BUILDING OUTCOME EVALUATION AND ENVIROMENTAL MONITORING VIKING TERRACE: WORTHINGTON, MINNESOTA

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1 BUILDING EVALUATION AND ENVIRONMENTAL MONITORING REPORT CENTER FOR SUSTAINABLE BUILDING RESEARCH, UMN This report is a summary of building testing and environmental monitoring conducted at the Viking Terrace Apartments from 2007 to Authors: William Weber (CSBR, UMN), Stephen Klossner, Marilou Cheple (formerly of Cold Climate Housing Center, UMN), and John Carmody (CSBR, UMN) Field Team Building Testing: Marilou Cheple (Cold Climate Housing UMN), Steve Klossner (ACT, evaluation leader), Rachel Hilvert (CSBR), Rolf Jacobson (CSBR), Richard Stone (UMN Extension), and William Weber (CSBR) Building Monitoring: William Weber (CSBR), Rachel Hilvert (CSBR), Steve Klossner (ACT), Marilou Cheple (Cold Climate Housing UMN) and Southwest Minnesota Housing Partnership staff and management team PURPOSE The purpose of this study is to characterize the indoor environment of the apartments at Viking Terrace post renovation. The assessment occurred in two phases, first a building evaluation to examine the physical characteristics of the building; and second a building monitoring phase to track and observe the indoor environment. The phase one assessment was benchmarked against national and state building standards as well as measures set out by the Green Communities Criteria. The second phase was benchmarked against the parameters of human comfort, health, and building science guidelines for durability in cold climate construction. BACKGROUND The Viking Terrace Apartments project is a rehab of 60 units of housing originally built in The rehab of the apartments was a pilot project for the Minnesota Green Communities and utilized Enterprise s Green Communities Criteria (version 1) to set goals for the project for water and energy efficiency. The criteria were also used to establish targets for unit ventilation and followed prescriptive measures to improve air quality through material and finish selection. The Viking Terrace complex consists of three buildings with a total of 60 units (1440: 12 units, 1450: 24 units and 1460: 24 units). The rehab was carried out in phases beginning in March of 2006 with the 1440 building and concluding in March 2007 with the completion of

2 BUILDING EVALUATION The following testing was completed on the 1450 building at Viking Terrace in March The goal of the testing was to assess the quality and condition of the rehabbed apartments with regard to stated goals of the project and best practices. o Air handler tightness: Air handling systems were tested with a duct blaster for total system tightness. o Ventilation: 1. Air handler flow 2. Single bathroom fan flow (on high speed) 3. Kitchen exhaust flow 4. Combinations of the above o Building shell testing: The building shell was tested with a calibrated blower door with total shell leakage quantified at cubic feet per minute (CFM) per square foot of conditioned space. o Unit tightness: A sampling of units was tested for air leakage to the outside and air leakage between units to quantify the leakage between units as a percent of their total leakage. o Building pressures within individual units: Pressures were measured in individual units with reference to the outside with kitchen fans, bathroom fans, and air handler in operation. Interior doors were closed if the rooms were positively pressured and open if the rooms were neutral or negatively pressured relative to the main space. BUILDING EVALUATOIN SUMMARY Table 1 contains a summary of findings and comparative design standards for the building evaluation testing. The primary building testing was conducted on March 26 & 27, 2007, after renovations were complete but before building re-occupancy. 2

3 Viking Terrace Building Evaluation Summary Ventilation System Before Renovation After Renovation Comparison to Design Standard Fresh Air Supply none (bldg leakage only) 2-Bedroom unit avg=21 cfm; 3- Bedroom unit avg= 27 cfm 70% (ASHRAE 62.2) Kitchen Exhaust Yes (flow rate unknown) 80 cfm (160 cfm fans specified) 100 cfm (ASHRAE 62.2) Bath Exhaust Yes (flow rate unknown) 66 cfm (80 cfm fans specified) 50 cfm (ASHRAE 62.2) Building Envelop Leakage Very High (draft conditions) Pa Pa (MN SF) Duct Leakage unknown 25 Pa 6 cfm/sf (EPA) Duct Return Air Flow unknown 345 cfm within +/- 10% of mfg spec Notes: cfm = cubic feet per minute, Pa = Pascal, ASHRAE = American Society of Heating Refrigeration and Air Conditioning Engineers, MN SF = Minnesota Single Family Housing Standard, EPA = U.S. EPA Energy Star Plus Indoor Air Package Specifications (2007). Redrawn from NCHH summary chart Table 1: Summary of building testing findings TESTING SUMMARY NARRATIVE CALIBRATED BLOWER DOOR Findings The building shell was fairly tight based on current multifamily construction practices. The building was measured as having 0.38 cubic feet per minute of air leakage per square foot of conditioned space at 50 pascals (cfm/ft This can be compared with current air tight building practices for single family detached housing that can be measured at 0.24 cfm/ft Units 2 and 7 were substantially leakier than the building shell. Unit 2 was measured at 1.33 cfm/ft and unit 7 was 1.44 cfm/ft The leakage from unit to unit is higher than one would expect from a total renovation, with the leakage from unit to unit 3.5 to 3.8 times greater than the leakage from the unit to outdoors. With the interior walls not sealed at renovation, we have succeeded in reducing leakage from outdoors, but not leakage from one unit to another. This could be an issue with odors or smoke traveling from unit to unit. Comment/Considerations/Recommendation The renovation did not include the reconstruction of the interior partitions, nor did it allow for the sealing of existing leaks. There was considerable effort to improve the construction of the exterior shell adding insulation and new drywall. It is speculated but unconfirmed that mechanical, electrical and plumbing chases between units may be a source of unit to unit leakage. Future renovation should specify the sealing of all throughwall penetrations even when those penetrations do not require sealing to prevent fire spread. 3

4 FAN FLOW- KITCHEN FANS Findings The kitchen fan flows were measured in all units at high speed operation. The fans averaged only 84 cfm of flow. They were rated at 160 cfm and were performing at just over 52% of their rating. 75% of the rated flow or 120 cfm would be considered an acceptable performance level in accordance with the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) Standard 62.2 which requires 100 cfm for exhaust from the kitchen. Although a couple of the outside dampers appeared to be damaged and not able to open fully, most of the dampers were not obstructed. The low flow rate is more likely attributable to a ducting problem (see comments below) rather than an obstructed damper in most of the units. Comment/Considerations/Recommendation The kitchen fans low flow rates are attributed to the small duct size, equipment selection, and number of turns in ducts, all of which increase static pressure, thus causing reduced air flow. The renovation did not include the re-ducting of the kitchen fans due to the intention to minimize disturbance of the interior walls and ceiling during rehabilitation. Equipment options are limited given the budget, and fan power for these units is also limited. Jammed dampers were replaced after the building testing, but the system was not re-tested after the replacement. Future rehab projects should conduct duct flow tests of existing duct work in order to make better informed decisions regarding equipment size (fan horsepower) or possible inclusion of duct replacement and re-routing as part of the renovation. FAN FLOW- BATHROOM FANS Findings The bath fan flows were measured in all units. The fans averaged 66 cfm, above the level required by ASHRAE. The fans were rated at 80 cfm and were operating at approximately 82% of their rating. Comment/Considerations/Recommendation ASHRAE 62.2 requires 50 cfm from bathrooms for intermittent exhaust. The bathroom fans slightly exceed this performance on average. The duct runs for the bathrooms are generally short and straight, therefore duct static pressure losses are kept to a minimum. Nonetheless, future rehab projects should conduct duct flow tests of existing duct work prior to rehab in order to make better informed decisions regarding equipment size or possible inclusion of duct replacement as part of the renovation. PRESSURES INTERSTITIAL PRESSURES Findings The air handlers for heating and cooling have a central return grill located in the primary living space or hallway with individual supplies to the living room and bedrooms. In most cases, the air handler is located in a bedroom closet. A major concern for central returns is that without adequate area for return air streams they will generate positive pressure when the air handler is operating and bedroom doors are closed. The intention at Viking Terrace was to undercut the bedroom doors to provide a return air flow 4

