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Abstract

In the new millennium; the American Institute of Architects (AIA), the American Society of Heating Refrigerating and Air-conditioning Engineers (ASHRAE), United States Environmental Protection Agency (USEPA), facility managers and most international organizations are stressing the need for more environmentally conscious facility designs. The sustainable design approach not only emphasizes energy savings, but also accounts for issues such as impact on the local economy, resources, transportation, waste management, water management, and air quality.

In 2000 the LEED® (Leadership in Energy and Environmental Design) certification system was unveiled for the evaluation of the sustainability of architectural projects. Refer to the LEED® criteria for sustainable options.[1] This criteria has been selected by National Oceanic & Atmospheric Administration (NOAA) to be applied to the design of its Honolulu Laboratory Renewal Project. The sustainable design process implemented by the design team includes: project approach, evaluation criteria, benchmarks, design concepts and future trends.

Research facilities are energy intensive and potentially hazardous in nature. Indoor air quality, ventilation and energy conservation requires integrated architectural and engineering.

 

Introduction / Overview of Sustainable Design

For those who are unfamiliar with the term “Sustainable Architecture”; it refers to a design that has taken into consideration the total impact of the building on the environment and society including the following impacts: (A) site selection, (B) transportation, (C) rain water management, (D) localized warming referred to as “heat islands”, (D) light pollution, (E) water efficiency, (F) optimized energy usage, (G) improved atmospheric performance, (H) material waste reduction, (I) resource reuse, (J) impact on local and regional economies, (K) use of renewable materials, (L) protection of endangered animals and plant species, (M) improved indoor environmental health, (N) use of natural day-lighting, and (O) other features that improve performance and functioning of the built environment.

 

Architectural Design Considerations

Architectural overview: An early sustainable opportunity is the selection of the building site. The architect’s involvement in the site selection process can help the client make early sustainable decisions that save project funding and natural resources. Once the site has been determined, the architect can better assemble a consultant team which can provide the design services specific to the site.

Form, envelope, and fenestration: The site parameters influence the building form in many ways. The bearing capacity of the soil generally limits the number of building stories that can be economically constructed. In most cases foundations systems become more expensive when buildings are higher than three stories. From an energy perspective, compact buildings, tend to be more energy efficient in cooling and heating applications. In most cases, single story facilities have lower foundation costs but higher HVAC costs. This is due in part to the high heat gain incurred by the relatively larger roof area. Two and three story facilities tend to be most economical since they have relatively low cost foundation systems, compact HVAC distribution systems and reduced roof heat gain due to the reduced size of the roof. Buildings with their long dimension oriented in the east west direction tend use less energy due to the reduced heat gain from the early morning and late afternoon solar exposure. Additional savings can be obtained by reducing the glass portions of the building on the east and west facades of the building. [2] [3]

Significant cooling energy can be saved if the windows are protected from direct solar heat gain. This can be accomplished architecturally by the use of vertical and horizontal shading fins. Day-lighting can be similarly achieved with the use of solar light shelves and other architectural devices that reflect indirect light into the building. Computer programs that analyze solar heat gain on vertical building surfaces can be used to maximize the cost effectiveness of the solar shading devices. Properly oriented skylights, light chimneys, and light tubes can be a good source of day- lighting the interior portions of the building. Achieving good day-lighting in a building is also influenced by increasing floor to finished ceiling heights to 10 feet or more. Good design also dictates the placement of habitable spaces in day-lit zones.

Case Study: National Marine Fisheries Service (NMFS) Honolulu Laboratory Renewal Proiect: An example of a sustainable laboratory project is the U. S. National Oceanic and Atmospheric Administration’s (NOAA), National Marine Fisheries Service’s (NMFS) Honolulu Renewal Laboratory consisting of approximately 110,000 square feet (11,000 square meters) of offices and laboratories.

U. S. National Oceanic and Atmospheric Administration's (NOAA) National Marine Fisheries Service's (NMFS) Honolulu Renewal LaboratoryOne of the main sustainable features of the project design was the site placement of the building. Good energy efficient design dictates that the building be oriented on an east/west axis. The NOAA project site geometry however was constrained to a north/south axis. The solution was to distribute the building program into three separate rectangular towers along east/west axes connecting them with a north/south directed circulation spine. This orientation and massing was critical in both reducing solar gain and maximizing natural ambient day-lighting, thereby reducing building cooling loads and lighting energy.

