United States Environmental Protection Indoor Environments Division (6609J) Office of air and Radiation EPA-402-S-01 -001F January 2000 Aaencv Energy Cost and IAQ Performance of Ventilation Systems and Controls Project # 6 Meeting Outdoor Air Requirements in Very High Occupant Density Buildings A Study of Auditoriums and Schools ------- Energy Cost and IAQ Performance of Ventilation Systems and Controls Project Report # 6 Meeting Outdoor Air Requirements in Very High Occupant Density Buildings A Study of Auditoriums and Schools Indoor Environments Division Office of Radiation and Indoor Air Office of Air and Radiation United States Environmental Protection Agency Washington, D.C. 20460 January 2000 ------- Energy Cost and IAQ Performance of Ventilation Systems and Controls Project Report # 6 Meeting Outdoor Air Requirements in Very High Occupant Density Buildings A Study of Auditoriums and Schools INTRODUCTION Purpose and Scope of this Report ASHRAE Standard 62-1989 (and the subsequent Standard 62-19991) raised the outdoor air requirements for acceptable indoor air quality for very high occupant density buildings such as schools and auditoriums from its previous level of 5 cfm per occupant to 15 cfm per occupant. Since occupant densities in these buildings can be very high (e.g. 30-150 occupants per 1000 square feet), the absolute increase in outdoor air volumes in these buildings due to ASHRAE Standard 62 is exceptionally large, and outdoor air fractions (proportion of supply air which is outdoor air) rise significantly. Therefore, airflows in these buildings become heavily dominated by indoor air quality requirements rather than by thermal load requirements. This raises questions as to whether VAV systems can effectively meet the ASHRAE requirements under part load conditions. At part load conditions, supply air flows may be less than the required outdoor air flows unless VAV box minimum flow settings are sufficiently high. However, as VAV box minimum flow settings are raised in VAV systems, the operational characteristics of the VAV system approach that of a CV system (see Project Report #3), so that the energy savings of VAV systems over CV systems may be diminished or lost in these buildings. This further suggests that VAV systems in very high occupant density buildings whose design settings are meant to achieve the ASHRAE requirement of 15 cfm per occupant, may not in actuality be meeting that requirement unless their VAV box minimum flow settings are higher than normal practice would provide. In addition, other reports in this project document that the impact on annual energy cost and peak energy load which results from raising outdoor airflow rates from 5 cfm to 20 cfm per occupant tends to be larger for high occupant density office buildings than for average occupant density office buildings (see Project Reports # 4 and #5). In these reports, a high occupant density office building was defined as having only 15 occupants per 1000 square feet. This raises the possibility 1 This project was initiated while ASHRAE Standard 1989 was in effect. However, since the outdoor air flow rates for both the 1989 and 1999 versions are the same, all references to ASHRAE Standard 62 in this report are stated as ASHRAE Standard 62- 1999. Energy Cost and IAQ 1 Report # 6 ------- that the energy impact of raising outdoor airflow rates to 15 cfm per occupant in education buildings, auditoriums, or other very high occupant density structures could be exceptionally high. On the other hand, very high occupant density buildings also have large internal latent loads. Provided that the outdoor air is dry relative to the return air, raising the outdoor air flow rate should reduce latent loads in these buildings and may tend to reduce, rather than increase, cooling energy use. The purpose of this report is to examine these issues in detail. This report quantifies the supply and outdoor airflow requirements, assesses outdoor air fractions required, and establishes appropriate VAV box minimum flow settings for a prototype school and a prototype auditorium in three climates. The report also quantifies the energy cost and peak load impacts of raising outdoor airflow rates from 5 to 15 cfm per occupant in these buildings, and examines the potential of energy recovery for reducing annual energy costs and peak loads. Background This report is part of a larger modeling project that assesses the compatibilities and trade-offs between energy, indoor air, and thermal comfort objectives in the design and operation of HVAC systems for commercial buildings. The report also attempts to shed light on potential strategies for simultaneously achieving superior performance on each objective. It is hoped that this project will contribute to the body of new data needed by professionals and practitioners who design and operate ventilation systems as they attempt to reduce costs and save energy without sacrificing thermal comfort or outdoor air flow performance. The methodology used in this project has been to refine and adapt the DOE-2.1 E building energy analysis computer program for the specific needs of this study, and to generate a detailed database of the energy use, indoor climate, and outdoor air flow rates of various ventilation systems and control strategies. Constant volume (CV) and variable air volume (VAV) systems in different buildings, with different outdoor air control strategies, in alternative climates provide the basis for parametric variations in the database. Seven reports, covering the following topics, describe the findings of this project: Project Report #1: Project objective and detailed description of the modeling methodology and database development Project Report #2: Assessment of energy and outdoor air flow rates in CV and VAV ventilation systems for large office buildings: Project Report #3: Assessment of the distribution of outdoor air and the control of thermal comfort in CV and VAV systems for large office buildings Project Report #4: Energy impacts of increasing outdoor air flow rates from 5 to 20 cfm per occupant in large office buildings Energy Cost and IAQ 2 Report # 6 ------- • Project Report #5: Peak load impacts of increasing outdoor air flow rates from 5 to 20 cfm per occupant in large office buildings • Project Report #6: Potential problems in IAQ and energy performance of HVAC systems when outdoor air flow rates are increased from 5 to 15 cfm per occupant in auditoriums, education, and other buildings with very high occupant density • Project Report #7: The energy cost of protecting indoor environmental quality during energy efficiency projects for office and education buildings DESCRIPTION OF THE BUILDING AND VENTILATION SYSTEMS MODELED A 2 story L shaped education building, and a single story auditorium were modeled in three different climates representing cold (Minneapolis), temperate (Washington, D.C.), and hot/humid (Miami) climate zones. The education building has 6 perimeter zones representing the four compass directions, and two core zones. The auditorium building includes a core zone auditorium and four perimeter zones representing lobby and office spaces. Exhibit 1 shows key building and HVAC system parameters. Exhibit 2 details the occupancy and HVAC equipment operating schedules modeled. A more complete description of the buildings is contained in Project Report #1. A dual duct constant volume (CV) system with temperature reset, and a single duct variable volume (VAV) system with reheat were modeled. Constant volume systems control the thermal conditions in the space by altering the temperature of a constant volume of supply air. VAV systems provide control by altering the supply air volume, while maintaining a constant supply air temperature. For this report, only two basic outdoor air control strategies were employed: constant outdoor air (COA), and temperature-controlled air-side economizer (ECONt). The COA strategy maintains a constant volume of outdoor air irrespective of the supply air volume. The economizer uses additional quantities of outdoor air to provide "free cooling" when the outdoor air temperature is lower than the return air temperature, but is automatically shut off when the outdoor temperature exceeds 65°F to reduce the risk of excess humidity indoors. Below 65°F, the quantity of outdoor air is adjusted so that the desired supply air discharge temperature can be achieved with minimum mechanical cooling. An enthalpy-based economizer is not included for these buildings. A third basic outdoor air control strategy for VAV systems which was assessed in other reports is a fixed outdoor air fraction (FOAF). The FOAF strategy maintains a constant outdoor air fraction (percent