5 pathway, however this solution proved to be inadequate. The individual bedrooms were found to have very high positive pressures when the air handler was in operation. For all bedrooms, including the ones with the air handler in the closets, the pressures were higher than what should be acceptable for winter operating conditions. For all bedrooms, the positive pressures averaged 6.07 pascals and for bedrooms without the air handler they averaged 7.25 pascals. This high positive pressure is not equalized by the intended air flow return path (under the bedroom doors). Therefore in addition to this return path, air and moisture could be driven into exterior walls or ceiling assembly. This could impact durability or cause odor transfer into the adjacent unit as the air follows the path of least resistance. Durability concerns include deterioration of structural components over time due to repeated wetting caused by condensate within the cavity when warm moist air comes in contact with cooler building assemblies. This could also result in failure of insulation and propagation of mold. Comment/Considerations/Recommendation In seeking a solution for this issue, pressure reduction tests were performed on two of the units with higher positive pressures. Units 2 and 9 had an exterior window opened to reduce the positive pressure to 3 pascals and the air flow exiting through the window openings calculated. Unit 2 required 139 cfm of air flow to reduce the pressures to 3 and unit 8 required 148 cfm for the same reduction. Based on these flows, 75 in 2 of return venting is needed from these rooms based on the requirement of 50 in 2 free return or transfer grille per 100 cfm. This would make additional undercutting of the doors impractical. In consultation with the architect, engineer, and developer it was decided that a transfer grill would be installed to link the bedrooms to the hallway and main living space, creating a return path and elevating the pressure. (See the section below on POST BUILDING EVALUATION MODIFICATIONS AND TESTING for complete results of follow testing and resolution of high pressures.) It is recommended that future projects incorporate transfer grills into the system designs. PRESSURES INTERSTITIAL PRESSURES: UNIT TO HALLWAY Findings With only the air handler operating, the units averaged 0.7 pascals negative to the common hallway. With both the air handler on and the bathroom fan running they averaged 1.16 pascals negative to the hallway; and with air handler, bathroom fan and kitchen fan they averaged 3.12 pascals negative to the hallway. Under any exhaust fan operation, these units will draw air from the central hallway into their units. Comment/Considerations/Recommendation Optimal unit to hallway pressure would be neutral or slightly negative to the hall to ensure that unit to unit transport of odors via the hall was limited. The levels recorded are within an acceptable range. DUCTS HEATING AND AIR CONDITIONING DUCT TIGHTNESS Findings Duct tightness was measured using a calibrated duct blaster and were measured at two different pressures. All air handling units tested were measured first at 25 pascals of pressure (the industry standard) and select units were measured at 50 pascals. The 50 5

6 pascal measurement was used because several of the air handlers were found to be operating at this higher pressure. For the ducts measured at 25 pascals of pressure the duct leakage (as a percent of total flow) was 71%. This is far leakier than one would specify for new systems. For those that were measured at 50 pascals of pressure, the average leakage was 105%. Comment/Considerations/Recommendation There was no mastic or sealant on any of the exposed duct in any of the units in this building, and most had gaps at the filter rack of ½ along the entire length of the filter cover. On the return visit on April 14 th 2008, we had the opportunity to inspect several of the air handlers in building 1, and noted that the ducts appeared to have been sealed with a caulk or mastic. No sealing efforts were noted in any of the duct systems in building The lack of duct sealing was also noted by the mechanical engineer and was on the punch list for the contractor. Inspection of visible ducts in the Spring of 2009 confirmed additional sealing was completed. Sealing of the ducts likely reduced the overall leakage rate for the systems. DUCTS HEATING AND AIR CONDITIONING DUCT FLOW Findings The measured average return flow for all the air handlers was 345 cfm, with the high measurement being 460 cfm and the low measurement being 215 cfm. The flows appear to be within +/- 10% of the rated flow from the manufacturer s table data sheets. Comment/Considerations/Recommendation The levels recorded are within an acceptable range. VENTILATION Findings Fresh air ventilation measurements for the 24 rehabilitated units in Building 1450 are provided in Appendix A. These measurements were compared with two standards: o The new ASHRAE 62.2 (2007) standard requires 30 cfm for the two-bedroom units and 39 cfm for the three-bedroom units (Ventilation rate is calculated as follows (number of bedrooms+1)*(7.5cfm)+(square feet*0.01cfm)). Green Communities Criterion 7-6 Ventilation requirement align with ASHRAE 62.2 and the mechanical ventilation requirements of EPA Energy Star with Indoor Air Package Specifications. o The Minnesota single family rate was also calculated as a comparison, it has a higher threshold. Under the Minnesota requirements, two-bedroom units would require 53 cfm and the three-bedroom units would require 69 cfm, although the Minnesota single family rate does not apply to Viking Terrace, which is a multifamily development. The system at Viking Terrace is designed to draw fresh air from the outside into the individual air handlers in the units. Under normal operating conditions, the air handlers run intermittently in response to the need for heating and cooling; however, the system was tested with the air handler running continuously during the test. Only three of the 24 6

7 units tested met or exceeded the ASHRAE requirement with the air handler running continuously. The average measured flow of fresh air with the air handler operating continuously was 70% of the required ventilation for the ASHRAE standard or approximately 21 cfm and 27 cfm, respectively, for two- and three-bedroom units. Bathroom and kitchen fans are unlikely to supplement this ventilation rate, as the ratio of leaks from unit to unit is much higher than the ratio of leaks from unit to outdoors. Owing to this fact, fresh air is three times more likely to be drawn from the adjacent units than from the outside. Only with the air handler in operation is it assured that ventilation air is drawn directly from the outside. During times when there is no heating or cooling, there may be less ventilation, unless windows are opened. Even during times when air is conditioned, the air handling unit does not operate continuously. As designed, the ventilation system could result in a serious energy penalty, although preliminary data show that energy efficiency for the building has improved dramatically. The wattage on the air handlers would consume an average of 6.5 Watts per cfm of ventilation air this is very high. The Health House program has a requirement for ventilation of no more than 0.5 watt per cfm or 1 watt per cfm if heat or energy recovery is used. Comments/Recommendation/Consideration Design of efficient systems for rehab projects of multi-family apartment buildings presents significant challenges, including limited equipment choices and sizing options, existing conditions which limit options, and budgetary constraints. While projects cannot control outside forces such as a lack of equipment choices, a number of strategies could be employed in future projects. Building on the existing design intention, these options include a secondary energy-efficient fan in the fresh air duct to improve air flow volume; and a thermostat with intermittent timer cycling to ensure that fresh air is brought in without regard for heat and cooling needs. Both strategies may result in an energy penalty related to heating and cooling. This consideration should be balanced against the need for fresh air ventilation. Proper sizing of flow rate and equipment would minimize the energy penalty. It is worth noting that the new system, even with its flaws, is a large improvement over the pre-rehab system, which consisted of no planned fresh air supply and unplanned fresh air infiltration through drafty, leaking building exteriors. The prerenovation system was both energy-inefficient and unhealthy. POST BUILDING EVALUATION MODIFICATIONS AND TESTING The findings of the building performance evaluation and testing led to retrofits at Viking Terrace which, it is believed, were generally successful in addressing the problems identified during the testing, with the possible exception of duct sealing. As noted above, testing revealed large pressure differences between the bedrooms (positive) and main living space (negative) of the units. Installation of transfer grills to equalize the pressure between the bedrooms and the main living space was suggested as a means of balancing the pressure in these enclosed spaces and was carried out in all three buildings by the contractor and paid for by Southwest Minnesota Housing Partnership (SWMHP). 7

8 Follow-up pressure testing was carried out in May Due to IRB requirements in place as part of the health study, post retro-fit pressures were taken only in units participating in the health study. The results of the testing and a comparison to the initial testing, when available, are shown in Table 2. Pre retro-fit data are only available from building The pre retro-fit pressure averaged 6.03 pascals and was reduced to 0.88 pascals. The overall average of units measured in all three buildings was 1.14 pascals. The data show that the transfer grills were effective in achieving large reductions in the high positive pressure in the bedrooms, which will help to minimize moisture incursion from the interior to the exterior wall assemblies. It was noted during the follow up testing that several residents had blocked in part or in whole the transfer grill. In unit a towel was placed over the grill and reduced its effectiveness, increasing pressure in the bedroom from 0.2 pascal unobstructed to 2.3 pascals with the obstruction in place. Unit was the highest found, and did not have any obstruction on the transfer grills. Other bedrooms with higher pressure differentials, bedroom 2 and bedroom 2, had ducted transfer grills due to structural constraints that did not permit the through wall option. Viking Terrace Interstitial Pressure (Pa) in Bedrooms Units Pre-retrofit Post-retrofit building unit location 3/26/2008 5/9/ bedroom one bedroom two bedroom one bedroom two (obstructed); 0.2 (unobstructed) bedroom one bedroom one bedroom two bedroom one bedroom two bedroom one bedroom two bedroom three bedroom one bedroom two bedroom one bedroom two bedroom three bedroom one bedroom two average bedroom one bedroom one bedroom two 5 average all units 1.14 Interstitial pressures measrued in pascals (Pa) with-in units between bedrooms and the main living space pre and post retro-fit with transfer grills. Pre-retrofit data is from March 07; Post-retrofit data is from May 08. Table 2: Viking Terrace Interstitial pressures test results. 8