Integrated design decisions: Design teams that encourage professional discipline interaction, understanding, and cooperation, foster the best design solutions. As an example, the architect needs to know what kind of heating and cooling systems the engineer is considering during the schematic design process in order to seamlessly integrate it with architectural solutions to maximize total building performance. Conversely, it is also helpful to the engineers to understand the importance of the architectural massing and form for them to apply the necessary civil, structural, mechanical, and electrical engineering solutions that do not inhibit but strengthen the overall design solution. In a similar manner, the architect and interior designer working together, achieve interior laboratory, office, and support area planning solutions that are functional, practical and sustainable.

Material Selection: Product research for sustainable buildings takes longer since more parameters need to be considered when making material selections. The materials for the Honolulu Laboratory Renewal Project were selected based on criteria that promoted the design intent and a sustainable design solution. Primary criteria were: (A) client preferences, (B) contextualism with surroundings, (C) low cost, (D) low embodied energy, (E) low VOC (volatile organic compounds) off- gassing (F) high use of local materials, (G) compatibility with the climatic conditions, (H) use of natural materials, and materials with recycled content.

Interior design decisions: The interior designer’s job is to balance sustainability, functional considerations, cost, creativity, and design consistency. The interior designer must work closely with the architectural designer, engineers, and energy consultant to achieve the functional and sustainable goals consistent with the ultimate project objectives.

The relationship between the material selections and the methods of its application are critical to the building’s performance. Adhesives, sealants and coatings need to be considered at the time the material is selected to assure that the VOC off-gassing standards set for the project are met. One tool used in the selection of products is the BEES computer program that was developed by National Institute of Standards (NIST). This system is helpful in comparing two different generic products related to various sustainable criteria. The BEES software helps compare economic performance by life-cycle stage and environmental performance, rating the generic products related to: (A) global warming contribution, (B) acidification development, (C) eutrophication, (D) natural resource depletion, (E) solid waste contribution, and (F) indoor air quality.

 

Engineering Design Considerations

General: The building envelope’s design incorporates excellent shading provisions to minimize entrance of solar heat. Fenestration is single-glazed since exterior-to-interior temperature difference will not exceed 9°C, and will average less than 2°C, year around. The glass shading coefficient is 0.41. Upper portions of vertical glazing on each story are for daylighting with a shelf also shading the window below.

U. S. National Oceanic and Atmospheric Administration's (NOAA) National Marine Fisheries Service's (NMFS) Honolulu Renewal LaboratoryThe building’s arrangement, essentially three east-west oriented wings, minimizes solar load and makes daylighting of offices more efficient, since there is very little west fenestration, with office windows generally north and south. Most of the office area is in the South Wing and laboratories in the North Wing. Mechanical and electrical systems are designed to meet the project’s objective: functional, sustainable and energy-efficient, contractible within budget. At this writing the design is schematically complete but details are still under development.

Available energy sources at the site include adequate electric utility power and piped synthetic natural gas. Diesel oil is readily available, but fuel costs are high. Engine- driven refrigeration would have a far higher energy cost than electric motor driven vapor-compression equipment. Waste heat is recovered and solar energy is used in the design to a significant extent.

To optimize HVAC systems efficiency, the concept separates HVAC functions of cooling, ventilation and dehumidification. Decoupling of these functions, which are normally interdependent, allows the optimum process for each to be used. This design concept leads to a far more specialized approach to each function without the requirements of one function driving the efficiency of another. (e.g. in most HVAC systems for tropical climates, chilled water is cooled to a temperature needed for dehumidification which is lower than that are required for cooling).

Dehumidification: All of the air introduced into the building will be pre-conditioned, both cooled and dehumidified, to the extent that the entering air dew point does not exceed desired room dew point. The pre-conditioning system is roof-mounted and uses a liquid desiccant dehumidification process for the outdoor air. This process uses a lithium-chloride liquid desiccant system permitting one regenerator to serve dehumidifiers in two outdoor air pre-conditioning units. A roof mounted evacuated- tube solar collector array heats water to a maximum of 82°C for regeneration of the desiccant. The liquid desiccant process also kills 98% of airborne bacteria.

Ventilation: Ventilation is designed to comply with ASHRAE Standard 62-1999 requirements. Outdoor design conditions are 31°C dry bulb, 23°C wet bulb for cooling; with 24°C wet bulb and mean coincident dry bulb 30°C representing peak moisture-load weather. No space heating is required; lowest local dry bulb ever encountered is 12°C. The 99 percent annual cumulative frequency of occurrence of cold temperature is 17.2°C.

The air conditioning systems are designed to minimize the size and extent of ducts and piping while providing sufficient zoning and proper controllability. The preconditioned outdoor air is ducted to space-conditioning air handling units. Each wing has one air-handling unit per floor, with variable-speed drive fan, which supplies all-outdoor air to the offices and laboratories. The air handling units for the building have to handle only about one-fourth the air flow rate of a conventional all-air system, with significant power saving. Chilled water coils in the building’s air handling units have two-way chilled water control valves to minimize pumping power by reducing system flow when any control valve is throttled at reduced load.