outdoor air) irrespective of the supply air volume. The FOAF strategy does not supply the design outdoor air volumes at part load conditions and is therefore not considered a viable strategy (see Project Reports #2 and #3). The VAV (FOAF) system is therefore not modeled for Energy Cost and IAQ 3 Report # 6 ------- these buildings. For the CV system, the FOAF strategy is equivalent to the COA strategy since the supply air volume does not change2. A more detailed description of these HVAC systems and outdoor air control strategies is provided in Project Report #1. APPROACH In this report, the outdoor air quantities for each HVAC system and OA control strategy are determined over the full range of thermal loads. The systems design settings are 5 and 15 cfm of outdoor air per occupant. Annual energy use (KBtu/ft2) is converted to energy cost assuming several different energy price structures for all climates. In the base price structure, the price of electricity were assumed to be $.044 per kilowatt-hour, and $7.89 per kilowatt. Gas, which was used in the space and water heating equipment, was modeled at $0.49 per therm. For comparison purposes, energy costs were also computed for four additional price structures that alter the relative price of gas and electricity, and the electricity demand charge. A detailed description of the derivation of these price structures is shown in Project Report #1. Exhibit 3 presents the utility prices under each price structure. Unless otherwise noted, energy costs refer to costs under the base price structure. The purpose of these pricing variations is to determine how sensitive the conclusions on energy costs are to relative energy prices. Since Minneapolis, Washington, D.C. and Miami are used only to represent different climate conditions, no attempt was made to use the actual energy prices in these individual cities. RESULTS The presentation of results is organized to shed light on the following questions: a. How high must minimum VAV box settings be to accommodate both the ASHRAE Standard 62-1999 outdoor air requirements, and the thermal load requirements of very high occupant density buildings? How do these settings affect the viability and operational integrity of HVAC system controls in these buildings? b. What are the energy cost and peak load impacts of raising the outdoor air requirements from 5 cfm per occupant to 15 cfm per occupant in very high occupant density buildings? c. Given the large outdoor air volumes required in these buildings, what gains may be derived from energy recovery technologies in these buildings? 2 For consistency with other project reports, the CV(FOAF) rather than the CV(COA) designation is used in this report. Energy Cost and IAQ 4 Report # 6 ------- Design Versus Actual Outdoor Air Flows Exhibit 4 presents the percent of occupied hours that specified outdoor air volumes were achieved in the simulations for design outdoor air volumes of 5 and 15 cfm per occupant. For the VAV systems in these runs, the VAV box minimums are set at 30% of peak flow. As expected, CV systems for both the education and assembly building brought in the requisite quantities of outdoor air 100% of the time in all climates at both outdoor air settings of 5 and 15 cfm per occupant. The VAV(COA) system also delivered requisite quantities of outdoor air 100% of the time at a design setting of 5 cfm per occupant, with a VAV box setting of 30%. However, when the outdoor air setting was changed to 15 cfm per occupant, the VAV box minimum setting of 30% was inadequate, and less than 15 cfm per occupant entered the building at part load conditions. This is most notable for the assembly building which has a higher occupant density. For example, for the assembly building in Washington, D.C. and in Minneapolis, the VAV(COA) system delivered less than 10 cfm of outdoor air per occupant 70% and 79% of the time respectively. The problem is less dramatic for Miami because there is a smaller proportion of time spent in part load conditions in the Miami climate. VA V Box Minimum Setting The inadequate outdoor air flow with the VAV(COA) system is not due to the outdoor air flow strategy at the air handler. By definition, the COA strategy insures an adequate supply of outdoor air by increasing the outdoor air fraction at part load conditions. Rather, the problem in this case is with the VAV box minimum settings. Under part load conditions, a VAV box minimum setting of 30% allowed the supply air volume to fall below the outdoor air volume required to meet the 15 cfm per occupant outdoor air requirement. This means that the supply air needed to meet thermal loads at part load is insufficient to meet the outdoor air requirement, even at 100% outdoor air. To solve this problem, simulations were run allowing DOE-2.1 E to automatically establish the VAV box minimum settings necessary to guarantee 15 cfm per occupant of outdoor air under all operating conditions. The minimum settings required are presented in Exhibit 5. The VAV box minimum settings required are substantially higher than 30%. VAV box minimum settings for perimeter zones ranged from 38% - 56% in the education building, and from 39% - 65% in the assembly building. However, in the core zone, minimums ranged from 54%-71 % in the education building, and from 95% -100% for the assembly building. These settings are much higher than are normally provided. Exhibit 6 demonstrates that only properly adjusted (higher) VAV box minimum settings insured that the design outdoor air volume of 15 cfm per occupant is actually met at all operating conditions. Outdoor Air Fraction Energy Cost and IAQ 5 Report # 6 ------- The high VAV box settings suggest that the supply air volumes cannot be reduced substantially in these buildings in response to reduced thermal loads. Exhibit 7 presents the supply volumes and outdoor air fractions which result from HVAC systems in which the VAV box minimum settings are properly adjusted. It is clear that these HVAC systems are easily dominated by the outdoor air requirement rather than the thermal requirement. In this case the VAV system operates very similarly to the CV system. Further, the outdoor air fractions under both design and minimum load conditions are considerably higher than the 10% to 30% normally assumed for office buildings. A design outdoor air fraction of 42%-48% is required for the education building, and 65%-75% for the assembly building. The outdoor air fraction at minimum load is 100% for both buildings. Control of Temperature and Relative Humidity Exhibit 8 presents data showing the proportion of time the average space air temperature for all zones fell within specified temperature bins. This data suggests that all the HVAC systems kept indoor temperatures between 70°F and 79°F virtually all the time. This is true for both the education and assembly building in all three climates. Examination of zone specific temperatures showed a similar pattern in each zone for all systems. All the HVAC systems appear to adequately control indoor temperature. This indicates the systems were adequately sized to meet sensible loads. These systems, however, depend on the cooling system to control relative humidity in the occupied spaces. Given the high occupant densities in these buildings, the internal latent loads are high. Since the required outdoor air quantities are also high, the cooling system may not adequately control relative humidity as it controls temperature. Exhibit 9 shows that, without specific humidity controls, the average zone relative humidity often exceeded 60%, and occasionally exceeded 70%. Because of this, the buildings were also modeled to control relative humidity to 60% by lowering the cooling coil temperature when required to meet the latent load. Annual Energy Cost Exhibit 10 and Exhibit 11 present the annual energy costs for outdoor air settings of 5 and 15 cfm per occupant for the education and assembly building respectively. Exhibit 12 and Exhibit 13 present the absolute and percentage changes in cost. Energy Cost Impact of Raising Outdoor Air Flow Rates from 5 to 15 CFM Per Occupant Project Report # 4 suggests that raising outdoor air flow rates would have only modest impacts on energy use and energy costs for most office buildings, and may, in some buildings, actually reduce rather than raise costs. However, the picture is quite different for very high occupant density buildings such as education and assembly buildings. Raising outdoor air flow rates in these buildings can raise energy costs substantially. Energy Cost and IAQ 6 Report # 6 ------- Exhibit 12 and Exhibit 13 demonstrate that only part of the energy cost increase results from raising the outdoor air