The Green Engineer Ideas


	The Green Engineer, LLP
Sustainable Design Consulting

Green Ideas: Economically Sustainable Items

Indoor Air Quality (IAQ) Management Plan
Frequently IAQ problems are caused by two sources: 1) contamination of the ventilation system during construction 2) Volatile organic compounds (VOCs) and other contaminants from newly installed materials. In order to prevent this the design team should develop and implement an IAQ Management Plan for the construction process, based on SMACNA "IAQ Guidelines for Occupational Buildings Under Construction." This provides for protection of ventilation system components during construction and cleaning of components prior to occupancy. The plan should also address the use of low VOC materials where possible.

Encourage Use of Recyclable Materials in Specifications
Recyclable materials can be reused when their life in this building is over. This reduces solid waste, pollution, and energy consumption. For example, aluminum, steel and copper can be recycled–but some plastics cannot. More investigation will enable us to discover additional opportunities.

Specify Minimum Recycled Content in Materials
By specifying materials with a recycled content, we increase demand for these materials. This encourages recycling, resulting in reduced solid waste, pollution, and energy consumption. Most steel and aluminum used in building has a high recycled content. Insulation and carpeting with high recycled content can also be used. Specifying packaging materials with recycled content is also viable. Again, more investigation by the design team will turn up other opportunities.

Encourage Use of Local Materials
Materials produced locally use less energy during transportation to the site. This reduces worldwide energy consumption.

LEED^TM Certification
The US Green Building Council is an industry wide consortium made up of architects, engineers, manufacturers, contractors, developers, and other members of the design and construction community. One important program recently developed by the USGBC is the "Leadership in Energy and Environmental Design (LEED^TM) Green Building Rating System." LEED^TM is a benchmarking tool, which allows building owners to demonstrate the "greenness" of their building, in comparison to other buildings. At present LEED^TM is in the pilot stage, with full rollout scheduled for March 2000.

LEED^TM certification demonstrates that the building is a green building. It also will help to keep the building "green" into the future, by providing an incentive for the continued use of green technologies in the building (operators will be less likely to turn off green technologies if doing so will result in loss of certification).

Contractor Uses a Construction Waste Management Plan
Waste Management plan shall be implemented to facilitate recycling, and insure proper disposal of non-recyclable materials.

Daylighting–Active Skylights–Maximize use of Natural Light
Daylighting provides several benefits: 1) use of energy for lighting can be reduced during daylight hours. 2) Natural lighting provides increased occupant satisfaction–a connection with the outside world. Energy efficient skylights will let in the desirable visible light, while blocking excess heat gain. As a more radical solution, some kind of "smart" skylight could be used. A smart skylight would open to allow natural light and solar heat gain during cold conditions, but block excess heat gain during the cooling season.

Lighting Controls–Daylighting Controls
In tandem with skylights and other daylighting opportunities, daylighting controls will sense light levels and adjust artificial lighting as required.

Building Purge Cycle Controls
Controls to allow a building purge cycle are inexpensive. When installed they allow the building contaminants to be purged prior to occupancy.

Heat Recovery for Pre-treatment of Outdoor Air
Places of assembly have large fresh air requirements. Heat recovery can be used to pre-heat or pre-cool outside air, using the exhaust air as the source. This will reduce energy consumption during wintertime, and during extreme summer conditions.

Thermal Storage at Plant
Thermal storage systems can be used to shave peak HVAC loads. By shifting condenser operation to the cooler nighttime hours, greater energy efficiency can be realized. (This may not be practical if significant evening occupancy is anticipated.)

Gas-driven or Steam-driven Chillers
Gas chillers use environmentally friendly natural gas, instead of electricity. Steam turbine chillers use steam to drive the refrigeration compressors. Both options may reduce pollution and reduce energy consumption.

Thermal Storage in Building Mass
Concrete slabs and other high thermal mass building elements can be pre-cooled prior to occupancy. This reduces peak load and allows load shifting to off peak hours.

For example, the Gap Building in San Bruno, California (Architect - William McDonough, with Gensler; Engineer - Arup) uses a raised floor air distribution system, combined with a concrete floor slab to reduce peak loads. In the cool evening hours, outside air is brought into the building, while warmer air is flushed out through roof monitors (which also act as a source of daylight). This action drops the temperature of the thick concrete floor slabs to as low as 60º F. During the day, the cooled slabs absorb some portion of the heat produced in the building, which results in an estimated 20% reduction in peak loads, according to the designers. The system is so effective, the local utility gave the Gap rebates for this thermal storage system.

Permanent Air Monitoring System–Demand Controlled Ventilation
A permanent air monitoring system verifies IAQ at all times. This can then be used to provide demand-controlled ventilation. The convention center will require significant amounts of ventilation when occupied, but much lower amounts at other times. Demand control ventilation will allow energy savings at off peak conditions, without compromising IAQ at peak load conditions.