Cooling: Each office is a separately controlled zone. Principal means of cooling is by radiant chilled water ceiling panels. The interior load is kept low by the daylighting, lighting controls, and the pre-conditioned ventilating air. The panels are supplied with chilled water at 14°C, leaving at 16°C under full load with an average panel surface temperature of 17°C. The chilled water flow rate is controlled by a two-way valve and room temperature sensor with occupancy monitor.

A ceiling diffuser in the office supplies a small amount of conditioned air at about 16°C, about one and one half air changes per hour, sufficient to ventilate and pick up a little load, sensible and latent. This satisfies the ventilation requirements, and maintains the office at positive pressure relative to the corridors and outdoors. A damper closes the air supply if the office is unoccupied. The air is transferred by ducts to corridors, storage areas and toilets, and exhausted. Exhausted air runs through air to air heat exchanges to recover energy & cool incoming outside air.

To accomplish the efficient controlled operation of a zone, a digital thermostat is wall-mounted in the conditioned space. It controls a chilled water valve supplying the radiant ceiling panels. It receives input for the after-hours shut down of the building and contains a motion detector which shuts off the supply air damper and chilled water control valve when the room is unoccupied. It also overrides the ambient lightning’s sensor to shut off the lights when the room is unoccupied. When the zone is occupied, the light fixtures’ own ambient light sensor permits operation of the artificial lighting as needed.

The building’s air handling systems generally shut down outside normal working hours, but any occupied zone can manually override the shutdown of its respective air handling unit.
Use of desiccant dehumidification and radiant panel cooling permits operating the water chilling plant at a higher evaporator temperature. Typical all-air air conditioning requires chillers to deliver chilled water at 6°C or 7°C with this system. Chilled water supply can be as high as 13°C, since air handling units for the offices and laboratories need deliver air no colder than 16°C.

Laboratories are conditioned by a system similar to the offices. The supply air is not recirculated but is exhausted, together with exhaust from variable-flow fume hoods, in a general exhaust system, sized to keep laboratories at negative pressure relative to their surroundings. A separate “snorkel” exhaust system with flexible branch ducts and inlet hoods permits local exhaust at higher negative pressure from any specimen when required. A radiant ceiling panel is the principal means to cool the space. Directly in front of fume hoods, conditioned air at 22°C and 50 % relative humidity is supplied.

Typical clothing in Honolulu offices and laboratories is 0.5 clo insulating value or less. With a metabolic rate of 1.2 met or less, and a minimum air velocity of 0.40 mis, a predicted mean vote of 5 percent dissatisfied, the optimum possible, can be achieved with an air temperature of 26°C and 50% relative humidity. An all-air system’s air temperature would have to be at least 2°C lower for equivalent comfort.

Storage rooms are generally in the building interior, with very low cooling load. They are conditioned by transfer air at about 2 air changes per hour, exhausted to the general exhaust system. The entrance foyer is conditioned with a displacement ventilation supply system. Assembly and conference rooms are conditioned as for offices, but with a greater maximum supply rate of conditioned air. The parking garage is arranged for sufficient wall opening to permit natural ventilation. The building includes a kitchen and food service facility. Kitchen exhaust from cooking hoods conforms to NFPA 96.

Water Chilling Plant: The air conditioning design results in a very efficient chilled water system. The chilled water piping system is a primary-secondary system with a constant-speed primary pump for each chiller, and two variable-speed secondary pumps. This permits flexibility of chilled water distribution without extra complication in control of the chiller plant.

The chillers are selected for excellent part-load efficiency, with consideration that the available entering condenser water temperature can almost never be below about 25°C in Hawaii’s climate. Dual-compressor centrifugal chillers offer the best performance at the roughly 200 ton/ 800 kw water chiller load. A chiller selected to deliver 13°C chilled water has a coefficient of performance (COP) of 7 from full load to below one-fourth full load. With two chillers, the COP is above 8 nearly all of the time. Refrigerant is chlorine-free, low global-warming-potential HFC 1 34a. The chiller plant is controlled by the manufacturer’s microprocessor-based system. Heat rejection from the refrigerant compressors is handled by roof-mounted cooling towers. Chillers are mounted near the center of the roof to shorten chilled water piping and condenser water piping. The cooling towers also have to cool the water which removes heat of absorption, sensible heat from air cooling, and residual heat from the warm concentrated liquid desiccant returning from the regenerator.