design setting from 5 cfm to 15 cfm per occupant. For CV systems, a change in design setting alone raised energy costs by 14% to 31 % for education buildings and by 19% to 50% in auditoriums. For the VAV system, a change in design setting alone raised energy costs by 14% to 19% for education buildings and by 16% to 23% for assembly buildings. However, as noted above, for VAV systems, changing the outdoor air setting alone, without changing the VAV box setting, did not provide 15 cfm of outdoor air under part load conditions. Therefore, these costs do not reflect the full costs of raising the outdoor air flow rates. When the VAV box minimum flow settings are also adjusted to insure adequate outdoor airflow, the energy costs of raising outdoor air flow rates to15 cfm per occupant for VAV systems were 15%-32% for education buildings, and 25% - 67% for auditoriums. Finally, because controlling temperature in both the CV and VAV systems did not adequately control the relative humidity in the occupied space when outdoor airflows were 15 cfm per occupant, adding humidity control to 60% relative humidity raised the energy cost impact to between 17% and 39% for CV systems in education buildings, and between 26% and 58% for CV systems in auditoriums. The energy cost impact for VAV systems was 15% to 35% in education buildings, and 35% to 81 % in auditoriums. These increases are much larger than is normally assumed. These increases reflect utility prices under the base price structure used in this study. However, Exhibit 14 and Exhibit 15 demonstrate that the energy cost increase is very large under all the price structures analyzed in this project (Exhibit 3). Climate Effects The energy cost impacts of raising outdoor airflow rates from 5 cfm to 15 cfm per occupant were greater in the cold and temperate climates of Minneapolis and Washington, D.C., than in the hot and humid climate of Miami. This conclusion also runs contrary to popular belief. The reason is that while hot humid climates experience the largest absolute increment in cooling costs, heating costs rose dramatically in temperate and cold climates when outdoor air flow rates are raised to 15 cfm per occupant, but rose only slightly in the hot and humid climate. As a result, the annual energy cost increase in both absolute and percentage terms was much greater for the cold and temperate climate than it was in the hot and humid climate. This is true for all five utility price structures. Heating System Effects of CV and VA V Systems The CV and VAV systems modeled have significantly different relative heating cost impacts of increased outdoor air. In both systems the OA requirement was the same. In the CV systems, heating costs rose substantially when outdoor air flow rates were increased from 5 to 15 cfm per occupant because of the need to heat cold outside air during cold weather. The effect on heating energy for VAV systems, however, was not the same. Since the VAV system has zone reheat, heating does not occur until after the air passes through the cooling coil. Since the discharge Energy Cost and IAQ 7 Report # 6 ------- temperature of the supply air from the cooling coil is approximately the same at 5 cfm as it is at 15 cfm per occupant, there would ordinarily be no substantial impact on heating energy. In office (lower occupant density) buildings, the outdoor air fraction is usually too low to force the mixed air temperature below 45°F so that preheat was not normally necessary. But for the very high occupant density buildings modeled here, the outdoor air fraction is very high. This means that in very cold weather, preheat coils in the VAV system are activated to heat the air before it enters the cooling coil to avoid freezing the coil. The large volumes of outdoor air during cold weather may reduce cooling energy costs in VAV systems, as would an economizer, but at a heating cost penalty, which in this case is a preheat penalty 3. The large jump in heating costs in the VAV system occured when the VAV box minimum settings are adjusted to raise the outdoor air volumes at part load conditions. This raised the outdoor air fraction and resulted in colder mixed air temperature on cold winter days. This created a larger outdoor air heating burden at the preheat coil. In very high occupant density buildings with VAV systems, most of the increase in heating was the additional preheat coil load, while heating coil loads were only moderately affected. In contrast, CV systems in the same buildings had much more profound central heating coil loads, and less burden on the preheat coil. Economizers At 5 cfm of outdoor air per occupant, the economizer reduced cooling energy costs by approximately $.05 per square foot in the Minneapolis and Washington, D.C. climates, by raising outdoor air volumes when the outdoor air was cooler than the return air. Economizers have little or no advantage in Miami4. However, when the outdoor air volume was raised to 15 cfm per occupant in these very high occupant density buildings, much of the economizer advantage was already accounted for by these high outdoor air flow rates. In fact, for VAV systems, the economizers never became operational because additional quantities of outdoor air were not needed to reduce cooling costs. The VAV(COA) and the VAV(COA)(ECON) systems were therefore operationally identical. Integrity of VA V Systems At 5 cfm of outdoor air per occupant, the VAV system had a significant energy advantage over the CV systems because of reduced fan energy and cooling energy costs for both the education and assembly building. At 15 cfm per occupant, with appropriate adjustments of the VAV box and control of relative humidity at 60%, the VAV system had similar advantages in the education building. However, when occupant densities rose again, as in the auditorium, the advantages of 3 See Project Report # 5 for discussion of this effect in office buildings 4 For a more detailed explanation of economizer advantages, see Project Report # 2. Energy Cost and IAQ 8 Report # 6 ------- the VAV system disappeared. In fact, in the auditorium, the VAV system cost more to operate than the CV system. Both the cooling cost and the heating cost were higher for the VAV system than for the CV system in the auditorium. The air flows of the VAV system were operating similar to the air flows of the CV system, but the CV system, with its dual duct and temperature reset capability is more efficient than the single duct VAV system with zone reheat under these conditions. This suggests that VAV systems may not be appropriate in auditoriums, or similar buildings where the occupant densities are extraordinarily high. Peak Load Impacts of Raising Outdoor Air Flow Rates to 15 CFM Per Occupant Exhibit 16-19 present peak load data for both 5 and 15 cfm of outdoor air per occupant. Changes in peak loads shed light on whether or not existing systems sized to provide 5 cfm of outdoor air per occupant are likely to have sufficient capacity to also provide 15 cfm per occupant without retrofit. In addition, peak loads at 15 cfm per occupant provide some measure of the potential for downsizing equipment in energy conservation retrofits. Peak Cooling Load Peak cooling loads for CV systems were increased by 20% - 26% in the education building and by 30% - 32% in the auditorium. For the VAV system, peak cooling loads were increased 20%- 26% in the education building, and by 21 %- 28% in the auditorium. These increases are substantial. It suggests that buildings sized for 5 cfm per occupant will probably not be capable of achieving 15 cfm per occupant with the same cooling equipment, and that energy retrofits of existing buildings which are also being redesigned to meet ASHRAE 62-1999 may be severely limited in how much downsizing can actually take place. Peak Heating Coil Loads Peak heating loads for CV systems in Minneapolis and Washington, D.C. increased by 12% - 30% in the education building, and by 3% - 22% in the auditorium. For VAV systems in Minneapolis and Washington, D.C., peak heating loads increased less than 10% for the education building, and by 9%-22% for the auditorium. In Miami, the peak heating loads were negligible at 5 cfm of outdoor air per occupant for both the education building and the auditorium. However, at 15 cfm per occupant, peak heating coil loads rose to 480 - 520 k BTU/hr. These results suggest raising outdoor airflow rates to 15 cfm per occupancy results in only modest increases on the main heating coil, and these increases could probably be accommodated with existing systems designed for 5 cfm per occupant. However, in hot and humid climates such as Miami, the peak heating coil loads at 15 cfm per occupant, while small, may