Gray Water System
Wastewater from sinks, cooking etc. can be recycled for use in toilets and urinals. Opportunities for gray water recycling may be limited due to small amount of these types of uses in some buildings.

Evaporative Cooling
Chapter 19 of your 1996 HVAC Systems and Equipment ASHRAE Handbook covers evaporative cooling. The basic concept is pretty simple–a spray of water into an airstream causes the temperature to drop, due to the evaporation of the water. Unfortunately it also makes the airstream more humid. Evap coolers (or swamp coolers as they are sometime called) are used all over the southwest. They work best in hot dry climates. The major drawback is that they cannot drop the air temperature below the wet-bulb temperature, so on a humid day they don't do much. But they can be combined with conventional systems to reduce loads, especially in systems with high ventilation requirements, like for places of assembly or labs.

Measurement & Verification
Measure and Verification shall comply with DOE International Performance Measurement and Verification Protocol for Energy and Water Consumption. Designing and building a green building is not enough. We must insure that the building operates as designed. The DOE protocol provides a standard method of verifying building performance.

Smart Building
Buildings of the 21st Century will integrate the current DDC control technology with other building systems to create a "Smart Building." The Smart Building will anticipate the needs of the building users to provide improved comfort, greater user control, and better energy efficiency. Here are a few examples of how this can work:

Web-based control of building systems: Building occupants can adjust room temperature setpoints, change lighting schemes, or adjust any number of other systems through a password protected web page. An instructor could use this to set up a classroom in advance of a lecture.
Integration of HVAC and lighting systems with security systems. A building user enters the building during "off" hours. The security system knows who has entered the building. The building then can turn on lights and HVAC systems in the areas to be used by the person entering.
Smart Windows: For most building users, operable windows are a desirable feature. Smart Windows will know if they are open and will let the building system know. HVAC systems can be automatically turned down in areas with open windows resulting in energy savings. Smart Windows combined with room occupancy sensors will alert building personnel if windows have been accidentally left open in unoccupied areas. Smart Window technology can be combined with natural ventilation schemes to tell building users when opening the windows would be a good idea.

Displacement Ventilation
Displacement ventilation is an innovative concept for the supply of conditioned air and ventilation of buildings. It uses the natural buoyancy of warm air to provide improved ventilation and comfort. First developed for industrial buildings, displacement ventilation now enjoys an increasing percentage of market share for many applications throughout the world. Although relatively new to the United States, displacement ventilation has been in use in the Scandinavian countries since the 1970s, where it is now seen as a proven technology.

In 1998 we completed a pilot demonstration project for the MIT Dept of Architecture, in conjunction with the researchers at MIT who are investigating displacement ventilation for ASHRAE. We now use this concept on many other projects.

In a displacement ventilation system, supply air is introduced to the space at or near the floor level, at a low velocity, at a temperature only slightly below the desired room temperature. The cooler supply air "displaces" the warmer room air, creating a zone of fresh cool air at the occupied level. Heat and contaminants produced by activities in the space rise to the ceiling level where they are exhausted from the space.

Displacement ventilation systems are typically more energy efficient and quieter than conventional overhead systems. They also provide better ventilation efficiency, and thus improve indoor air quality.

Displacement systems are appropriate in spaces such as classrooms and conference rooms with high ventilation requirements. They have also been used with great success in office space.

Displacement Ventilation with Raised Floor
The displacement concept can be combined with raised access flooring to provide additional benefits. The raised floor can be used as an air supply plenum, practically eliminating horizontal distribution ductwork. Modular wiring systems, for power and tel/data can be used in the raised floor.

When fully implemented, this system greatly adds to building flexibility. Modifications are simple and inexpensive. Reconfiguration of building spaces can be done at a fraction of the cost compared to conventional systems.

Raised floor displacement systems can be combined with natural ventilation schemes to take advantage of the thermal storage effects of concrete floors slabs. Cool nighttime air can be brought into the building to drop slab temperatures to the range of 60F. The cooled slabs will absorb room heat throughout the day, reducing building cooling loads, and saving energy. Read the Study on Displacement Ventilation with Raised Floor for the Stata Center.

Chilled Beams
Chilled Beams combine radiant cooling systems with conventional overhead ventilation to reduce energy usage, improve comfort levels, and reduce the architectural impact of ductwork and other mechanical systems. These systems are seen throughout Europe but are rarely considered in the United States, primarily due to engineer's unfamiliarity with these systems. "Chilled beams" have been used with success on several pharmaceutical projects in the USA. See Trox Chilled Beams. See also radiant ceilings and floor slabs.

CFD Modeling of HVAC System Performance
Computational Fluid Dynamics modeling can be used to model airflow in critical spaces. CFD takes air distribution from an art to a science. CFD modeling can potential reduce the size of "overdesigned" systems, by reducing the safety factors typically required in complicated spaces.