor coatings offer improved colour rendition and energy efficiency. Trichomatic phosphor lamps use a blend of three rare-earth phosphors that peak in the red, green and blue wavelength regions to create "white" light.

Ballasts

Standard lighting ballasts operate lamps at a 60 hz frequency. While ballasts are new and lamps are replaced regularly, there is no visible flicker, but as ballasts and lamps wear, flicker often begins. Flicker is a distracting phenomenon and can be a serious problem with video displays, actually affecting comfort and productivity. High frequency ballasts make lamps perform longer without flicker.

For locations sensitive to electronic interference, the use of hybrid ballasts is an asset. They combine the benefits of lower operating energy with reduced interference.

The quality of lighting systems can be improved by:

• Specifying lamps with colour rendering indexes greater than 75;
• Specifying electronic ballasts.

2.8.3 Direct lighting and Indirect Systems

Whereas direct lighting is inherently more energy efficient, indirect systems that are integrated with furniture or ceiling systems can provide low-glare and soft, ambient lighting in the workplace.

Diffuse light bounced off the ceiling greatly reduces the potential for direct or indirect glare resulting from sharp contrasts in lighting and is preferred by VDT users.

Combining direct with indirect, or direct/indirect systems with adjustable distribution, can provide both improved lighting quality and energy efficiency.

The quality of direct lighting systems can be improved by:

• Selecting fixtures which minimize direct glare and avoid monotonous or disturbing arrangements;
• Minimizing differences between a bright recessed ceiling fixture and adjacent unlighted ceiling tile;
• Specifying luminaries and lighting systems employing advanced optical systems and efficient reflector materials, such as polished reflectors and parabolic diffusers equipped with louvres for adequate cut-off of light at angles exceeding 45^' from horizontal.

Indirect lighting can be utilized to:

• Reduce the potentially overall bland appearance often associated with totally indirect lighting strategies;
• Minimize "hot spots" on the ceiling plane.

2.8.4 Natural Lighting

All office buildings typically have windows. However, the interior organizations of interior spaces, height, colour and orientation of the partitioning, the electric lighting and associated controls, often do not take advantage of the potential natural lighting.

If carefully admitted into building interiors, natural light can enhance the environmental quality of the workplace. These benefits can be translated into improved occupant satisfaction and enhanced productivity. Under the right circumstances, a small amount of natural light can be as effective in increasing visual performance as larger amounts of conventional overhead electric lighting.

If major changes to the building's glazing are contemplated, the introduction of quality natural lighting should be an important consideration in the redesign, glazing choice, solar control and electric lighting control strategy.

Daylight

Daylight is typically always welcome in those spaces occupied for prolonged periods, providing that sky glare and the amount of light admitted can be adequately controlled.

Sunlight

The value of sunlight has little to do with quantity. It is more desirable to have a small amount of sunlight within the interior over an extended period of time rather than a large amount of short duration.

Direct sunlight may be an undesirable quality in many spaces within office interiors especially where VDTs are in use and where it falls directly on fixed workplaces. It also adds to the cooling load.

Improved daylighting can be achieved by:

• Planning the interior organization to maximize for the potential benefits of daylighting from existing window configuration;
• Recommending that the internal planning of partitions be organized to enhance the benefits of daylight;
• Selecting internal reflectances which maximize the reflection of daylighting deeper into the building interior;
• Examining the potential benefits and adverse effects of admitting sunlighting into the workplace;
• Planning the interior to provide the greatest possible visual access to the exterior.

Glare

Both direct and reflected glare reduce occupant satisfaction, productivity - initiating actions such as covering windows which ultimately reduces the amount of useful daylight to the building interior.

The use of innovative blinds with separate tilt control for upper and lower sections, or perforated fabric blinds, can achieve reduction in glare while maximizing daylight advantages.

Visual Contact with Exterior

Visual contact with the exterior is important in providing and maintaining cues regarding orientation, time of day, and weather:

• Glass assemblies which transmit more visible light provide an accurate perception of daylight conditions;
• Many types of tinted glass and solar control coatings reduce visible light to the point where daylighting opportunities are eliminated and accurate perception is lost;
• Minimum acceptable levels of glazing light transmission are around 30% but greater than 55% is preferable. Brightness enhancing glazings (e.g., bronze tints) can counter the reduction in the perception of daylight within office interiors.