be more than current systems are designed to handle. Peak Preheat Coil Loads Energy Cost and IAQ 9 Report # 6 ------- At 5 cfm of outdoor air per occupant, no preheat coil loads were experienced for any CV system in either the education or assembly building in any climate modeled. When outdoor air volumes were increased to 15 cfm per occupant, preheat coil requirements appeared in Minneapolis and Washington, D.C. They were highest in Minneapolis and were greater in the auditorium than in the education building. In the auditorium in Minneapolis, peak preheat coil loads exceeded 1000 kBTU/hr. No preheat requirements were experienced for CV systems in Miami either at 5 or 15 cfm per occupant. A similar pattern is presented for VAV systems. In Minneapolis, peak preheat coil loads went from 246 to 1282 kBTU/hr in education buildings, and from 330 to 919 kBTU/hr in auditoriums when outdoor air volumes were increased from 5 to 15 cfm per occupant. Smaller increases were experienced in Washington, D.C. and Miami. Many systems have little or no preheat coil loads at 5 cfm per occupant. The emergence of a preheat load means that existing systems designed at 5 cfm per occupant may experience significant damage from coil freezing if run to accommodate 15 cfm per occupant without adding preheat coil capacity. It also means that new systems must include preheat coils to accommodate 15 cfm of outdoor air per occupant. The problem is especially prevalent in cold climates (e.g., Minneapolis), but the emergence of even a small preheat coil requirement could portend freezing damage if it is not available. Potential for Energy Recovery Technology The substantial increase in energy cost associated with raising outdoor air flow to meet ASHRAE Standard 62-1999 for education and assembly buildings constitutes a significant potential savings for efficient energy recovery technology. The extent to which such a potential could be realized was not modeled because DOE-2.1 E is extremely limited in its ability to model energy recovery systems. However, some literature suggests that available energy recovery technology can significantly reduce or eliminate the increased energy cost and further improve the potential to downsize equipment in these buildings (Rengarajan, et al. 1996; Shirey et al. 1996) SUMMARY & CONCLUSIONS VAV systems derive much of their attractiveness for energy conservation by their ability to save fan energy during part load conditions. However, in buildings with high occupant densities, such as the schools and auditoriums, the high outdoor air volumes required by ASHRAE Standard 62-1999 places a floor on the extent to which VAV systems can pinch down during part load, so that VAV systems in these buildings operate more like CV systems when meeting the outdoor air requirements of ASHRAE Standard 62-1999. The VAV box minimum settings must necessarily be much higher than are typically used for office environments in order to provide sufficient outdoor air. This, in part, explains the higher energy cost associated with raising the outdoor air setting from 5 cfm to 15 cfm per occupant in these buildings. Economizers may not have much advantage in high occupant density buildings because much of the advantage of economizers is already accounted Energy Cost and IAQ 10 Report # 6 ------- for by the higher outdoor air flow rates. In fact, the economizer for the VAV system never became operational when 15 cfm of outdoor air was maintained in the school and education building. In most office buildings, when the cooling plant is sized to meet the sensible load, the latent load is most often also satisfied. However, in schools and auditoriums, when the cooling plan twas sized to meet the sensible load at 15 cfm per occupant, the latent load was most often not accommodated, raising the relative humidity often above 60% and occasionally above 70% in the occupied spaces. Unlike office buildings, when outdoor airflow rates were raised from 5 to 20 cfm per occupant in the education and assembly buildings, energy costs increased substantially. The HVAC energy cost increase of raising outdoor air flow rates was 17% to 39% for CV systems in education buildings, and 26% to 58% for CV systems in auditoriums. The HVAC energy cost impact for VAV systems was 15% to 35% in education buildings, and 35% to 81% in auditoriums. These increases were partly due to raising the outdoor air flow settings, partly due to changing the VAV box minimum settings to insure adequate outdoor air flow, and partly due to the need to control humidity to below 60%. Peak cooling loads increased 20%-32% when raising outdoor airflow rates from 5-15 cfm per occupant, while only modest increases in the main heating coil were experienced. However, peak preheat coil loads were also substantially increased. Many systems have little or no preheat coil loads at 5 cfm per occupant. Thus, existing systems designed for 5 cfm of outdoor air per occupant may not be capable of maintaining thermal comfort during heavy loads. In addition, the emergence of a preheat load means that existing systems designed at 5 cfm per occupant may experience significant damage from coil freezing if run at 15 cfm per occupant without adding preheat coil capacity. The higher peak loads also suggest that meeting ASHRAE 62-1999 during an energy retrofit places severe limitations on the extent to which cooling equipment can be downsized. The increased annual energy cost and the effect on equipment capacity make the use of energy recovery systems potentially very attractive to high occupant density building, and further research into this potential would be useful. Energy Cost and IAQ 11 Report # 6 ------- BIBLIOGRAPHY ASHRAE , 1999, ASHRAE Standard 62-1999: Ventilation for Acceptable Indoor Air Quality. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta. Cowan, J., 1986?, "Implications of Providing Required Outside Air Quantities in Office Buildings", ASHRAE Transactions. V. Pt. , Atlanta. Curtis, R., Birdsall, B., Buhl, W., Erdem, E., Eto, J., Hirsch, J., Olson, K., and Winkelmann, F., 1984, DOE-2 Building Energy Use Analysis Program. Lawrence Berkeley Laboratory, LBL-18046. Eto, J., and Meyer, C., 1988, "The HVAC Costs of Fresh Air Ventilation in Office Buildings", ASHRAE Transactions. V. 94, Pt.2. Eto, J., 1990, "The HVAC Costs of Increased Fresh Air Ventilation Rates in Office Buildings, Part 2", from Proc. of Indoor Air 90: The Fifth International Conference on Indoor Air Quality and Climate, Toronto, Canada. Levenhagen, J., 1992, "Control Systems to Comply with ASHRAE Standard 62-1999", ASHRAE Journal. Atlanta, September. Mutammara, A., and Hittle, D., 1990, "Energy Effects of Various Control Strategies for Variable Air Volume Systems", ASHRAE Transactions. V. 96, Pt. 1, Atlanta. Rengarajan, K.; Shirey, D. B. Ill, and Raustad, R.1996. Cost-effective HVAC technologies to meet ASHRAE Standard 62-1999 in hot and humid climates. ASHRAE Transactions, V. 102(1). Shirey D.B. and Rengarajan, K. 1996. Impacts of ASHRAE Standard 62-1999 on small florida offices. ASHRAE Transactions, V. 102(1). Sauer, H., and Howell, R., 1992, "Estimating the Indoor Air Quality and Energy Performance of VAV Systems", ASHRAE Journal. Atlanta, July. Energy Cost and IAQ 12 Report # 6 ------- Exhibit 1: Characteristics of the Base Buildings Modeled in this Study Education Assembly Building Characteristics shape L-shaped square zones/floor 6 5 floor area (ft2) 50,600 19,600 number of floors 2 1 floor height (ft) 15 30 wall construction concrete block concrete block net window area (%) 34% 7% window U-value (Btu/hr ft2 °F) 0.59 0.59 window shading coefficient 0.6 0.6 wall R-value (hr ft2 °F/Btu) R-8 R-8 roof R-value (hr ft2 °F/Btu) R-12 R-12 perimeter/core ratio* 1.0 0.6 infiltration rate (ach) 0.25 0.25 Occupancy number of occupants 1,518 588 occupant density (occup/1000ft2) 30 60 11 VAC air distribution system central (CVorVAV) central (CVorVAV) heating and DHW central gas boiler - 80% efficiency central gas boiler - 80% efficiency cooling chiller - 4 COP w/cooling tower chiller - 4 COP w/cooling tower * Ratio of perimeter to core floor area, where perimeter space is up to 15 ft. from the exterior walls Energy Cost and IAQ 13 Report # 6 ------- xhibit 2: Occupant & Operating Schedules for Office, Education, and Assembly Buildings Office Building Education Building Assembly Occupancy HVAC Occupancy HVAC Occupancy HVAC Hour Mo n-Fri WE/ Hoi Mon Tue- Fri WE/ Hoi Mon- Fri Sat. Sun/ Hoi Mon- Fri Sat Sun/ Hoi Mon- Fri WE/ Hoi Mon-Fri WE/ Hoi 1-5 0% 0% night night night 0% 0% 0% night night night 0% 0% night night 6 0% 0% St Up night night 0% 0% 0% St Up St Up night 0% 0% night night 7 0% 0% St Up St Up night 0% 0% 0% St