9 Resident training is necessary and recommended to explain the importance of air flow between the bedroom and the main living space. Future projects with central air return options should include jump ducting or transfer grills to avoid this problem. Advance planning would allow for light and acoustic dampening grills to be specified, which would decrease resident desire to block or obstruct the grills. This was not possible at Viking Terrace due to structural and mechanical system obstructions. Additional duct sealing was also recommended and carried out on all air handlers and accessible ducts. Testing after the ducts were sealed was not conducted. BUILDING MONITORING Monitoring of the units participating in the health study was conducted for a period of approximately one year. This monitoring included tracking temperature and humidity in participating units in each building. A subset of units was also monitored for carbon dioxide (CO 2 ) levels. Total volatile organic compound (TVOC) testing was conducted seasonally, and radon testing was conducted annually. Temperature, Humidity and CO 2 Tracking Using ONSET HOBO dataloggers, temperature and relative humidity levels were tracked for the period of a year in 12 of the units participating in the health outcome study, representing 20% of the units at Viking Terrace. CO 2 levels were measured in 5 units. Data were retrieved quarterly from the dataloggers and compared with onsite outdoor conditions from data gathered by outdoor dataloggers. This information was used to determine if adequate ventilation is occurring within the units. Typically, two dataloggers were installed in each unit, one in the main living space near the thermostat, and a second in one bedroom. In a subset of units, additional loggers were installed to further examine temperature and relative humidity variation. Units Monitored thermostat, bedroom thermostat, bedroom, CO 2 in main living space thermostat, bedroom thermostat, 2 in bedroom (inside and outside wall), CO 2 in bedroom thermostat, bedroom thermostat, living room, bedroom thermostat, bedroom, CO 2 in living room thermostat, bedroom thermostat, bedroom thermostat, 2 in bedroom (inside and outside wall) CO 2 in living room thermostat, bedroom, CO 2 in living room thermostat, bedroom Due to resident tampering, data for unit was eliminated completely. Due to drain tile failure and subsequent water damage to unit , its data were eliminated and 9

10 residents relocated. Some data from Fall 2007 from unit were included in the overall building analysis. Temperature and Relative Humidity Analysis Approach Temperature and relative humidity data can provide insight into the overall performance of the building systems and ability to respond to external weather conditions. The data were examined to gain insight into several fundamental questions regarding building behavior: o Does the ventilation system or infiltration (air leakage from the exterior) account for the air exchange of the buildings? o Is the ventilation adequate to maintain reasonable humidity levels seasonally? o Do improvements to the exterior shell of the building and changes to the mechanical system result in higher surface temperatures and good humidity control? Ventilation system, infiltration and seasonal transitions Prior to the renovation of Viking Terrace, the apartments had no fresh air ventilation and relied on an exhaust only strategy via bathroom fans and kitchen range hoods. In addition, the building was under-insulated and drafty to due to air leakage through old windows. The renovation added insulation and air sealing to the exterior shell of the building and replaced the windows. Bathroom and kitchen exhaust was maintained and fresh air intake was added via the new mechanical system (see above for discussion of the efficacy of the system against state and national standards). Testing of the ventilation system in units of Building 1450 showed it provided an average of cfm of fresh air, or 70% of the ASHRAE standard when the system was running continuously. An examination of the relative humidity and dew points during seasonal change can suggest if ventilation or infiltration is responsible for air exchange in the building. If all units humidity levels decrease simultaneously and in a similar manner, then ventilation is dominant; if humidity levels in lower floor units decrease more than units on upper floors, then infiltration induced by the stack effect is likely to be playing a dominant role in building air exchange. Winter Transition Figure 1 shows a typical decline of indoor relative humidity in a unit over the course of a 12 week period from the middle of October through the first week in January. 10

11 Figure 1: Viking Terrace 10/07 12/08 (dotted line is temp, blue is relative humidity, and dash is dew point) The majority of units reached winter equilibrium of between 25% and 40% relative humidity during this period. To minimize the impact of variation in resident temperature preference, a comparison of dew point was utilized to examine humidity trends. Since the buildings are functionally separate, they behave differently from each other. Building 1440 is a two-story, 12-unit building with a slab-on-grade foundation. It is the smallest of the buildings and was renovated first. The comparison of data from stacked units (Figure 2) showed the lower level unit (1440-5) had a steeper decline in dewpoint from the beginning of the transition period when compared to the upper floor unit. This pattern indicates that stack effect rather than mechanical ventilation was the dominant cause of air exchange. Stack effect is a dominating force in most multi-story construction and difficult to eliminate entirely Dew point stacked units degree F int ext int ext week (16.Oct-7.Jan) Figure 2: Dew point comparison of stacked units in building 1440 during season transition fall to winter, measured in bedrooms on interior and exterior walls 11

12 1440 Dew point Interior Wall degree F week (16.Oct-7.Jan) Figure 3: Dew point comparison of scattered units in building 1440 during season transition fall to winter measured on interior walls This general pattern held for units located throughout the building, although it is less immediately apparent (Figure 3). Unit , which is located on the opposite side of the building from units , 10 and 11, is the exception to the overall trend. Unit has a single outside wall and shows a much more gradual decline in dewpoint levels, further suggesting that swing season ventilation is dominated by infiltration. Building 1450 is a three-story, 24-unit building with garden level apartments (the first floor is a half story below grade). It is the largest of the buildings and was renovated last. The data (Figure 4) revealed no clear pattern by floor. The random nature of the decrease suggests that infiltration although reduced by the renovation still contributes to the ventilation. If mechanical ventilation was the dominant source of fresh air, data from all units would be synchronous Dew point interior walls degree F week (16.Oct-7.Jan)

13 Figure 4: Dew point comparison of scattered units in building 1450 measured at interior walls Summer Transition The majority of units reached summer equilibrium of approximately 60% relative humidity in early to mid June. To minimize the impact of variation in resident temperature preference, a comparison of dew point is utilized to examine humidity trends. In building 1440, the transition to summer is an inverse to the pattern seen during October and November. Figure 5 shows an increase in humidity levels consist with an infiltration-dominated seasonal shift. As noted above, if mechanical ventilation was the dominant source of fresh air, data from all units would by synchronous Dew point interior walls degree F weeks (6.May-1.Aug) Figure 5: Dew point comparison of scattered units in building 1440 for Spring measured at interior walls In Building 1450, the transition to summer is an inverse to the pattern seen during October and November. Figure 6 shows a pattern of increase in humidity levels consistent with an infiltration-dominated seasonal shift. 13

14 1450 Dewpoint interior walls degree F weeks (6.May-1.Aug) Figure 6: Dew point comparison of scattered units in building 1450 during spring and summer measured at interior walls Results for building 1460 are inconclusive for both seasons due to the small number of units tracked in the building and the use by one resident of both humidifier and dehumidifier in the unit. Ventilation and season humidity Ventilation and humidity control vary seasonally. The need for indoor humidity control in summer is primarily driven by residential comfort needs; a secondary consideration is mold and fungal growth which can occur at humidity levels above 70%. Humidity control during the heating season is a balance of human comfort, health and building durability. Recommendations of appropriate winter indoor relative humidity levels vary but generally fall between 25% to 40%. Levels below 20% can cause drying of respiratory membranes and may compromise the bodies defense against infection. Summer The typical summer weather pattern for southwestern Minnesota demonstrated from outdoor data logged on site (Figure 7) creates a distinctive counter sine wave pattern when temperature and relative humidity are plotted. The highest relative humidity occurs during the lowest temperature of the day in the morning, and vice versa. 14

15 Figure 7: Outdoor temperature and relative humidity for the week of July (black line is temperature F left y-axis, blue is relative humidity left y-axis) Air conditioning in continual use, switched on and left on for extended periods running intermittently as temperature demands, will provide dehumidification and allow building assemblies to dry. Temperature and relative humidity data from unit (Figure 8) show a consistent use of air conditioning through June and July. Seasonal humidity levels stabilize around 55% RH. figure 8: Air conditioned unit May - July (black line is temperature F left y-axis, blue is relative humidity left y-axis) In contrast to the consistent use of air conditioning above, data from unit (figure 9) demonstrate intermittent use of the air conditioning system. This pattern is recognized by variable temperature day to day and relative humidity levels. 15

