Sustainable Building Technical Manual - Etn-presco.net

❑ Perform a pre-occupancy flushout.The building controls can be programmed to initiate the flushing of a building withoutside air prior to occupancy. This reduces indoor pollutants and pre-cools the spacewith night-time air. Running the HVAC system with a higher or continuous supply offresh air is also beneficial during initial occupancy after construction.❑ Consider the use of evaporative cooling equipment.Primarily in dry climates, greater use of outdoor air can translate into improved effectivenessfor direct or indirect evaporative cooling equipment, reducing mechanicalrefrigeration needs. However, proper maintenance is essential to prevent IAQ problemscaused by microbial contamination. (See also Chapter 11, “Renewable Energy.”)Renovation and Retrofit IssuesHVAC system renovations are initiated for a variety of reasons. It is important to considerall of the following issues during this process:❑ Consider chlorofluorocarbon (CFC) changeout.Retrofits offer an opportunity to replace or convert an existing refrigeration system toone that uses an environmentally benign refrigerant.❑ Replace outdated systems or components.Existing HVAC systems may be at the end of their expected life.❑ Address and correct past problems with ventilation and indoor air quality.(See Chapter 13, “Indoor Air Quality,” and Chapter 21, “Operations and Maintenance”).❑ Re-size components to current requirements.Existing system components may be oversized, especially after efficiency improvementsare made to other systems (e.g., lighting reductions). The retrofit process allows systemcomponents to be matched to actual loads with a corresponding efficiency gain.❑ Improve occupant comfort.An assessment of occupant issues related to temperature control and ventilation levelscan lead to renovations that improve comfort levels and productivity.❑ Eliminate code deficiencies.Upgrade components to comply with changes in building codes or comply voluntarilywith current codes.❑ Install new building-control system.Control-system technology is far more advanced than it was several years ago. Modernsystems can be used to manage multiple buildings, alarms, and zones. The purchaseand installation costs of such systems may be justified based on energy savings andbetter indoor air quality.Lighting★ S I G N I F I CA N C E .Artificial lighting constitutes 20 to 30 percent of all energy use in a commercial buildingand approximately one-fifth of all electrical energy use in the United States. 1 Reductionsin energy use can be achieved with natural daylighting, advanced lighting technology,and efficient lighting design.Artificial light has been generally overused in most buildings. Current building codesmandate a maximum lighting power density of 1.5 to 2.5 watts per square foot.Nevertheless, a lighting power density of 0.65 to 1.2 watts per square foot can beachieved while still providing a fully functional, well-lit space. With additional improvementsfrom control systems that reduce usage during periods of non-occupancy, the use