Up St Up night 0% 0% night night 8 25% 0% day day night 10% 0% 0% day day night 0% 0% night night 9 75% 0% day day night 100% 10% 0% day day night 10% 10% St Up St Up 10-12 95% 0% day day night 100% 10% 0% day day night 10% 10% day day 13 75% 0% day day night 100% 10% 0% day day night 50% 75% day day 14-15 95% 0% day day night 100% 0% 0% day day night 50% 75% day day 16 95% 0% day day night 50% 0% 0% day day night 50% 75% day day 17 75% 0% day day night 50% 0% 0% day day night 50% 75% day day 18 50% 0% day day night 50% 0% 0% day day night 50% 75% day day 19 25% 0% night night night 15% 0% 0% day night night 100% 100% day day 20-21 10% 0% night night night 20% 0% 0% day night night 100% 100% day day 22 10% 0% night night night 10% 0% 0% day night night 100% 100% day day 23-24 0% 0% night night night 0% 0% 0% night night night 50% 75% day day St Up = startup; day = full operation; night = operating with night temperature set back of 10°F. Energy Cost and IAQ 14 Report # 6 ------- Exhibit 3 Utility Rate Structures Modeled Rate Class Rate Structure Rate Structures Gas Rate Electric Rate Electric Demand Gas Rate Electric Rate Electric Demand Ratche t Clause Base Average Average Average $0,490 $0,044 $7,890 No Option 1 Low High Average $0,330 $0,063 $7,890 No Option 2 High Low Average $0,650 $0,025 $7,890 No Option 3 Average Average High $0,490 $0,044 $11,710 No Option 4 Average Average Low $0,490 $0,044 $4,070 No Energy Cost and IAQ 15 Report # 6 ------- Exhibit 4 Percent of Occupied Hours Air Flows are Achieved for Education Buildings HVAC System Design OA Flow Rate Minneapolis, MN 5 cf m 15 cf m Washington, DC 5 cfm 15 cf m Miami, FL 5 cfm 15 cfm CV (FOAF) <5 6-10 11-15 16-19 >20 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0% 0.0% CV (FOAF) EconT <5 6-10 11-15 16-19 >20 67.5% 0.0% 18.9% 0.0% 4.0% 0.0% 2.3% 93.4% 7.3% 6.6% 73.3% 0.0% 12.4% 0.0% 3.9% 0.0% 2.9% 93.4% 7.4% 6.6% 92.6% 0.0% 0.4% 0.0% 0.8% 0.0% 0.7% 94.6% 5.4% 5.4% VAV (COA) <5 6-10 11-15 16-19 >20 100.0% 0.0% 0.0% 0.0% 0.0% 76.8% 0.0% 23.2% 0.0% 0.0% 100.0% 0.0% 0.0% 46.2% 0.0% 23.7% 0.0% 30.0% 0.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 12.8% 0.0% 87.2% 0.0% 0.0% VAV (COA) EconT <5 6-10 11-15 16-19 >20 44.8% 0.0% 34.7% 0.0% 19.1% 76.8% 1.2% 23.0% 0.2% 0.2% 50.5% 0.0% 39.8% 46.2% 9.3% 23.7% 0.4% 30.0% 0.0% 0.0% 92.6% 0.0% 0.4% 0.0% 4.4% 12.8% 1.9% 86.4% 0.8% 0.8% Energy Cost and IAQ 16 Report # 6 ------- Exhibit 4 (cont.) Percent of Occupied Hours Air Flows are Achieved for Assembly Buildings HVAC System Design OA Flow Rate Minneapolis, MN 5 cf m 15 cf m Washington, DC 5 cf m 15 cf m Miami, FL 5 cfm 15 cf m CV (FOAF) <5 6-10 11-15 16-19 >20 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0% 0.0% CV (FOAF) EconT <5 6-10 11-15 16-19 >20 61.8% 0.0% 30.1% 0.0% 3.6% 0.0% 1.6% 97.1% 3.0% 2.9% 76.8% 0.0% 13.1% 0.0% 3.3% 0.0% 2.1% 95.3% 4.7% 4.7% 91.2% 0.0% 0.9% 0.0% 1.4% 0.0% 1.3% 94.7% 5.2% 5.3% VAV (COA) <5 6-10 11-15 16-19 >20 100.0% 0.0% 0.0% 78.5% 0.0% 17.8% 0.0% 3.7% 0.0% 0.0% 100.0% 0.0% 0.0% 69.8% 0.0% 22.5% 0.0% 7.8% 0.0% 0.0% 100.0% 0.0% 0.0% 8.5% 0.0% 37.0% 0.0% 54.5% 0.0% 0.0% VAV (COA) EconT <5 6-10 11-15 16-19 >20 68.4% 0.0% 29.2% 78.5% 2.4% 17.8% 0.0% 3.7% 0.0% 0.0% 69.9% 0.0% 26.4% 69.8% 3.6% 22.5% 0.1% 7.8% 0.0% 0.0% 91.1% 0.0% 3.8% 8.5% 4.8% 37.0% 0.4% 54.5% 0.0% 0.0% Energy Cost and IAQ 17 Report # 6 ------- Exhibit 5 VAV Box Minimum Settings Necessary to Guarantee 15 cfm/person During All Occupied Hours (Percent of Peak Zone Supply Air Flow) Building Type Minneapolis, MN Washington, DC Miami, FL Zone Education Core 71.0% 68.4% 53.7% East 39.4% 45.1% 37.8% North 53.6% 55.5% 43.8% West 48.5% 52.2% 43.4% South 47.1% 51.1% 42.6% Assembly Core 100.0% 100.0% 95.0% East 38.9% 65.1% 46.5% North 40.7% 41.8% 62.7% West 42.0% 57.4% 52.7% South 43.8% 52.3% 54.1% Energy Cost and IAQ 18 Report # 6 ------- Exhibit 6 Percent of Occupied Hours Outdoor Air Flow Rates are Achieved with and without VAV Box Adjustments at a Design Setting of 15 cfm/person Building Minneapolis, MN Washington DC Miami, FL HVAC System Unadjusted Adjusted Unadjusted Adjusted Unadjusted Adjusted Education VAV (COA) <5 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 6-10 0.0% 0.0% 46.2% 0.0% 0.0% 0.0% 11-15 76.8% 0.0% 23.7% 0.0% 12.8% 0.0% 16-19 23.2% 100.0% 30.0% 100.0% 87.2% 100.0% >20 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% VAV (COA) EconT <5 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 6-10 0.0% 0.0% 46.2% 0.0% 0.0% 0.0% 11-15 76.8% 0.0% 23.7% 0.0% 12.8% 0.0% 16-19 23.0% 99.4% 30.0% 100.0% 86.4% 98.9% >20 0.2% 0.6% 0.0% 0.0% 0.8% 1.1% Assembly VAV (COA) <5 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 6-10 78.5% 0.0% 69.8% 0.0% 8.5% 0.0% 11-15 17.8% 0.0% 22.5% 0.0% 37.0% 0.0% 16-19 3.7% 100.0% 7.8% 100.0% 54.5% 100.0% >20 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% VAV (COA) EconT <5 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 6-10 78.5% 0.0% 69.8% 0.0% 8.5% 0.0% 11-15 17.8% 0.0% 22.5% 0.0% 37.0% 0.0% 16-19 3.7% 100.0% 7.8% 100.0% 54.5% 100.0% >20 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% Energy Cost and IAQ 19 Report # 6 ------- Exhibit 7 Supply Volume and Outdoor Air Fractions for 5 and 15 cfm Outddor Air per person at Design and Minimum Load Conditions Building Minneapolis, MN Washing ton, DC Miami, FL Supply Volume OA Fraction Supply Volume OA Fraction Supply Volume OA Fraction HVAC System 5 cfm 15 cfm 5 cfm 15 cfm 5 cfm 15 cfm 5 cfm 15 cfm 5 cfm 15 cfm 5 cfm 15 cfm Education CV (FOAF) Design Load 53684 53684 0.140 0.419 45123 45123 0.161 0.484 50944 50944 0.143 0.428 Minimum Load 53684 53684 0.140 0.419 45123 45123 0.161 0.484 50944 50944 0.143 0.428 VAV (COA) Design Load 53684 53684 0.140 0.419 45123 45123 0.161 0.484 50944 50944 0.143 0.428 Minimum Load 16105 22478 0.465 1.000 13537 21823 0.537 1.000 15283 21823 0.476 1.000 Assembly CV (FOAF) Design Load 26185 26185 0.216 0.647 23415 23415 0.234 0.703 22496 22496 0.244 0.732 Minimum Load 26185 26185 0.216 0.647 23415 23415 0.234 0.703 22496 22496 0.244 0.732 VAV (COA) Design Load 26185 26185 0.216 0.647 22100 22100 0.248 0.745 22496 22496 0.244 0.732 Minimum Load 7856 16955 0.719 1.000 6630 16461 0.828 1.000 6749 16461 0.813 1.000 Energy Cost and IAQ Report # 6 ------- Exhibit 8 Percent of Occupied Hours with Specified Indoor Air Temperatures for Education Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL Temperature 5 cfm 15 cfm 5 cfm 15 cfm 5 cfm 15 cfm CV (FOAF) 70 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 71-74 88.4% 89.7% 78.0% 78.8% 4.8% 6.3% 75-79 11.6% 10.3% 22.0% 21.2% 95.2% 93.7% 79 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% CV (FOAF) EconT 70 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 71-74 88.4% 89.7% 78.0% 78.8% 4.8% 6.4% 75-79 11.6% 10.3% 22.0% 21.2% 95.2% 93.6% 79 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% VAV (COA) 70 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 71-74 76.8% 76.9% 58.8% 59.0% 1.8% 2.1% 75-79 23.2% 23.1% 41.2% 41.0% 98.2% 97.9% 79 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% VAV (COA) EconT 70 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 71-74 77.0% 76.9% 59.1% 59.0% 2.0% 2.1% 75-79 23.0% 23.1% 40.9% 41.0% 98.0% 97.9% 79 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% Energy Cost and IAQ 21 Report # 6 ------- Exhibit 8 (cont.) Percent of Occupied Hours with Specified Indoor Air Temperatures for Assembly Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL Temperature 5 cfm 15 cfm 5 cfm 15 cfm 5 cfm 15 cfm CV (FOAF) 70 2.9% 2.9% 2.5% 2.6% 0.0% 0.0% 71-74 57.8% 66.5% 41.6% 51.6% 0.5% 2.1% 75-79 39.4% 30.6% 55.9% 45.8% 99.1% 97.5% 79 0.0% 0.0% 0.0% 0.0% 0.3% 0.3% CV (FOAF) EconT 70 2.9% 2.9% 2.5% 2.6% 0.0% 0.0% 71-74 58.0% 66.6% 41.8% 51.7% 0.5% 2.2% 75-79 39.1% 30.6% 55.6% 45.7% 99.1% 97.5% 79 0.0% 0.0% 0.0% 0.0% 0.3% 0.3% VAV (COA) 70 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 71-74 68.7% 69.3% 49.2% 49.6% 0.6% 0.7% 75-79 31.3% 30.7% 50.8% 50.4% 99.2% 97.6% 79 0.0% 0.0% 0.0% 0.0% 0.2% 1.7% VAV (COA) EconT 70 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 71-74 68.9% 69.3% 49.4% 49.6% 0.7% 0.7% 75-79 31.1% 30.7% 50.6% 50.4% 99.1% 97.6% 79 0.0% 0.0% 0.0% 0.0% 0.2% 1.7% Energy Cost and IAQ 22 Report # 6 ------- Exhibit 9 Percent of Occupied Hours with Specified Indoor Relative Humidity for Education Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL Relative Humidity 5 cfm 15 cfm 5 cfm 15 cfm 5 cfm 15 cfm CV(FOAF) <20% 11.7% 19.3% 7.4% 12.5% 0.2% 0.4% 21-29% 11.8% 19.5% 7.8% 12.3% 1.0% 1.2% 30-50% 34.3% 43.1% 30.6% 40.6% 27.3% 21.0% 51-60% 23.7% 13.8% 28.6% 24.2% 52.7% 51.4% 61-70% 13.7% 3.9% 17.1% 9.9% 18.3% 25.2% >70% 4.9% 0.3% 8.5% 0.6% 0.5% 0.9% CV (FOAF) EconT <20% 12.1% 