16 figure 9: intermittent use of air conditioning in unit May July (black line is temperature F left y-axis, blue is relative humidity left y-axis) These contrasting examples suggest that the air conditioning can maintain a relative humidity level appropriate for human comfort if used consistently. This level is below the mold growth level of 70% relative humidity. However, it is still above 50% relative humidity level necessary to decrease dust mite growth, which is more reliably controlled by regular house cleaning and laundering of bedding. Winter As noted above, temperature and humidity control during the heating season has impacts on human health and building durability. The key factors are air and surface temperatures and humidity. During extreme cold weather, the temperature of exterior walls and the air immediately adjacent to them is typically cooler than the overall ambient air temperature of the room. These cooler temperatures result in slightly higher relative humidity level readings at the wall. The difference between these temperatures is a function of insulation and air movement; it can therefore be mitigated by improved insulation and air sealing. At Viking Terrace, insulation was added to the exterior walls and roof of the building. Analysis of data from units with data loggers on outside and inside walls within the same room illustrates how the buildings react to extreme cold. The following examples, unit a second floor unit, and unit a first floor unit, compare inside and outside wall readings for the coldest week of the year with an average outdoor temperature of 1.67 degrees F and overnight lows of degrees F. Table 3 summarizes the maximum, minimum and average temperature, relative humidity and dew point for both the outside wall and interior wall conditions during the period examined in units and Figures 10 thru 14 below graph the data for the period. A temperature variation of approximately 2 to 3 degrees F between the interior and outside walls is consistent through out the period. Relative humidity levels also follow a pattern consistent with this temperature difference, and are slightly higher at the cooler outside wall. Habitation pattern and temperature preference account for the difference in temperature between the units. The higher relative humidity levels in unit are due to a humidifier in the unit. The dew point remains low throughout, and is 16

17 maintained at a level well below the outside wall temperature. Condensation is not a concern on the wall surface at these conditions. The windows in the unit are low-e argon filled glazing units, and should not have condensation under these conditions. Further, more surface temperatures are sufficiently warm to ensure thermal comfort of occupants. Viking Terrace Extreme Cold data Units and location outdoor office bd.in Temperature max min ave Relative Humidity max min ave Dewpoint max min ave Outdoor weather data recorded on site. Column naming abreviations are: bd - short bedroom; in - measurement on an inside wall; and out - measurement on an outside wall. Table 3: Extreme cold temperature and relative humidity data and bd.out bd.in bd.out Figure 10: outdoor weather at Viking Terrace 1/18/08 1/23/08 (dotted black line is temperature F left y-axis, blue is relative humidity left y-axis) 17

18 Figure 11: , inside wall data 1/18/08 1/23/08 (dotted line temperature F left y-axis, blue is relative humidity, and dash is dew point) Figure 12: , outside wall data 1/18/08 1/23/08 (dotted line temperature F left y-axis, blue is relative humidity, and dash is dew point) Figure 13: ,, outside wall data 1/18/08 1/23/08 (dotted line temperature F left y-axis, blue is relative humidity, and dash is dew point) 18

19 Figure 14: , outside wall data 1/18/08 1/23/08 (dotted line temperature F left y-axis, blue is relative humidity, and dash is dew point) The data indicate that insulation installed during the renovation is adequate to maintain surface temperature, and air movement is sufficient to avoid major moisture issues that may cause surface condensation. Due to the added insulation, the dew point for the indoor conditions is located inside the wall assembly. Vapor barriers installed as part of the rehab of the buildings should, if properly installed, prevent the warm moist interior air from reaching these cold surfaces and condensing inside the wall assembly. To date, there has been no evidence that condensation or mold growth is occurring. outdoor office bd.in bd.out Temperature max min ave Relative Humidity max min ave Dewpoint max min ave Carbon Dioxide (CO 2 ) 19

20 CO 2 levels were measured in a subset of six units. Due to tampering and equipment failure, data are available from only four units. Monitored data vary widely, and it is difficult to distinguish living patterns from ventilation effectiveness with confidence. CO 2 is naturally occurring in the atmosphere and is a by-product of combustion and human metabolism. The average outdoor level ranges from 300 ppm to 400 ppm. The guideline set forth by ASHRAE for schools, offices, and areas where people spend extended periods of time indoors is 1,000 ppm. The long-term average of CO 2 levels at Viking Terrace was 982 ppm, which is below the ASHRAE limit of 1,000 ppm. This is also well below the OSHA occupational exposure threshold of 5,000 ppm (table 4). The maximum reading for the year was 2,499 ppm. Viking Terrace Seasonal Carbon Dioxide Levels (ppm) 7/13-10/15/07 10/15/07-1/28/08 1/28-5/9/08 5/9-8/4/08 max min average max min average Table 4: Carbon dioxide levels at Viking Terrace 7/13/07-8/4/08 max min average max min average The data suggest that a combination of infiltration and ventilation is driving air exchange in the units. The design of the ventilation system brings fresh air into the unit only when heating or cooling is called for by comfort demand. There are periods of time when no or little fresh air is entering the unit by mechanical means. If mechanical ventilation was the primary driver of air exchange, the data should show a strong correlation between temperature trend and CO 2, although this could be confounded by use of windows or other non-mechanical methods of ventilation. Figure 15 shows a correlation between temperature control (air condition on) and CO 2 levels. Figure 15: , carbon dioxide levels 7/1/08 7/7/08 (dotted line temperature F left y-axis, blue is relative humidity, and green is ppm CO 2 ) 20

21 Figure 16 appears to show the impact of open windows as levels drop rapidly and approach average outdoor ambient levels. Figure 16: , carbon dioxide levels 7/1/08 7/7/08 (dotted line temperature F left y-axis, blue is relative humidity, and green is ppm CO 2 ) 21

22 Total Volatile Organic Compounds A measure of total volatile organic compounds (TVOC) was conducted in participating units and building common areas on a seasonal basis (November 2007, January 2008, May 2008 and July 2008). This testing was conducted using 3M 3500 Organic Vapor Monitors (a passive diffusion monitor) with an exposure time of three days or approximately 72 hours. The monitors were processed by Braun Intertec, a local lab in Minneapolis, Minnesota. TVOC are being reported as Total Hydrocarbons as TOLUENE. The EPA has no standards set for Total VOCs in non-industrial settings and no toxicological basis has been established for setting such a standard. (US EPA, An Introduction to Indoor Air Quality, Organic Gases (Volatile Organic Compounds VOCs). Accessed, last updated on Monday, 26.January 2009 ( The results indicate that all individual VOC exposures were below the ATSDR Minimum Risk Levels. Total VOCs as Toluene ranged from 344 μg/m3 to 2687 μg/m3. Viking Terrace TVOC as Toluene Levels (μg/m 3 ) building unit November st floor hall nd floor hall st floor hall nd floor hall n/a st floor hall (6) st floor hall (7) rd floor hall Data converted from ppm to μg/m 3 as follows: μg/m 3 = (((ppm)*(gram molecular weight of substance)) / 24.45)*1000. Where = molar volume of air in liters at normal temperature and pressure, and Toluene's gram molecular weight is grams. table 5: Total Volatile Organic Compounds levels - THC as Toluene μg/m 3 January The Committee on Sick House Syndrome outlined the following guidance with regard to their recommendation, This value is gained, as low as reasonably achievable, from the May July 22

23 actual investigation of residential indoor VOC concentration in our country and an assumption. The TVOC advisable value is expected to be use for indicating the extent of indoor air quality. As it is not based on toxicological data, it must be treated separately from each individual VOC guideline value. Research and studies are further promoted to validate the advisable value and to set up the TVOC guideline based on health assessment. (Committee on Sick House Syndrome: Indoor Air Pollution. Progress Report No.2 15.December 2000.) According to the US EPA the indoor air VOC content can be from 2 to 5 times outdoor levels and may rise to 1,000 times background levels due to activities such as paint stripping. Residential environments may have levels reaching 1000 µg/m 3, primarily because of frequent use of cleaners, consumer products, and on-going processes such as cooking (Aerias: Air Quality Sciences, VOCs: A Major Contributor to Indoor Pollution The test results from July 2008 may be higher due to carpet cleaning that occurred during the test period. The higher VOC levels in the hall ways maybe the result of air fresheners installed in them to mask cooking odors, and the lack of ventilation to flush the air from the common areas. The high levels in general may also be attributed in part by the decreased flows from the kitchen hoods (50% of rated flow), which significantly impairs the effectiveness of a major point source exhaust (cooking). It is important to recognize that the TVOC test is a catch all and does not differentiate the VOC type; some VOCs measured in the TVOC levels may be benign. In addition to TVOC testing, a subset of unit and common area samples were analyzed to characterize the nature of the volatile organic compounds found utilizing a standard solvent panel test (Braun Intertec). The standard solvent panel included the following compounds: 1,1,1-Trichloroethane 2-Ethoxyethyl Acetate Acetone Benzene Chlorobenzene Chloroform Ethanol Ethyl Acetate Ehtyl Benzene Isobutanol Isopropanol Methyl Ethyl Ketone Methyl Isobutyl Ketone Methylene chloride n-butyl Acetate n-hexane Stoddard Solvent Styrene Tetrachloroethene Tetrahydrofuran Toluene TPH as Gasoline Trichlorethene VM&P Napththa Xylenes, Total The analytical test results are in the tables below. Compounds in bold above and in tables 6-10 were detected in at least one unit during one test at Viking Terrace. The vast majority of organics measured were well below established federal occupational health standards and other standards. The exception to this pattern was a high benzene level measured in July 2008 in two units (see below for discussion). 23