Pumps for liquid desiccant system cooling water have variable speed drives. Condenser water pumps are constant speed to ensure sufficient flow for centrifugal compressors at light loads.
The cooling towers are selected to cool water at design load to a temperature of 29°C when entering air wet bulb temperature is 24°C. Cooling tower fan power and sound level are both quite low with axial flow fans. The fans have variable-speed drive for power saving at night, and when very low daytime loads are coincident with lower wet-bulb temperature.

Water, Waste and Drainage: The solar thermal collector system used for regeneration of the liquid desiccant has sufficient storage to provide full capacity over a period of several cloudy, rainy days. Domestic service hot water is also provided by the solar collectors. Back-up for the system is provided by a reciprocating water source heat pump using R-1 34a refrigerant, which can provide 71°C water, providing reasonable dehumidifier performance. A gas-fired hot water boiler is also being considered at lower first cost to provide the regeneration hot water, as well as the service hot water, but will have much higher operating cost.

Plumbing design includes low-flow water closets and urinals, with flow-controlled faucets on lavatories. Size of the facility and site mitigate against use of gray water, but site irrigation is supplemented from rain water storage tanks.

Potable water, from the Honolulu municipal system, is supplied at sufficient pressure that no service water pumps are needed.

Drainage sump pumps are provided at the basement level, discharging to a city storm sewer. Waste piping is discharged to a city sanitary sewer. Laboratories’ waste piping is chemical resistant, and provision is made for a dilution tank prior to discharge into the sanitary sewer. Compressed air, gas, and vacuum systems are provided to the laboratories.

Fire Protection: The building is completely protected by a wet-pipe automatic fire sprinkler system conforming to NFPA-13, and the building is completely protected by a fire alarm system conforming to NFPA.

Lighting and Electrical: Day-lighting is the principal source of illumination, supplemented by artificial ambient lighting by direct-indirect fluorescent lighting fixtures suspended from the ceilings and task lighting mounted on office furniture. Lighting intensity generally conforms to recommendations of the IESNA for the applications involved, with a low level of ambient lighting. Exterior lighting is minimal, but sufficient for security. Light fixtures contain their own ambient light sensor to turn off when day lighting levels are sufficient. A manual override can be operated by the occupant using an infra red link to the light fixture.

This results in an installation which is very flexible and economical on cabling. Each light fixture (8 feet long using 2 x 39 watt T5 lamps) is virtually self-contained requiring only a single power feed cable. No switching or control cabling is needed. Future relocations will be easier and will cause minimal wastage in cabling, switch drops etc.

Electric power is supplied at utility voltage, three-phase four-wire 208/120 volt, 60 hertz. The entire building works on 208/120 volt only thereby eliminating, energy losses & heat loads from step down tranferences. A diesel electric emergency generator is provided for essential services, life safety and egress systems, with a 48-hour supply tank.

Construction of the facility will include a modular wiring system for all receptacles & communication cabling in a readily removable and accessible raised floor system. Telecommunications, data and intrusion access systems will be included. The Government will provide computers and networking components. The building’s structural wiring system will conform to TIAIEIA 568-A-5.

 

Future Trends in Sustainable Research Facilities

The building described in this paper represents state of the art sustainable research laboratory design at this time. However, there are several emerging trends in building design that promise even greater environmental benefit.

The first is the trend towards even more sophisticated modeling of environmental conditions, which will allow mechanical systems to be further diminished in importance and passive systems to increase in importance. This can be seen in the design of recent buildings that (with the design assistance of Computational Fluid Dynamics CFD modeling) have been able to completely eliminate the need for mechanical systems.

A second trend is the focus on “provision of service.” Just as the engineer is becoming tasked with “providing comfort” rather than equipment, all of the other building systems are valued for their utility rather then their commodity. Companies are now available who will provide fresh clean carpet for the life of the building, rather than simply sell it to you once. Provision-of-service contracts are now available for plumbing, lighting, wall coverings, furniture, and other aspects of what used to be capital expenditures.

These higher efficiency, highly passive buildings are also starting a third trend, that of energy autonomy. Buildings are now built which are either “off the grid” in that they provide all of their own utilities and services, or they remain connected to urban infrastructure but use is primarily to sell services rather than purchase water and electricity. [4]

 

References
[1] U.S. Green Building Council (USGBC), LEED® 2.0, May 2000

[2] Haxton, Bruce M.; Laboratory Building – Cost Analysis and Control, University of Wisconsin, Designing Functional R & D Facilities, Novi, Michigan, September 1992.

[3] Haxton, Bruce M.; Comprehensive Master Planning Strategies for R & D Facilities; U. of Wisconsin, Designing Functional R&D Facilities, Perth, Australia, Oct. 1998.

[4] Olgyay, Victor, ENSAR Group, Environmental Sustainability Report for the developed design of the NOM Laboratory project, Boulder, Colorado April 2000