19.3% 8.0% 12.7% 0.5% 0.4% 21-29% 13.1% 20.0% 9.6% 12.7% 1.6% 1.5% 30-50% 36.2% 43.0% 32.7% 40.0% 27.3% 20.9% 51-60% 21.5% 13.5% 26.8% 24.2% 51.9% 50.9% 61-70% 12.5% 3.9% 15.5% 9.6% 18.2% 25.3% >70% 4.6% 0.3% 7.5% 0.8% 0.5% 0.9% VAV (COA) <20% 12.7% 18.5% 8.3% 11.5% 0.1% 0.4% 21-29% 11.2% 15.6% 7.5% 9.2% 0.9% 1.3% 30-50% 26.9% 41.2% 24.1% 35.6% 14.8% 16.7% 51-60% 21.7% 14.7% 22.5% 24.3% 43.2% 38.5% 61-70% 17.4% 7.7% 20.4% 14.6% 32.7% 35.4% >70% 10.1% 2.3% 17.3% 4.9% 8.4% 7.6% VAV (COA) EconT <20% 14.3% 18.5% 9.8% 11.5% 0.4% 0.4% 21-29% 12.4% 15.6% 8.9% 9.2% 1.2% 1.3% 30-50% 33.6% 41.2% 29.3% 35.6% 15.6% 16.7% 51-60% 22.4% 14.7% 23.0% 24.3% 42.8% 38.5% 61-70% 12.5% 7.6% 18.5% 14.6% 32.2% 35.4% >70% 4.8% 2.3% 10.6% 4.9% 7.8% 7.6% Energy Cost and IAQ 23 Report # 6 ------- Exhibit 9 (cont.) Percent of Occupied Hours with Specified Indoor Relative Humidity for Assembly Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL Relative Humidity 5 cfm 15 cfm 5 cfm 15 cfm 5 cfm 15 cfm CV(FOAF) <20% 9.1% 19.6% 5.8% 10.8% 0.1% 0.1% 21-29% 9.2% 19.4% 5.7% 15.1% 0.8% 1.2% 30-50% 32.1% 34.8% 24.6% 31.8% 16.3% 18.0% 51-60% 25.1% 15.9% 24.8% 19.7% 47.0% 52.8% 61-70% 18.6% 8.9% 28.4% 20.5% 35.6% 27.5% >70% 5.9% 1.4% 10.8% 2.1% 0.3% 0.2% CV (FOAF) EconT <20% 9.3% 19.6% 6.1% 11.1% 0.2% 0.2% 21-29% 9.4% 19.4% 6.5% 15.4% 1.2% 1.3% 30-50% 34.3% 35.0% 27.8% 31.6% 17.3% 18.3% 51-60% 24.3% 15.6% 25.2% 19.3% 45.9% 52.3% 61-70% 16.9% 8.9% 25.5% 20.3% 35.1% 27.7% >70% 5.7% 1.5% 8.9% 2.2% 0.3% 0.2% VAV (COA) <20% 10.1% 14.1% 7.0% 7.9% 0.1% 0.1% 21-29% 11.6% 14.2% 9.0% 11.0% 0.8% 1.1% 30-50% 31.6% 36.2% 25.4% 30.7% 11.0% 16.3% 51-60% 17.1% 17.5% 18.7% 22.0% 40.1% 51.2% 61-70% 16.2% 11.4% 23.0% 21.3% 44.1% 30.3% >70% 13.4% 6.6% 17.0% 7.1% 3.9% 0.9% VAV (COA) EconT <20% 10.2% 14.1% 7.1% 7.9% 0.1% 0.1% 21-29% 12.1% 14.2% 9.9% 11.0% 1.0% 1.1% 30-50% 34.7% 36.2% 27.2% 30.7% 12.4% 16.3% 51-60% 17.0% 17.5% 19.4% 22.0% 39.9% 51.2% 61-70% 15.2% 11.4% 22.3% 21.3% 42.8% 30.3% >70% 10.8% 6.6% 14.1% 7.1% 3.9% 0.9% Energy Cost and IAQ 24 Report # 6 ------- Exhibit 10 Annual HVAC Energy Costs for Education Buildings at Alternative Outdoor Air Settings ($/sf) HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person person VAV Box Min 30% Adjusted VAV Box person VAV Box Min 30% Adjusted VAV Box person VAV Box Min 30% Adjusted VAV Box End Use No RH Control RH Control No RH Control RH Control No RH Control RH Control CV (FOAF) Fan 0.28 0.28 0.28 0.23 0.23 0.23 0.26 0.26 0.25 Cooling 0.41 0.47 0.52 0.45 0.53 0.55 0.71 0.84 0.88 Heating 0.23 0.44 0.46 0.08 0.18 0.20 0.00 0.00 0.01 Total 0.92 1.19 1.25 0.76 0.95 0.97 0.97 1.10 1.14 CV (FOAF) EconT Fan 0.28 0.28 0.28 0.23 0.23 0.23 0.26 0.26 0.25 Cooling 0.38 0.45 0.50 0.42 0.51 0.53 0.70 0.84 0.88 Heating 0.24 0.44 0.46 0.08 0.19 0.20 0.00 0.00 0.01 Total 0.89 1.17 1.24 0.73 0.93 0.96 0.96 1.10 1.14 VAV (COA) Fan 0.17 0.17 0.18 0.17 0.16 0.16 0.17 0.16 0.20 0.20 0.20 0.17 Cooling 0.39 0.41 0.42 0.43 0.43 0.49 0.50 0.52 0.64 0.75 0.76 0.79 Heating 0.32 0.42 0.51 0.52 0.14 0.17 0.25 0.26 0.00 0.00 0.00 0.01 Total 0.87 1.01 1.11 1.12 0.73 0.83 0.92 0.93 0.84 0.95 0.96 0.97 VAV (COA) EconT Fan 0.17 0.17 0.18 0.17 0.16 0.16 0.17 0.16 0.20 0.20 0.20 0.17 Cooling 0.35 0.41 0.42 0.43 0.40 0.49 0.50 0.51 0.64 0.75 0.76 0.79 Heating 0.32 0.42 0.51 0.52 0.14 0.17 0.25 0.26 0.00 0.00 0.00 0.01 Total 0.84 1.01 1.11 1.12 0.70 0.83 0.92 0.93 0.84 0.95 0.96 0.97 Energy Cost and IAQ Report # 6 ------- Exhibit 11 Annual HVAC Energy Costs for Assembly Buildings at Alternative Outdoor Air Settings ($/sf) HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person person VAV Box Min 30% Adjusted VAV Box person VAV Box Min 30% Adjusted VAV Box person VAV Box Min 30% Adjusted VAV Box End Use No RH Control RH Control No RH Control RH Control No RH Control RH Control CV (FOAF) Fan 0.41 0.41 0.42 0.36 0.36 0.39 0.34 0.34 0.34 Cooling 0.65 0.77 0.86 0.71 0.83 0.92 1.25 1.56 1.66 Heating 0.49 1.08 1.09 0.17 0.50 0.52 0.00 0.00 0.01 Total 1.55 2.26 2.37 1.24 1.70 1.83 1.60 1.90 2.01 CV (FOAF) EconT Fan 0.41 0.41 0.42 0.36 0.36 0.39 0.34 0.34 0.34 Cooling 0.58 0.73 0.82 0.64 0.79 0.89 1.23 1.55 1.66 Heating 0.50 1.08 1.10 0.18 0.51 0.53 0.00 0.00 0.01 Total 1.49 2.23 2.35 1.18 1.66 1.81 1.57 1.89 2.01 VAV (COA) Fan 0.24 0.27 0.30 0.29 0.23 0.25 0.29 0.28 0.29 0.30 0.33 0.30 Cooling 0.52 0.58 0.68 0.82 0.63 0.74 0.80 0.97 1.10 1.32 1.41 1.55 Heating 0.58 0.76 1.22 1.27 0.23 0.28 0.61 0.67 0.00 0.00 0.01 0.03 Total 1.34 1.62 2.20 2.38 1.10 1.27 1.71 1.92 1.40 1.62 1.74 1.88 VAV (COA) EconT Fan 0.24 0.27 0.30 0.29 0.23 0.25 0.29 0.28 0.29 0.30 0.33 0.30 Cooling 0.49 0.58 0.68 0.82 0.61 0.74 0.80 0.97 1.09 1.32 1.41 1.55 Heating 0.58 0.76 1.22 1.27 0.23 0.28 0.61 0.67 0.00 0.00 0.01 0.03 Total 1.31 1.62 2.20 2.38 1.07 1.27 1.71 1.92 1.39 1.62 1.74 1.88 Energy Cost and IAQ Report # 6 ------- Exhibit 12 Change in HVAC Energy Costs for Education Buildings Due to Increased Outdoor Air Flow Rates from 5 to 15 cfm/person ($/sf) HVAC System Minneapolis, MN Washington, DC Miami, FL End Use 5 cfm/ person ($/sf) Difference 15-5 cfm/person 5 cfm/ person ($/sf) Difference 15-5 cfm/person 5 cfm/ person Difference 15-5 cfm/person VAV Box Min 30% Adjusted VAV Box VAV Box Min 30% Adjusted VAV Box VAV Box Min 30% Adjusted VAV Box ($/sf) (%) ($/sf) (%) ($/sf) (%) ($/sf) (%) ($/sf) ($/sf) (%) ($/sf) (%) CV (FOAF) Fan Cooling Heating Total 0.28 0.41 0.06 14% 0.23 0.21 90% 0.92 0.27 29% 0.23 0.45 0.08 18% 0.08 0.11 135% 0.76 0.19 25% 0.26 0.71 0.13 19% 0.00 0.97 0.13 14% CV (FOAF) EconT Fan Cooling Heating Total 0.28 0.38 0.07 18% 0.24 0.21 87% 0.89 0.27 31% 0.23 0.42 0.09 23% 0.08 0.10 130% 0.73 0.20 27% 0.26 0.70 0.14 19% 0.00 0.96 0.14 14% VAV (COA) Fan Cooling Heating Total 0.17 0.01 5% 0.39 0.03 8% 0.04 9% 0.32 0.10 32% 0.19 60% 0.87 0.13 15% 0.24 27% 0.16 0.01 6% 0.43 0.06 15% 0.07 17% 0.14 0.03 25% 0.11 82% 0.73 0.10 14% 0.19 27% 0.20 0.64 0.11 17% 0.11 18% 0.00 0.84 0.11 14% 0.12 15% VAV (COA) EconT Fan Cooling Heating Total 0.17 0.01 5% 0.35 0.06 18% 0.07 19% 0.32 0.10 31% 0.19 59% 0.84 0.16 19% 0.27 32% 0.16 0.01 6% 0.40 0.09 22% 0.10 25% 0.14 0.03 24% 0.11 81% 0.70 0.12 18% 0.22 31% 0.20 0.64 0.11 18% 0.12 18% 0.00 0.84 0.12 14% 0.13 15% Energy Cost and IAQ Report # 6 ------- Exhibit 13 Change in HVAC Energy Costs for Assembly Buildings Due to Increased Outdoor Air Flow Rates from 5 to 15 cfm/person ($/sf) Building Minneapolis, MN Washington, DC Miami, FL Configuration 5 cfm/ person Difference 15-5 cfm/person 5 cfm/ person Difference 15-5 cfm/person 5 cfm/ person Difference 15-5 cfm/person VAV Box Min 30% Adjusted VAV Box VAV Box Min 30% Adjusted VAV Box VAV Box Min 30% Adjusted VAV Box End Use ($/sf) ($/sf) (%) ($/sf) (%) ($/sf) ($/sf) (%) ($/sf) (%) ($/sf) ($/sf) (%) ($/sf) (%) CV(FOAF) Fan 0.41 0.36 0.34 Cooling 0.65 0.12 18% 0.71 0.12 17% 1.25 0.30 24% Heating 0.49 0.59 121% 0.17 0.33 197% 0.00 Total 1.55 0.71 46% 1.24 0.45 36% 1.60 0.31 19% CV (FOAF) EconT Fan 0.41 0.36 0.34 Cooling 0.58 0.15 26% 0.64 0.15 24% 1.23 0.32 26% Heating 0.50 0.58 118% 0.18 0.33 184% 0.00 Total 1.49 0.74 50% 1.18 0.48 41% 1.57 0.32 20% VAV (COA) Fan 0.24 0.03 14% 0.06 24% 0.23 0.02 9% 0.06 26% 0.29 0.01 2% 0.03 11% Cooling 0.52 0.07 13% 0.16 30% 0.63 0.10 17% 0.17 28% 1.10 0.21 19% 0.30 28% Heating 0.58 0.18 31% 0.64 111 % 0.23 0.05 20% 0.38 162% 0.00 0.01 807% Total 1.34 0.28 21% 0.86 64% 1.10 0.17 16% 0.61 56% 1.40 0.22 16% 0.35 25% VAV (COA) EconT Fan 0.24 0.03 14% 0.06 24% 0.23 0.02 9% 0.06 26% 0.29 0.01 2% 0.03 11% Cooling 0.49 0.09 19% 0.18 37% 0.61 0.13 21% 0.20 33% 1.09 0.22 20% 0.31 29% Heating 0.58 0.18 31% 0.64 111 % 0.23 0.05 20% 0.38 162% 0.00 0.01 786% Total 1.31 0.30 23% 0.88 67% 1.07 0.20 18% 0.64 60% 1.39 0.23 16% 0.36 26% Energy Cost and IAQ Report # 6 ------- Exhibit 14 Utility Price Sensitivity of Annual HVAC Energy Costs for Education Buildings ($/sf) HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person person w/RH Difference (15-5) person w/RH Difference (15-5) person w/RH Difference (15-5) Utility Option Control ($/sf) (%) Control ($/sf) (%) Control ($/sf) (%) CV (FOAF) Base Price 0.92 1.25 0.33 36% 0.76 0.97 0.22 28% 0.97 1.14 0.17 17% Option 1 1.00 1.27 0.27 27% 0.89 1.08 0.19 21% 1.22 1.44 0.21 17% Option 2 0.84 1.24 0.39 47% 0.63 0.87 0.24 38% 0.72 0.84 0.13 17% Option 3 1.08 1.45 0.37 34% 0.91 1.16 0.25 27% 1.16 1.35 0.20 17% Option 4 0.76 1.05 0.29 38% 0.60 0.78 0.18 30% 0.78 0.93 0.14 18% CV (FOAF) EconT Base Price 0.89 1.24 0.35 39% 0.73 0.96 0.23 32% 0.96 1.14 0.18 18% Option 1 0.95 1.24 0.29 30% 0.84 1.06 0.21 25% 1.21 1.43 0.22 18% Option 2 0.83 1.23 0.40 49% 0.61 0.87 0.26 41% 0.71 0.84 0.13 18% Option 3 1.05 1.44 0.39 37% 0.89 1.15 0.27 30% 1.14 1.35 0.20 18% Option 4 0.73 1.04 0.30 42% 0.57 0.77 0.20 35% 0.77 0.92 