24 Viking Terrace: Novemeber 2007 Solvent Panel a Volatile Organic Compounds (parts per million) compound building - unit number MRL b H H3 Total Hydrocarbons as TOLUENE ,1,1-Trichloroethane < < < < < < Ethoxyethyl Acetate < < < < Acetone < < <0.086 < < < Benzene < <0.006 < < < < Chlorobenzene < < < < < < Chloroform < < < < < < Ethanol c EthylAcetate < < < < < Ehtyl Benzene < < < < < < Isobutanol c < < < < < < Isopropanol c < < < <0.025 <0.025 <0.025 Methyl Ethyl Ketone < < < < < Methyl Isobutyl Ketone < < < < < < Methylene chloride < < < < < < n-butyl Acetate < < < < < < n-hexane < < < < < < Stoddard Solvent Styrene < < < < < < Tetrachloroethene < < < < < Tetrahydrofuran < < < < < Toluene < < < < < < TPH as Gasoline Trichlorethene < < < < < VM&P Napththa < < < < < Xyelenes, Total < < < < < < a Solvent Panel is a standard VOC screening test conducted by Braun Intertec. b MRL abbreviates Method Recovery Limit c The recovery study yielded results of <75%. Per the NIOSH Manual of Analytical Methods, the result is considered semi-quantitative. table 6: Solvent Panel November

25 Viking Terrace: January 2008 Solvent Panel a Volatile Organic Compounds (parts per million) compound building - unit number MRL b H H3 Total Hydrocarbons as ,1,1-Trichloroethane < < < < < < Ethoxyethyl Acetate < < < < < Acetone < < < < < < Benzene < < < < < < Chlorobenzene < < < < > < Chloroform < < < < < Ethanol c EthylAcetate < Ehtyl Benzene < < < < < < Isobutanol c < < < < < < Isopropanol c < < < < < Methyl Ethyl Ketone < < < < < < Methyl Isobutyl Ketone < < < < < Methylene chloride < < < < < < n-butyl Acetate < < < < < n-hexane < < < < < Stoddard Solvent < Styrene < < < < < < Tetrachloroethene < < Tetrahydrofuran < < < < < < Toluene < < < < < TPH as Gasoline Trichlorethene < < < < < < VM&P Napththa < < < < < Xyelenes, Total < < < < < < a Solvent Panel is a standard VOC screening test conducted by Braun Intertec. b MRL abbreviates Method Recovery Limit c The recovery study yielded results of <75%. Per the NIOSH Manual of Analytical Methods, the result is considered semi-quantitative. table 7: Solvent Panel January

26 Viking Terrace: May 2008 Solvent Panel a Volatile Organic Compounds (parts per million) compound building - unit number MRL b H H3 Total Hydrocarbons as TOLUENE ,1,1-Trichloroethane < < < < < < Ethoxyethyl Acetate < < < < < Acetone < < < < < Benzene < < < < < < Chlorobenzene < < < < < < Chloroform < < < < < Ethanol c EthylAcetate < < < < < < Ehtyl Benzene < < < < < < Isobutanol c < < < < < < Isopropanol c < < < < < < Methyl Ethyl Ketone < < < < < Methyl Isobutyl Ketone < < < < < < Methylene chloride < < < < < < n-butyl Acetate < < < < < < n-hexane < < < < < < Stoddard Solvent d Styrene < < < < < < Tetrachloroethene < < < Tetrahydrofuran < < < < < < Toluene < < < < < TPH as Gasoline Trichlorethene < < < < < < VM&P Napththa e < < < < < Xyelenes, Total < < < < < < a Solvent Panel is a standard VOC screening test conducted by Braun Intertec. b MRL abbreviates Method Recovery Limit c The recovery study yielded results of <75%. Per the NIOSH Manual of Analytical Methods, the result is considered semi-quantitative. d The Blank Spike Duplicate recovered high at 126%. The laboratory limits are %. This may indicate a high bias to the reported results. e The Relative Percent Difference was high at The laboratory limit is 20. This may indicate greater uncertainty to the accuracy of the reported results. table 8: Solvent Panel May

27 Viking Terrace: July 2008 Solvent Panel a Volatile Organic Compounds (parts per million) compound building - unit number 1460-H H1 7 MRL b H H Total Hydrocarbons as TOLUENE ,1,1- Trichloroethane < < < < < < Ethoxyethyl Acetate < < < < < < < Acetone < < < < < < Benzene < < < < < Chlorobenzene < < < < < < < Chloroform < < < < < < < Ethanol c EthylAcetate < < Ehtyl Benzene < < < < < < < Isobutanol c < < < < < < < Isopropanol c < < < < < < < Methyl Ethyl Ketone < < < < < < Methyl Isobutyl Ketone < < < < < < < Methylene chloride < < < < < < < n-butyl Acetate < < < < < < < n-hexane < < < < < < < Stoddard Solvent Styrene < < < < < < < Tetrachloroethene < < < < Tetrahydrofuran < < < < < < < Toluene < < < < < TPH as Gasoline Trichlorethene < < < < < < VM&P Napththa < < < < < < Xyelenes, Total < < < < < < a Solvent Panel is a standard VOC screening test conducted by Braun Intertec. b MRL abbreviates Method Recovery Limit c The recovery study yielded results of <75%. Per the NIOSH Manual of Analytical Methods, the result is considered semi-quantitative. d The Blank Spike Duplicate recovered high at 126% and the Blank Spike Duplicate recovered high at 127%. The laboratory limits are %. This may indicate a high bias to the reported results. table 9: Solvent Panel July

28 Viking Terrace: April 2009 Solvent Panel a Volatile Organic Compounds (parts per million) compound building - unit number MRL b Total Hydrocarbons as TOLUENE ,1,1-Trichloroethane < < Ethoxyethyl Acetate < < Acetone < < Benzene < Chlorobenzene < < Chloroform < < Ethanol c EthylAcetate < < Ehtyl Benzene < < Isobutanol c < < Isopropanol c Methyl Ethyl Ketone < < Methyl Isobutyl Ketone < < Methylene chloride < < n-butyl Acetate < < n-hexane < < Stoddard Solvent Styrene < < Tetrachloroethene < < Tetrahydrofuran < < Toluene < < TPH as Gasoline Trichlorethene < < VM&P Napththa < < Xyelenes, Total < < a Solvent Panel is a standard VOC screening test conducted by Braun Intertec. b MRL abbreviates Method Recovery Limit c The recovery study yielded results of <75%. Per the NIOSH Manual of Analytical Methods, the result is considered semi-quantitative. table 10: Solvent Panel April 2009 Exposure levels and potential health effects for all detectable compounds are summarized below. The primary source for this information was the Department of Health and Human Services Agency for Toxic Substances & Disease Registry (ATSDR). The majorities of exposure limits come from the industrial sector, and are set for an 8 hour period and maximum short term exposure. The ATSDR also sets limits for chronic exposure for some chemical groups. Unlike industrial exposure limits, these measures may more closely mimic long term low level exposure likely to be found in the residential environment. 28