2.9 Improving Acoustic Quality

Appropriate acoustic conditions are a fundamental necessity for comfort and productivity in the workplace. Very moderate systems noise can be an advantage but excessively low ambient noise levels (i.e., low background noise) can lead to a loss of acoustical privacy.

The acoustic conditions within the interior can be improved by:

• Controlling ambient noise entry, and excess internally generated noise at source to maintain appropriate acoustic conditions;
• Using appropriate acoustic separation rather than employing masking sound other than that provided by necessary equipment.

2.9.1 Flanking and Isolation

Noise generated within the building by occupants, their equipment and plumbing is also a common irritant in the workplace and is usually caused by poor sound isolation in floors and walls. This can be remedied, to a large extent, by acoustic barriers and isolation of sources. Measures to reduce sound transmission between occupancies and floors can reduce irritating noise from internal sources.

The integrity of acoustical partitioning can be maintained by:

• Extending partitions above the suspended ceiling;
• Eliminating holes for ducts, pipes, conduits, cables etc.;
• Providing appropriate acoustical treatment on doors, sidelights, etc.;
• Minimizing or eliminating break-in and break-out sound transmission through air ducts passing through the partition.

2.9.2 Low Equipment and Equipment Room Noise

HVAC mechanical noise is a common irritant in the workplace and is usually caused by worn or poorly adjusted equipment or poor sound isolation:

• Noise may be amplified by vibrating sheet metal parts and carried long distances by ducts;
• Equipment rooms are a substantial source of noise in adjacent spaces or in ducts unless designed to appropriate noise reduction standards.

Low noise equipment and isolation of mechanical equipment to achieve a high standard of noise reduction is a valuable comfort asset in the workplace.

Noise generated within the building by occupants, their equipment and plumbing can be controlled by:

• Blocking flanking sound paths through fixed walls and floors and isolating plumbing noise from the structure;
• Evaluating all HVAC systems and equipment rooms for compliance with a NC (Noise Criteria) of 40 or better for all occupied zones.

Window STC

Traffic, airport, rail and industrial noise is also a common irritant in the workplace and is caused by poor sound isolation by envelope elements, particularly windows. It is typically most severe on the first three floors of buildings in dense urban areas or near major transportation or industrial noise sources. Windows designed to reduce sound transmission are readily available and are an effective remedy.

2.10 References

1. Air Quality linked to Productivity, The Construction Specifier, Construction Specifier Institute, USA, July 1994. (back to 1)

2. MD 15000 - Environmental Standards for Office Accommodation, Public Works and Government Services Canada, November 1994, Ottawa. (back to 2)

3. ASHRAE Standard 55-1992, Thermal Environmental Conditions for Human Occupancy, American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA. (back to 3)

4. ASHRAE Standard 62-1989, American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA. (back to 4)

5. CSA Z 204-94, Guidelines for Managing Air Quality in Office Building, Occupational Health and Safety, Canadian Standards Association. (back to 5)

6. IESNA, Recommended Practice, Illuminating Engineering Society of N.A., RD-1 (1993), New York, NY. (back to 6)

7. Pasini, l., Office Lighting, Design Standard RPS/DGSI 1-4:951 Real Property Services Branch, Public Works and Government Services Canada, 1994. (back to 7)

8. ECP, Environmental Choice Program, Environment Canada/TerraChoice Environmental Services Inc., Ottawa, Ontario. (back to 8)

9. Leclair, K., and Rousseau, D., Environmental by Design, Vol. 1: A Source-book of Environmentally Aware Interior Finishes, Hartley and Marks, Vancouver, 1992. (back to 9)

10. PWGSC, The Environmentally Responsible Construction & Renovation Handbook, Public Works and Government Services Canada, Cat. No. En 40-481/1994E. (back to 10)

11. Leclair, K., and Rousseau, D., 1992. (back to 11)

12. PWGSC, The Environmentally Responsible Construction & Renovation Handbook. (back to 12)

13. ASHRAE Standard 52-76, "Atmospheric Dust Spot Method", American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA. (back to 13)

14. Cole, R.J., Rousseau, D.L., & Theaker, l.G., Building Environmental Performance Criteria (BEPAC), The BEPAC Foundation, Vancouver, BC, 1993. (back to 14)

15. IES, VDT Lighting - IES RP-24, IES Recommended Practice for Lighting Offices Containing Computer Visual Display Terminals Illuminating Engineering Society of NA, New York, NY. (back to 15)

Document "An Architect's Guide for Sustainable Design of Office Buildings" Navigation

• Previous Page
• Table of Contents
• Next Page