0.15 19% VAV (COA) Base Price 0.87 1.12 0.25 28% 0.73 0.93 0.21 28% 0.84 0.97 0.13 15% Option 1 0.88 1.07 0.18 21% 0.80 0.98 0.18 22% 1.05 1.20 0.15 15% Option 2 0.86 1.18 0.31 36% 0.65 0.89 0.24 36% 0.64 0.74 0.10 16% Option 3 1.01 1.28 0.27 26% 0.88 1.11 0.23 27% 1.02 1.17 0.16 15% Option 4 0.73 0.96 0.23 31% 0.58 0.75 0.18 31% 0.66 0.76 0.10 15% VAV (COA) EconT Base Price 0.84 1.12 0.28 33% 0.70 0.93 0.23 33% 0.84 0.97 0.13 16% Option 1 0.84 1.07 0.23 27% 0.77 0.98 0.21 28% 1.04 1.20 0.16 15% Option 2 0.85 1.18 0.33 38% 0.64 0.89 0.25 39% 0.63 0.74 0.11 17% Option 3 0.98 1.28 0.30 30% 0.85 1.11 0.26 30% 1.01 1.17 0.16 16% Option 4 0.70 0.96 0.26 37% 0.55 0.75 0.20 37% 0.66 0.76 0.10 16% Exhibit 15 Utility Price Sensitivity of Annual HVAC Energy Costs for Assembly Buildings ($/sf) Energy Cost and IAQ Report # 6 ------- HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person person w/RH Difference (15-5) person w/RH Difference (15-5) person w/RH Difference (15-5) Utility Option Control ($/sf) (%) Control ($/sf) I (%) Control ($/sf) (%) CV (FOAF) Base Price 1.55 2.37 0.82 53% 1.24 1.83 0.59 47% 1.60 2.01 0.42 26% Option 1 1.64 2.28 0.63 39% 1.45 1.95 0.49 34% 2.05 2.56 0.51 25% Option 2 1.46 2.46 1.01 69% 1.03 1.71 0.68 66% 1.14 1.46 0.33 29% Option 3 1.78 2.69 0.91 51% 1.46 2.14 0.68 47% 1.85 2.37 0.51 28% Option 4 1.32 2.05 0.73 55% 1.02 1.52 0.49 48% 1.34 1.66 0.32 24% CV (FOAF) EconT Base Price 1.49 2.35 0.86 58% 1.18 1.81 0.63 53% 1.57 2.01 0.43 27% Option 1 1.55 2.23 0.69 44% 1.36 1.91 0.55 40% 2.02 2.55 0.53 26% Option 2 1.43 2.46 1.03 72% 1.00 1.71 0.71 71% 1.13 1.46 0.34 30% Option 3 1.72 2.67 0.95 55% 1.40 2.13 0.72 52% 1.83 2.36 0.53 29% Option 4 1.26 2.02 0.77 61% 0.96 1.50 0.54 56% 1.32 1.65 0.34 26% VAV (COA) Base Price 1.34 2.38 1.04 78% 1.10 1.92 0.82 75% 1.40 1.88 0.48 35% Option 1 1.31 2.20 0.89 68% 1.21 1.98 0.77 64% 1.79 2.39 0.60 34% Option 2 1.36 2.56 1.20 88% 0.98 1.85 0.87 88% 1.01 1.37 0.37 36% Option 3 1.52 2.65 1.13 74% 1.30 2.21 0.90 69% 1.64 2.20 0.56 34% Option 4 1.15 2.11 0.96 83% 0.89 1.63 0.74 83% 1.16 1.57 0.41 35% VAV (COA) EconT Base Price 1.31 2.38 1.07 81% 1.07 1.92 0.85 79% 1.39 1.88 0.49 36% Option 1 1.28 2.20 0.93 73% 1.17 1.98 0.81 69% 1.77 2.39 0.61 35% Option 2 1.35 2.56 1.21 90% 0.97 1.85 0.88 91% 1.00 1.37 0.37 37% Option 3 1.50 2.65 1.16 77% 1.28 2.21 0.93 72% 1.63 2.20 0.57 35% Option 4 1.13 2.11 0.98 87% 0.87 1.63 0.77 89% 1.15 1.57 0.42 36% Exhibit 16 Energy Cost and IAQ Report # 6 ------- HVAC System Peak Coil Loads for Education Buildings at Alternative Outdoor Air Settings (kBTU/Hr) HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person person VAV Box Min 30% Adjusted VAV Box person VAV Box Min 30% Adjusted VAV Box person VAV Box Min 30% Adjusted VAV Box Coil No RH Control RH Control No RH Control RH Control No RH Control RH Control CV (FOAF) Cooling 2068 2478 2747 2071 2594 2633 2409 3030 2912 Heating 2459 3197 3197 1818 2118 2118 17 536 598 Preheat 0 683 683 0 183 183 0 0 0 CV (FOAF) EconT Cooling 2068 2478 2747 2071 2594 2633 2409 3030 2912 Heating 2609 3197 3197 1884 2118 2118 17 536 580 Preheat 0 683 683 0 183 183 0 0 0 VAV (COA) Cooling 1841 2211 2211 2210 1951 2453 2439 2421 2213 2785 2742 2760 Heating 2819 2819 2820 2820 1935 1981 2027 2027 391 464 668 669 Preheat 246 1344 1528 1528 90 521 840 840 0 140 200 200 VAV (COA) EconT Cooling 1841 2211 2211 2210 1951 2453 2439 2421 2213 2785 2742 2760 Heating 2819 2819 2820 2820 1935 1981 2027 2027 397 464 668 670 Preheat 246 1344 1528 1528 90 521 840 840 0 140 200 200 Energy Cost and IAQ 31 Report # 6 ------- Exhibit 17 HVAC System Peak Coil Loads for Assembly Buildings at Alternative Outdoor Air Settings (kBTU/Hr) HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person 5 cfm/ 15 cfm/person person VAV Box Min 30% Adjusted VAV Box person VAV Box Min 30% Adjusted VAV Box person VAV Box Min 30% Adjusted VAV Box Coil No RH Control RH Control No RH Control RH Control No RH Control RH Control CV (FOAF) Cooling 1193 1568 1720 1144 1491 1679 1394 1838 2005 Heating 1449 1517 1517 1009 1227 1227 61 541 542 Preheat 0 1097 1097 0 577 577 0 0 0 CV (FOAF) EconT Cooling 1193 1568 1720 1157 1505 1679 1394 1838 2005 Heating 1476 1517 1517 1153 1303 1227 63 541 542 Preheat 0 1097 1097 0 577 577 0 0 0 VAV (COA) Cooling 958 1161 1230 1511 1067 1360 1342 1599 1229 1575 1577 1738 Heating 1134 1151 1240 1240 822 868 999 999 96 109 390 391 Preheat 330 1090 1249 1249 224 409 777 777 0 84 151 151 VAV (COA) EconT Cooling 958 1161 1230 1511 1067 1360 1342 1599 1229 1575 1577 1738 Heating 1134 1151 1240 1240 822 868 999 999 99 109 390 391 Preheat 330 1090 1249 1249 224 409 777 777 0 84 151 151 Energy Cost and IAQ Report # 6 ------- Exhibit 18 Change in HVAC System Peak Coil Loads for Education Buildings Due to Increased Outdoor Air Flow Rates from 5 to 15 cfm/person HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ Difference 15-5 cfm/person 5 cfm/ Difference 15-5 cfm/person 5 cfm/ Difference 15-5 cfm/person person perso perso (kBTU/ Hr) VAV Box Min 30% Adjusted VAV Box n VAV Box Min 30% Adjusted VAV Box n VAV Box Min 30% Adjusted VAV Box Coil (kBtu/ Hr) (%) (kBtu/ Hr) (%) (kBtu/ Hr) (kBtu/ Hr) (%) (kBtu/ Hr) (%) (kBtu/ Hr) (kBtu/ Hr) (%) (kBtu/ Hr) (%) CV (FOAF) Cooling 2068 410 20% 2071 524 25% 2409 622 26% Heating 2459 737 30% 1818 300 17% 17 519 3118% Preheat 0 683 Increas e 0 183 Increas e 0 CV (FOAF) EconT Cooling 2068 410 20% 2071 524 25% 2409 622 26% Heating 2609 588 23% 1884 234 12% 17 520 3124% Preheat 0 683 Increas e 0 183 Increas e 0 VAV (COA) Cooling 1841 370 20% 370 20% 1951 502 26% 488 25% 2213 571 26% 529 24% Heating 2819 1 1935 46 2% 93 5% 391 73 19% 277 71% Preheat 246 1098 447% 1282 521 % 90 431 478% 750 832% 0 140 Increase 200 Increase VAV (COA) EconT Cooling 1841 370 20% 370 20% 1951 502 26% 488 25% 2213 571 26% 529 24% Heating 2819 1 1935 46 2% 93 5% 397 67 17% 271 68% Preheat 246 1098 447% 1282 521 % 90 431 478% 750 832% 0 140 Increase 200 Increase Energy Cost and IAQ Report # 6 ------- Exhibit 19 Change in HVAC System Peak Coil Loads for Assembly Buildings Due to Increased Outdoor Air Flow Rates from 5 to 15 cfm/person HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ Difference 15-5 cfm/person 5 cfm/ Difference 15-5 cfm/person 5 cfm/ Difference 15-5 cfm/person perso perso perso n VAV Box Min 30% Adjusted VAV Box n VAV Box Min 30% Adjusted VAV Box n VAV Box Min 30% Adjusted VAV Box Coil (kBtu/ Hr) (kBtu/ Hr) (%) (kBtu/ Hr) (%) (kBtu / Hr) (kBtu/ Hr) (%) (kBtu/ Hr) (%) (kBtu / Hr) (kBtu/ Hr) (%) (kBtu/ Hr) (%) CV(FOAF) Cooling 1193 375 31% 1144 347 30% 1394 444 32% Heating 1449 68 5% 1009 218 22% 61 480 791% Preheat 0 1097 Increase 0 577 Increase 0 CV (FOAF) EconT Cooling 1193 375 31% 1157 348 30% 1394 444 32% Heating 1476 41 3% 1153 149 13% 63 478 758% Preheat 0 1097 Increase 0 577 Increase 0 VAV (COA) Cooling 958 203 21% 271 28% 1067 293 27% 275 26% 1229 346 28% 349 28% Heating 1134 17 1% 106 9% 822 46 6% 177 22% 96 13 13% 294 306% Preheat 330 760 230% 919 279% 224 185 83% 553 247% 0 84 Increase 151 Increas e VAV (COA) EconT Cooling 958 203 21% 271 28% 1067 293 27% 275 26% 1229 346 28% 349 28% Heating 1134 17 1% 106 9% 822 46 6% 177 22% 99 10 10% 291 293% Preheat 330 760 230% 919 279% 224 185 83% 553 247% 0 84 Increase 151 Increas e Energy Cost and IAQ Report # 6 ------- Exhibit 20 Annual HVAC Energy Cost Impacts with and without Sensible Heat Recovery for Education Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ perso n 15 cfm/person w/RH Control 5 cfm/ person 15 cfm/person w/RH Control 5 cfm/ person 15 cfm/person w/RH Control without Heat Recovery with Heat Recovery without Heat Recovery with Heat Recovery without Heat Recovery with Heat Recovery End Use ($/sf) ($/sf) (%) ($/sf) (%) ($/sf) ($/sf) (%) ($/sf) (%) ($/sf) ($/sf) (%) ($/sf) (%) CV(FOAF) Fan 0.28 0.28 0.28 0.23 0.23 0.23 0.26 0.25 -3% 0.25 -3% Cooling 0.41 0.52 27% 0.52 27% 0.45 0.55 22% 0.55 22% 0.71 0.88 24% 0.88 24% Heating 0.23 0.46 95% 0.44 90% 0.08 0.20 149% 0.19 148% 0.00 0.01 79273% 0.01 77670% Total 0.92 1.25 36% 1.24 35% 0.76 0.97 28% 0.97 28% 0.97 1.14 17% 1.14 17% CV (FOAF) EconT Fan 0.28 0.28 0.28 0.23 0.23 0.23 0.26 0.25 -3% 0.25 -3% Cooling 0.38 0.50 32% 0.50 32% 0.42 0.53 27% 0.53 27% 0.70 0.88 25% 0.88 25% Heating 0.24 0.46 95% 0.45 90% 0.08 0.20 150% 0.20 148% 0.00 0.01 87489% 0.01 85877% Total 0.89 1.24 39% 1.22 37% 0.73 0.96 32% 0.96 32% 0.96 1.14 18% 1.14 18% VAV (COA) Fan 0.17 0.17 0.17 0.16 0.16 0.16 0.20 0.17 -12% 0.17 -12% Cooling 0.39 0.43 12% 0.43 12% 0.43 0.52 20% 0.52 20% 0.64 0.79 22% 0.79 22% Heating 0.32 0.52 63% 0.42 31% 0.14 0.26 92% 0.23 70% 0.00 0.01 1036% 0.01 1024% Total 0.87 1.12 28% 1.02 16% 0.73 0.93 28% 0.90 24% 0.84 0.97 15% 0.97 15% VAV (COA) EconT Fan 0.17 0.17 