29 Compound Summaries 1,1,1-Trichloroethane According to ATSDR, 1,1,1-trichloroethane is a synthetic chemical that does not occur naturally in the environment. No 1,1,1-trichloroethane is supposed to be manufactured for domestic use in the United States after January 1, 2002 because it affects the ozone layer. 1,1,1-Trichloroethane had many industrial and household uses, including use as a solvent to dissolve other substances, such as glues and paints; to remove oil or grease from manufactured metal parts; and as an ingredient of household products such as spot cleaners, glues, and aerosol sprays. The ATSDR lists the health risks of 1,1,1- tricholorethane as dizziness and loss of coordination. At higher levels exposure can cause a loss in blood pressure and cardiac arrest. The health impacts of low levels are not known. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to 1,1,1-trichlorethane at 0.7ppm. 2ppm is the minimum risk level for acute exposure. The maximum level measured at Viking Terrace was 0.007ppm. 2-Ethoxyethyl Acetate 2-Ethoxyethyl Acetate is a solvent found in some household and industrial products. ATSDR lists the possible health effects from exposure as: irritation of eyes, nose; vomiting; kidney damage; headache, dizziness, drowsiness, paralysis, unconsciousness; in animals: reproductive, teratogenic effects, nausea, vomiting. OSHA lists an 8-hour time-weighted average exposure limit of 100ppm. NIOSH places the immediate threat to human health exposure level at 500ppm. Several other countries, listed in the NIOSH registry of toxic effects of chemical substances, have extended exposure limits of 5 to 10ppm. The maximum level measured at Viking Terrace was 0.02ppm. Acetone Acetone is a colorless solvent with a distinctive smell. ATSDR lists the possible risks of exposure to acetone as irritation of eyes, nose, throat; sore throat, cough; headache, dizziness, drowsiness, confusion, CNS depression, unconsciousness; eye redness, pain, blurred vision, dermatitis, nausea, vomiting. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to acetone at 13 ppm. 26ppm is the minimum risk level for acute exposure. OSHA sets a limit of 1,000ppm for a normal 40-hour work week, other organizations such as NIOSH place the recommended level of exposure lower; for example, NIOSH has a recommended exposure level of 250ppm. The maximum level measured at Viking Terrace was ppm. Benzene According to the ATSDR, benzene is a colorless liquid with a sweet odor. It evaporates into the air very quickly and dissolves slightly in water. It is highly flammable and is formed from both natural processes and human activities. Benzene is widely used in the United States; it ranks in the top 20 chemicals for production volume. Exposure of the general population to benzene mainly occurs through breathing air that contains benzene. The major sources of benzene exposure are tobacco smoke, automobile service stations, exhaust from motor vehicles, and industrial emissions. Vapors (or gases) from products that contain benzene, such as glues, paints, furniture wax, and detergents, can also be a source of exposure. Auto exhaust and industrial emissions account for about 20% of the 29

30 total national exposure to benzene. About half of the exposure to benzene in the United States results from smoking tobacco or from exposure to tobacco smoke. The average smoker (32 cigarettes per day) takes in about 1.8 milligrams (mg) of benzene per day. This amount is about 10 times the average daily intake of benzene by nonsmokers. ATSDR lists the possible health risks of inhaled benzene as drowsiness, dizziness, rapid heart rate, headaches, tremors, confusion, and unconsciousness and death. Prolonged exposure has also been linked to immune system weakening and other detrimental health impacts. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to benzene at 0.003ppm ppm is the minimum risk level for acute exposure. The maximum level measured at Viking Terrace was ppm. During the July 2008 round of TVOC sampling, a high level of benzene was detected in two units in two different buildings. Detectable levels of benzene were not found at any other time during the study period. Benzene is a component of tobacco smoke and the high level present in one unit may be due to resident smoking. Retesting of the effective units in April of 2009 showed the Benzene levels had decreased. Residents reported a discontinuation of smoking in the unit. Chloroform According to the ATSDR, chloroform is a colorless liquid with a pleasant, nonirritating odor and a slightly sweet taste. Today, chloroform is used to make other chemicals and can also be formed in small amounts when chlorine is added to water. The ATSDR website lists the possible health impacts of breathing chloroform: Breathing about 900 ppm for a short time can cause dizziness, fatigue, and headache. Breathing air, eating food, or drinking water containing high levels of chloroform for long periods of time may damage your liver and kidneys. Large amounts of chloroform can cause sores when chloroform touches your skin. It isn't known whether chloroform causes reproductive effects or birth defects in people. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to chloroform at 0.02ppm. 0.1ppm is the minimum risk level for acute exposure. The maximum level measured at Viking Terrace was ppm. Ethanol Ethanol is a naturally occurring and manmade hydrocarbon. There is little information available on the specific health risks of ethanol, though specific forms and isomers of ethanol have higher health hazards. OSHA lists the exposure maximum to ethanol at 1000ppm. The maximum level measured at Viking Terrace was 2.210ppm. Ethyl Acetate Ethyl acetate is a colorless solvent with a characteristic odor. NIOSH lists the possible health impacts of ethyl acetate as: cough, dizziness, drowsiness, headache, nausea, sore throat, unconsciousness, weakness. OSHA lists the exposure maximum to ethyl acetate at 300ppm. The maximum level measured at Viking Terrace was 0.029ppm. Isopropanol Isopropanol, also known as rubbing alcohol is a highly flammable, colorless liquid with a strong odor. The possible health risks to airborne exposure to isopropanol according to 30

31 OSHA are eye, nose, throat irritation; headache, drowsiness, dizziness, headache; dry cracking skin. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to isopropanol at 400ppm. The maximum level measured at Viking Terrace was ppm. Methyl Ethyl Ketone From the ATSDR website: Methyl ethyl ketone (MEK) is a manufactured chemical but it is also present in the environment from natural sources. It is a colorless liquid with a sharp, sweet odor. MEK is produced in large quantities. Nearly half of its use is in paints and other coatings because it will quickly evaporate into the air and it dissolves many substances. It is also used in glues and as a cleaning agent. Possible health impacts of MEK according to the ATSDR are irritation of the nose, throat, skin, and eyes. If MEK is breathed along with other chemicals that damage health, it can increase the amount of damage that occurs. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to MEK at 200ppm for a normal 8-hour workday. The maximum level measured at Viking Terrace was ppm. n-butyl Acetate N-butyl acetate is a colorless liquid with a characteristic odor. NIOSH lists the possible health impacts of n-butyl acetate exposure as irritation of eyes, skin, upper respiratory system; headache, drowsiness, narcosis. OSHA lists the exposure maximum to n-butyl Acetate at 150ppm. The maximum level measured at Viking Terrace was ppm. Stoddard Solvent From the ATSDR website: Stoddard solvent is a colorless, flammable liquid that smells and tastes like kerosene. Stoddard solvent is a petroleum mixture that is also known as dry cleaning safety solvent, petroleum solvent, and varnoline. It is a chemical mixture that is similar to white spirits. Stoddard solvent is used as a paint thinner; in some types of photocopier toners, printing inks, and adhesives; as a dry cleaning solvent; and as a general cleaner and degreaser. According the ATSDR, stoddard solvent can affect your nervous system and cause dizziness, headaches, or a prolonged reaction time. It can also cause eye, skin, or throat irritation. In animals exposure has caused seizures and bronchitis. OSHA lists the exposure maximum to stoddard solvent at ppm, depending on the industry. The maximum level measured at Viking Terrace was ppm. Tetrachloroethene From the ATSDR: Tetrachloroethylene is a manufactured chemical that is widely used for dry cleaning of fabrics and for metal-degreasing. It is also used to make other chemicals and is used in some consumer products. Possible health hazards of tetrachloroethene according to the ATSDR: High concentrations of tetrachloroethylene (particularly in closed, poorly ventilated areas) can cause dizziness, headache, sleepiness, confusion, nausea, difficulty in speaking and walking, unconsciousness, and death. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to tetrachloroethene at 0.04ppm, and 0.2ppm is the minimum risk level for acute exposure. The maximum level measured at Viking Terrace was ppm. 31