0.17 0.16 0.16 0.16 0.20 0.17 -12% 0.17 -12% Cooling 0.35 0.43 22% 0.43 22% 0.40 0.51 28% 0.51 28% 0.64 0.79 23% 0.79 23% Heating 0.32 0.52 62% 0.42 30% 0.14 0.26 90% 0.23 69% 0.00 0.01 978% 0.01 967% Total 0.84 1.12 33% 1.02 21% 0.70 0.93 33% 0.90 29% 0.84 0.97 16% 0.97 16% Energy Cost and IAQ Report # 6 ------- Exhibit 21 Annual HVAC Energy Cost Impacts with and without Sensible Heat Recovery for Assembly Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ perso n 15 cfm/person w/RH Control 5 cfm/ person 15 cfm/person w/RH Control 5 cfm/ person 15 cfm/person w/RH Control without Heat Recovery with Heat Recovery without Heat Recovery with Heat Recovery without Heat Recovery with Heat Recovery End Use ($/sf) ($/sf) (%) ($/sf) (%) ($/sf) ($/sf) (%) ($/sf) (%) ($/sf) ($/sf) (%) ($/sf) (%) CV(FOAF) Fan 0.41 0.42 2% 0.42 2% 0.36 0.39 8% 0.39 8% 0.34 0.34 0.34 Cooling 0.65 0.86 31% 0.86 31% 0.71 0.92 30% 0.92 30% 1.25 1.66 33% 1.66 33% Heating 0.49 1.09 124% 0.89 83% 0.17 0.52 207% 0.47 175% 0.00 0.01 2016% 0.01 1991% Total 1.55 2.37 53% 2.17 40% 1.24 1.83 47% 1.78 43% 1.60 2.01 26% 2.01 26% CV (FOAF) EconT Fan 0.41 0.42 2% 0.42 2% 0.36 0.39 8% 0.39 8% 0.34 0.34 0.34 Cooling 0.58 0.82 41% 0.82 41% 0.64 0.89 39% 0.89 39% 1.23 1.66 34% 1.66 34% Heating 0.50 1.10 123% 0.90 82% 0.18 0.53 199% 0.48 169% 0.00 0.01 801% 0.01 792% Total 1.49 2.35 58% 2.14 44% 1.18 1.81 53% 1.76 49% 1.57 2.01 27% 2.01 27% VAV (COA) Fan 0.24 0.29 22% 0.29 22% 0.23 0.28 20% 0.28 20% 0.29 0.30 0.30 Cooling 0.52 0.82 57% 0.82 57% 0.63 0.97 54% 0.97 54% 1.10 1.55 41% 1.55 41% Heating 0.58 1.27 120% 0.90 55% 0.23 0.67 187% 0.54 129% 0.00 0.03 2102% 0.03 2034% Total 1.34 2.38 78% 2.00 50% 1.10 1.92 75% 1.78 63% 1.40 1.88 35% 1.88 35% VAV (COA) EconT Fan 0.24 0.29 22% 0.29 22% 0.23 0.28 20% 0.28 20% 0.29 0.30 0.30 Cooling 0.49 0.82 66% 0.82 66% 0.61 0.97 60% 0.97 60% 1.09 1.55 42% 1.55 42% Heating 0.58 1.27 120% 0.90 54% 0.23 0.67 186% 0.54 129% 0.00 0.03 2047% 0.03 1984% Total 1.31 2.38 81% 2.00 53% 1.07 1.92 79% 1.78 66% 1.39 1.88 36% 1.88 35% Energy Cost and IAQ Report # 6 ------- Exhibit 22 Effect of Sensible Heat Recovery on HVAC System Peak Coil Loads for Education Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person w/RH Control 5 cfm/ 15 cfm/person w/RH Control 5 cfm/ 15 cfm/person w/RH Control perso person person n without with without with without with Heat Recovery Heat Recovery (kBtu/ Heat Recovery Heat Recovery (kBtu/ Heat Recovery Heat Recovery Coil (kBtu/ (kBtu/ (%) (kBtu/ (%) Hr) (kBtu/ (%) (kBtu/ (%) Hr) (kBtu/ (%) (kBtu/ (%) Hr) Hr) Hr) Hr) Hr) Hr) Hr) CV(FOAF) Cooling 2068 2747 33% 2747 33% 2071 2633 27% 2633 27% 2409 2912 21% 2912 21% Heating 2459 3197 30% 3197 30% 1818 2118 17% 2118 17% 17 598 3488% 594 3468% Preheat 0 683 Increas e 0 0 183 Increas e 0 0 0 0 CV (FOAF) EconT Cooling 2068 2747 33% 2747 33% 2071 2633 27% 2633 27% 2409 2912 21% 2912 21% Heating 2609 3197 23% 3197 23% 1884 2118 12% 2118 12% 17 580 3387% 577 3366% Preheat 0 683 Increas e 0 0 183 Increas e 77 Increas e 0 0 0 VAV (COA) Cooling 1841 2210 20% 2210 20% 1951 2421 24% 2421 24% 2213 2760 25% 2760 25% Heating 2819 2820 2820 1935 2027 5% 2027 5% 391 669 71% 669 71% Preheat 246 1528 521% 12 -95% 90 840 832% 3 -96% 0 200 Increas e 0 VAV (COA) EconT Cooling 1841 2210 20% 2210 20% 1951 2421 24% 2421 24% 2213 2760 25% 2760 25% Heating 2819 2820 2820 1935 2027 5% 2027 5% 397 670 69% 670 69% Preheat 246 1528 521% 12 -95% 90 840 832% 3 -96% 0 200 Increas e 0 Energy Cost and IAQ Report # 6 ------- Exhibit 23 Effect of Sensible Heat Recovery on HVAC System Peak Coil Loads for Assembly Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person w/RH Control 5 cfm/ 15 cfm/person w/RH Control 5 cfm/ 15 cfm/person w/RH Control perso person person n without with without with without with Heat Recovery Heat Recovery (kBtu/ Heat Recovery Heat Recovery (kBtu/ Heat Recovery Heat Recovery Coil (kBtu/ (kBtu/ (%) (kBtu/ (%) Hr) (kBtu/ (%) (kBtu/ (%) Hr) (kBtu/ (%) (kBtu/ (%) Hr) Hr) Hr) Hr) Hr) Hr) Hr) CV(FOAF) Cooling 1193 1720 44% 1720 44% 1144 1679 47% 1679 47% 1394 2005 44% 2005 44% Heating 1449 1517 5% 1517 5% 1009 1227 22% 1227 22% 61 542 793% 541 790% Preheat 0 1097 Increas e 0 0 577 Increas e 0 0 0 0 CV (FOAF) EconT Cooling 1193 1720 44% 1720 44% 1157 1679 45% 1679 45% 1394 2005 44% 2005 44% Heating 1476 1517 3% 1517 3% 1153 1227 6% 1227 6% 63 542 760% 541 758% Preheat 0 1097 Increas e 44 Increase 0 577 Increas e 38 Increas e 0 0 0 VAV (COA) Cooling 958 1511 58% 1511 58% 1067 1599 50% 1599 50% 1229 1738 41% 1738 41% Heating 1134 1240 9% 1240 9% 822 999 22% 999 22% 96 391 306% 385 301% Preheat 330 1249 279% 71 -79% 224 777 247% 4 -98% 0 151 Increas e 0 VAV (COA) EconT Cooling 958 1511 58% 1511 58% 1067 1599 50% 1599 50% 1229 1738 41% 1738 41% Heating 1134 1240 9% 1240 9% 822 999 22% 999 22% 99 391 294% 386 289% Preheat 330 1249 279% 71 -79% 224 777 247% 4 -98% 0 151 Increas e 0 Energy Cost and IAQ Report # 6 ------- Exhibit 24 Annual HVAC Energy Cost Impacts with and without Desiccant Dehumidification for Education Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ perso n ($/sf) 15 cfm/person w/RH Control 5 cfm/ person ($/sf) 15 cfm/person w/RH Control 5 cfm/ person ($/sf) 15 cfm/person w/RH Control without Desiccant Dehumidificatio n with Desiccant Dehumidificatio n without Desiccant Dehumidification with Desiccant Dehumidificatio n without Desiccant Dehumidification with Desiccant Dehumidification End Use ($/sf) (%) ($/sf) (%) ($/sf) (%) ($/sf) (%) ($/sf) (%) ($/sf) (%) CV(FOAF) Fan 0.28 0.28 0.34 22% 0.23 0.23 0.28 21% 0.26 0.25 -3% 0.32 25% Cooling 0.41 0.52 27% 0.50 21% 0.45 0.55 22% 0.51 14% 0.71 0.88 24% 0.78 10% Heating 0.23 0.44 90% 0.51 118% 0.08 0.19 148% 0.34 329% 0.00 0.01 77670% 0.14 1996414 % Total 0.92 1.24 35% 1.34 46% 0.76 0.97 28% 1.13 49% 0.97 1.14 17% 1.25 29% CV (FOAF) EconT Fan 0.28 0.28 0.34 21% 0.23 0.23 0.28 20% 0.26 0.25 -3% 0.32 25% Cooling 0.38 0.50 32% 0.48 27% 0.42 0.53 27% 0.50 20% 0.70 0.88 25% 0.78 12% Heating 0.24 0.45 90% 0.50 111 % 0.08 0.20 148% 0.31 291% 0.00 0.01 85877% 0.19 2664107 % Total 0.89 1.22 37% 1.32 48% 0.73 0.96 32% 1.09 50% 0.96 1.14 18% 1.29 35% VAV (COA) Fan 0.17 0.17 0.22 33% 0.16 0.16 0.20 23% 0.20 0.17 -12% 0.25 25% Cooling 0.39 0.43 12% 0.40 5% 0.43 0.52 20% 0.47 10% 0.64 0.79 22% 0.70 10% Heating 0.32 0.42 31% 0.47 47% 0.14 0.23 70% 0.35 155% 0.00 0.01 1024% 0.17 22722% Total 0.87 1.02 16% 1.10 26% 0.73 0.90 24% 1.02 40% 0.84 0.97 15% 1.12 33% VAV (COA) EconT Fan 0.17 0.17 0.22 32% 0.16 0.16 0.20 22% 0.20 0.17 -12% 0.25 25% Cooling 0.35 0.43 22% 0.41 17% 0.40 0.51 28% 0.49 20% 0.64 0.79 23% 0.71 11% Heating 0.32 0.42 30% 0.46 43% 0.14 0.23 69% 0.33 139% 0.00 0.01 967% 0.16 19936% Total 0.84 1.02 21% 1.10 30% 0.70 0.90 29% 1.01 44% 0.84 0.97 16% 1.11 33% Energy Cost and IAQ Report # 6 ------- Exhibit 25 Annual HVAC Energy Cost Impacts with and without Desiccant Dehumidification for Assembly Buildings HVAC System Minneapolis, MN Washington, DC Miami, FL 5 cfm/ 15 cfm/person w/RH Control 5 cfm/ 15 cfm/person w/RH Control 5 cfm/ 15 cfm/person w/RH Control perso person person n without with without with without with Desiccant Desiccant Desiccant Desiccant Desiccant Desiccant Dehumidificatio Dehumidificatio ($/sf) Dehumidification Dehumidificatio ($/sf) Dehumidification Dehumidification ($/sf) n n n End Use ($/sf) (%) ($/sf) (%) ($/sf) (%) ($/sf) (%) ($/sf) (%) ($/sf) | (%) CV(FOAF) Fan 0.41 0.42 2% 0.51 24% 0.36 0.39 8% 0.44 22% 0.34 0.34 0.45 33% Cooling 0.65 0.86 31% 0.82 25% 0.71 0.92 30% 0.85 20% 1.25 1.66 33% 1.47 17% Heating 0.49 0.89 83% 1.10 125% 0.17 0.47 175% 0.84 393% 0.00 0.01 1991% 0.03 7181% Total 1.55 2.17 40% 2.42 56% 1.24 1.78 43% 2.13 72% 1.60 2.01 26% 1.95 22% CV (FOAF) EconT Fan 0.41 0.42 2% 0.51 24% 0.36 0.39 8% 0.44 22% 0.34 0.34 0.45 33% Cooling 0.58 0.82 41% 0.78 35% 0.64 0.89 39% 0.83 29% 1.23 1.66 34% 1.46 18% Heating 0.50 0.90 82% 1.09 119% 0.18 0.48 169% 0.81 353% 0.00 0.01 792% 0.03 3020% Total 1.49 2.14 44% 2.38 60% 1.18 1.76 49% 2.07 75% 1.57 2.01 27% 1.94 24% VAV (COA) Fan 0.24 0.29 22% 0.38 60% 0.23 0.28 20% 0.36 53% 0.29 0.30 0.40 36% Cooling 0.52 0.82 57% 0.75 45% 0.63 0.97 54% 0.86 36% 1.10 1.55 41% 1.35 22% Heating 0.58 0.90 55% 1.07 84% 0.23 0.54 129% 0.86 267% 0.00 0.03 2034% 0.17 11521% Total 1.34 2.00 50% 2.20 65% 1.10 1.78 63% 2.07 89% 1.40 1.88 35% 1.92 38% VAV (COA) EconT Fan 0.24 0.29 22% 0.38 60% 0.23 0.28 20% 0.35 52% 0.29 0.30 0.40 37% Cooling 0.49 0.82 66% 0.76 54% 0.61 0.97 60% 0.87 44% 1.09 1.55 42% 1.35 23% Heating 0.58 0.90 54% 1.06 82% 0.23 0.54 129% 0.83 254% 0.00 0.03 1984% 0.17 11218% Total 1.31 2.00 53% 2.20 67% 1.07 1.78 66% 2.05 91% 1.39 1.88 35% 1.92 38% Energy Cost and IAQ 40 Report # 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