32 Toluene Toluene is a petroleum byproduct that in sufficient quantities can adversely affect the human nervous system, with health effects ranging from headaches to loss of coordination and other nervous system function. In high enough concentrations exposure to toluene can be fatal. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to toluene at 0.08ppm. 1ppm is the minimum risk level for acute exposure. OSHA sets a limit of 100ppm for a normal 40-hour work week, though lower allowable limits have been sought. The ACGIH recommends a limit of 50ppm for an 8 hour shift. The maximum level measured at Viking Terrace was ppm. Total Petroleum Hydrocarbons (TPH) as Gasoline From the ATSDR website: TPH is a term used to describe a large family of several hundred chemical compounds that originally come from crude oil. Possible health impacts, according to ATSDR, of TPH include headaches and dizziness, nervous disorders, effects on the blood, immune system, lungs, skin and eyes. OSHA lists the exposure limits to TPH at 500ppm. The maximum level measured at Viking Terrace was ppm. Trichlorethene From the ATSDR website: Trichloroethene (TCE) is a nonflammable, colorless liquid with a somewhat sweet odor and a sweet, burning taste. It is used mainly as a solvent to remove grease from metal parts, but it is also an ingredient in adhesives, paint removers, typewriter correction fluids, and spot removers. According to the ATSDR, possible health impacts of TCE: Breathing small amounts may cause headaches, lung irritation, dizziness, poor coordination, and difficulty concentrating. Breathing large amounts of TCE may cause impaired heart function, unconsciousness, and death. Breathing it for long periods may cause nerve, kidney, and liver damage. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to TCE at 0.1ppm, and 2ppm is the minimum risk level for acute exposure. The maximum level measured at Viking Terrace was ppm. VM&P Naphtha VM&P Naphtha is a chemical solvent, and is also known as painter s naphtha, petroleum ether, petroleum spirit. It is used in several industrial and construction industries, including in some finishes. OSHA places an exposure limit of 300ppm on VM&P naphtha. The maximum level measured at Viking Terrace was 0.575ppm. Total Xylene From the ATSDR website: Xylene is a colorless, sweet-smelling liquid that catches on fire easily. It occurs naturally in petroleum and coal tar. Chemical industries produce xylene from petroleum. It is one of the top 30 chemicals produced in the United States in terms of volume. Xylene is used as a solvent and in the printing, rubber, and leather industries. It is also used as a cleaning agent, a thinner for paint, and in paints and varnishes. It is found in small amounts in airplane fuel and gasoline. According to the ATSDR, possible health impacts of xylene exposure: High levels of exposure for short or 32

33 long periods can cause headaches, lack of muscle coordination, dizziness, confusion, and changes in one s sense of balance. Exposure of people to high levels of xylene for short periods can also cause irritation of the skin, eyes, nose, and throat; difficulty in breathing; problems with the lungs; delayed reaction time; memory difficulties; stomach discomfort; and possibly changes in the liver and kidneys. It can cause unconsciousness and even death at very high levels. The ATSDR lists the minimum health risk level for inhaled, chronic exposure to xylene at 0.05ppm, and 2ppm is the minimum risk level for acute exposure. The maximum level measured at Viking Terrace was ppm. 33

34 RADON MONITORING Radon testing was conducted in two of three complex buildings (1440 and 1460). The results of the testing are summarized in table 11. Alpha track long term radon tests, 90 plus day tests were placed on 7 January 2007 and collected on 14 April Radon testing of the third and final building (1450) was not conducted due to ongoing construction; testing of this building was conducted during the winter of , along with a re-test of units in buildings tested in winter These long-term tests were conducted after the rehabilitation of the buildings was complete but before any radon mitigation occurred. The EPA does not have guidelines for testing in multi-family buildings. With guidance from state experts the test plan was established. These tests were placed in all ground connected units, and in common areas on all floors. Where a fire wall crossed the building tests were placed in common areas on both sides. The testing in 2007 show units in both buildings 1440 and 1460 reporting radon levels at or above the EPA action level of 4.0 pci/l. Unit 5 in 1440 tested 4.5 pci/l, and unit 3 in 1460 tested at 4.0 pci/l. Unfortunately, the majority of tests placed in 1440 were moved or removed by residents and therefore we do not have data on all ground connected units in the building. Test results indicated levels in several units above the EPA action level for mitigation of 4.0 pci/l. Southwest Minnesota Housing Partnership (SWMHP), the owner/developer of Viking Terrace, agreed to mitigate radon in all buildings. A mitigation system was installed on buildings 1450 and The system is exterior to the building. It utilizes the existing foundation drain tile and sub-slab plumbing in conjunction with exterior vertical stacks to create the necessary pressure field and vent soil gas to the atmosphere. Preliminary short-term monitoring of the system showed it effectively lowered radon levels to below 2 pci/l. Long term follow-up radon testing was conducted from February 2009 to May 2009 postradon mitigation (see table 12).. The testing was done using RSSI Alpha-track radon gas detector by the radon mitigation specialist hired by SWMHP. The data showed a measurement for one unit at 2.2 pci/l in both the mechanical room and the living space. Results for the rest of the units were mostly below 1.0 pci/l, with many readings at 0.7 plus or minus 0.3 pci/l. Data taken in both the mechanical room and a location within the living space showed close correlation in most units with all averaging below 1 pci/l. Only two units had radon readings close to background in the mechanical closet and twice that in the living space. 34

35 Viking Terrace Pre and Post Construction Radon Levels pre-construction post construction Test 1 Test 2 Average Test 3 Jan 06 a Mar 06 b Jan Apr 07 c building unit results pci/l results pci/l results pci/l results pci/l missing 1' missing missing missing missing 4' missing st floor hall nd floor hall no test no test no test no test no test 5' 2.7 no test no test no test no test 1st floor hall 2.6 no test ' 2.1 west hall east hall 1 2 west 2 1 east west east Blank 1 <0.4 Blank 2 <0.4 a The first testing was conducted from thru approx 66hrs b The second testing was conducted from thru approx 64hrs c Post construction (pre-radon mitigation) testing was conducted from thru Table 11: Summary of radon testing at Viking Terrace Apartments 35

36 Viking Terrace Post Mitigation Radon Levels a building unit location results pci/l mechanical room living space (lvr) mechanical room living space (bdr) living space (lvr) mechanical room mechanical room mechanical room living space (lvr) mechanical room mechanical room living space (bdr) mechanical room mechanical room (dup) mechanical room living space (lvr) mechanical room living space (lvr) mechanical room mechanical room living space (lvr) living space (bdr) mechanical room mechanical room mechanical room living space (bdr) 1.0 a Test exposures from 2/7/09 to 5/14/09 Table 12: Summary of post mitigation radon testing at Viking Terrace Apartments A mitigation system for building 1440 is expected to be completed in the late spring of 2009, with follow-up testing in Winter Differences in foundation structure of building 1440 require a slight modification to the system installed at 1450 and

37 Conclusion As a pilot project, the Viking Terrace Apartments study has proved to very valuable in further the understanding of building behavior, sustainable renovation and the green design process in the region. Although it did not meet all performance criteria, the renovation is a clear success. First and foremost, the project extends the useful life of 60 much needed units of affordable housing, and is now providing quality housing for families in Worthington. It has dramatically reduced energy and water use (see Appendix B: and improved thermal comfort of the residents with the addition of insulation, new windows and new mechanical systems which provide year round air tempering. As a first generation sustainable housing renovation, the project and its developer Southwest Minnesota Housing Partnership and funders took a large step forward. The findings of this report underscore the complexity of the task to design and build sustainable residential building renovation projects. The evaluation of the project made apparent that the use of building science and sustainable practices as tools for design are still in the early stages of wide adoption. Metrics and outcomes are as yet not well understood or in some cases are not yet defined. Several issues are of note. First, there are often apparent contradictions and goals in a housing development. What is considered to be a good or acceptable outcome by one party may not meet the needs of another party. For example, the indoor humidity level during the summer months at Viking Terrace meets some but not all expectations. From a building performance view point, 55% relative humidity, the average humidity level at Viking Terrace, is considered reasonable from an energy, comfort, mold prevention, and building performance standpoint. In addition, the energy reduction goal for the project was met. However, the relative humidity level necessary to retard the growth of dust mites, a common allergen, is 50% or less. Therefore, from a health perspective, this relative humidity level does not meet the preferred standard for addressing all issues related to health. This raises the questions: What is the appropriate level and expectation when balancing all needs including energy, health and comfort? What are reasonable performance perimeters for a building? What is the role of the occupant in maintaining a healthy environment? While we can offer clarification of these questions, we have no direct answer. We can say that understanding the goals and the relationships of what is needed to meet those goals will lead to better outcomes. Acknowledging and treating buildings, their behavior and the living patterns of occupants as the complex dynamic systems that they are, rather then as static boxes (with no people) as they are often perceived, will lead to better outcomes in the future. The production of housing based on a verity of performance goals underscores the need for early formation of an integrated design team. Current practice with caps on predevelopment soft costs establishes budget and scope in order to apply for financing before engaging a team. Early engagement would allow for an interdisciplinary team to bring their expertise to a goal setting session. Understanding the needs and concerns of all groups earlier in the process allow solutions to be designed into the project, a process that is more cost effective then redesign or adding a fix when an issue arises. 37

38 Ventilation is a significant challenge for renovation projects. Viking Terrace had no fresh air prior to renovation; however, as currently designed, the system brings in fresh air only when the fan unit is running to meet the demand for heating and cooling. This simple system is capable of providing 70% of the ASHRAE standard (measured and calculated during the building evaluation) if run constantly. While the relationship between energy and ventilation is well understood over ventilating will result in an energy penalty the design of systems that balance these issues is not a simple task. The goal for ventilation was not met. Questions arise regarding not only the design of the system but also regarding what is enough fresh air to maintain air quality? What should the goal be? how do we define and measure it? Meeting a standard is just the threshold. Related to the issue of ventilation is the measurement and understanding of volatile organic compound (VOC) levels in an indoor environment. The health impacts of some individual VOCs are understood. It is also clear that measuring TVOC (total volatile organic compounds) is not an indication of potential health risk associated with exposure. Further study and clarification of residential VOC sources, measurement, benchmarking of acceptable exposure level and their long term impact on human health is necessary. The radon detection and mitigation in renovation projects for multifamily buildings has advanced since this project was planned and built. The American Association of Radon Scientists and Technologists is working to develop protocols for multifamily testing and mitigation. The progress at Viking Terrace has been slow but successful. Minnesota has adopted mandatory radon construction techniques for single family new construction, and Minnesota Housing the state s housing finance agency requires radon resist construction for new multi-family in EPA Radon Zone 1. They are currently working on policy for the inclusion of testing and mitigation for multi-family renovation. There were valuable lessons learned regarding building testing. The results of the building evaluation post construction underscore the need for pre-renovation building testing and post-renovation commissioning. Pre-design building testing would have allowed for a proper scoping of the work need to ensure intended outcomes. An example of this is the kitchen hood ductwork. Testing prior to construction would have revealed that the existing duct work was inadequate and needed to be replaced or at least resealed. This would likely have resulted in better flow levels from the hoods, and a decrease in both pollutants and moisture associated with cooking. The building evaluation revealed several issues that would have been detected by postconstruction commissioning, including inadequate duct sealing and high interstitial air pressures stemming from a poor air return path to the air handler. Improvements to air sealing and the installation of jump ducts improved the performance of the air handling system and air circulation within the units. It is noteworthy that the developer, Southwest Minnesota Housing Partnership, now tests for radon in all projects and conducts building evaluation testing on renovation projects as part of pre-design work. 38

39 Sources ATSDR Minimal Risk Levels (MRL s). Agency for Toxic Substance and Disease Registry Website. Updated 2007, ATSDM, Accessed September 27, < Total Hydrocarbons as Toluene Public Health Statement - Toluene Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, < Trichlorethane Toxic Substance Fact Sheet - Trichloroethane Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, < 2-Ethoxyethyl Acetate Chemical Sampling Information - 2-Ethoxyethyl Acetate. Occupational and Health Hazard Agency Website. OSHA. Accessed September 27, < The Registry of Toxic Effects of Chemical Substances: Ethanol, 2 - ethoxy -, acetate. National Institute for Occupational Safety and Health Website. NIOSH. Accessed September 27, < Acetone Chemical Sampling Information - Acetone. Occupational and Health Hazard Agency Website. OSHA. Accessed September 27, < Benzene Toxic Substance Fact Sheet - Benzene Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, < Chloroform Toxic Substance Fact Sheet - Trichloroethane Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, < Ethanol OSHA Permissible Exposure Limit (PEL) for General Industry. Occupational and Health Hazard Agency Website. OSHA. Accessed September 27, < _id=9992&p_text_version=false> EthylAcetate 39

40 NIOSH Pocket Guide to Chemical Hazards Ethyl Acetate. Center for Disease Control Website. CDC. Accessed September 27, < NIOSH Pocket International Safety Chemical Card Ethyl Acetate. Center for Disease Control Website. CDC. Accessed September 27, < > Isopropanol NIOSH Pocket Guide to Chemical Hazards Isopropanol. Center for Disease Control Website. CDC. Accessed September 27, < Chemical Sampling Information - Isopropanol. Occupational and Health Hazard Agency Website. OSHA. Accessed September 27, < Methyl Ethyl Ketone Toxic Substance Fact Sheet 2-Butanone Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, < n-butyl Acetate NIOSH Pocket International Safety Chemical Card n-butyl acetate. Center for Disease Control Website. CDC. Accessed September 27, < Chemical Sampling Information - Isopropanol. Occupational and Health Hazard Agency Website. OSHA. Accessed September 27, < Stoddard Solvent Toxic Substance Fact Sheet Stoddard Solvent Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, < Chemical Sampling Information Stoddard Solvent. Occupational and Health Hazard Agency Website. OSHA. Accessed September 27, < Tetrachloroethene Toxic Substance Fact Sheet Tetrachloroethene Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, Toluene 40

41 See total hydrocarbons as toluene entry TPH as Gasoline Toxic Substance Fact Sheet TPH Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, < Trichlorethene Toxic Substance Fact Sheet Trichlorethene Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 27, < VM&P Naphtha NIOSH Pocket Guide to Chemical Hazards VM&P Naphtha. National Institute for Occupational Safety and Health Website. NIOSH. Accessed September 27, < Total Xylene Toxic Substance Fact Sheet Xylenes Agency for Toxic Substance and Disease Registry Website. ATSDM, Accessed September 29, < The Registry of Toxic Effects of Chemical Substances: Ligroine. National Institute for Occupational Safety and Health Website. NIOSH. Accessed September 27, < 41

42 APPENDIX A Viking Terrace Apartments - POST RENOVATION BUILDING TESTING DATA Vikings Terrace, Worthington Minnesota Building Test Data Unit # Square feet sf # of Bedrooms # DUCT # AVG. Flow cfm Leakage at 25 pa cfm Leakage at 25 pa (fixed) cfm AVG. Percent leakage as found % 67% 59% 80% 92% 69% 56% 94% 66% 73% Percent leakage fixed % 45% 42% 62% 77% 56% Leakage at 50 pa cfm Leakage at 50 pa (fixed) cfm AVG. Percent leakage as found (50 Pa.) % 86% 122% 138% 103% 83% 132% 99% 109% Percent leakage fixed (50 Pa.) % 90% 116% 103% Supply Pressure pa Return Pressure pa Return Inlet pa VENTILATION FLOWS # Ventilation IN (ahu) cfm Ventilation requirement (ASHRAE) cfm AVG. Ventilation as percent of ASHRAE % 64% 63% 66% 63% 0% 49% 63% 58% 64% 31% 56% 69% 54% Ventilation requirement (Minnesota single family) cfm Ventilation as percent of Minnesota single family % 36% 36% 38% 36% 0% 28% 36% 33% 36% 17% 32% 40% 31% Ventilation IN (+ bath) cfm Ventilation IN (+ kitchen) cfm AVG. Ventilation OUT (bath) cfm Ventilation OUT (kitchen high) cfm Ventilation out percent of fan rating % 20% 48% 63% 58% 58% - 34% 78% 47% 23% 57% 54% 49% Ventilation OUT (kitchen low) cfm PRESSURES # Bedroom 1 pa Exhaust Flows with window open 2"(To get to 3 pa.) cfm Bedroom 2 pa Bedroom 3 pa Unit # PRESSURES WITH SEALED INTAKE 1.4 AVG. to hall (ahu) pa (0.09) to hall (+ bath) pa (0.99) to hall (+ kitchen) pa (1.71) UNIT NOTES *exterior kitchen damper stuck closed *range hood has interior vent GENERAL NOTES *Center unit kitchen and bath exhaust is stacked vertically * Only 3rd floor, center units have back dampers on kitchen range hoods *Floor area=8582 sf, TOTAL building area=25,746 sf

43 APPENDIX A Viking Terrace Apartments - POST RENOVATION BUILDING TESTING DATA Unit # Square feet sf # of Bedrooms # Unit # DUCT Flow cfm Leakage at 25 pa cfm Leakage at 25 pa (fixed) cfm AVG. Percent leakage as found % 56% 50% 106% 64% 69% Percent leakage fixed % Leakage at 50 pa cfm Leakage at 50 pa (fixed) cfm AVG. Percent leakage as found (50 Pa.) % 82% 75% 155% 95% 102% Percent leakage fixed (50 Pa.) % Supply Pressure pa Return Pressure pa Return Inlet pa Ventilation IN (ahu) cfm Ventilation requirement (ASHRAE) cfm Ventilation as percent of ASHRAE % 53% 69% 74% 76% 74% 117% 95% 109% 82% 118% 81% 94% 87% Ventilation requirement (Minnesota single family) cfm Ventilation as percent of Minnesota single family % 30% 40% 42% 43% 42% 66% 55% 62% 47% 68% 46% 53% 50% Ventilation IN (+ bath) cfm Ventilation IN (+ kitchen) cfm AVG. Ventilation OUT (bath) cfm Ventilation OUT (kitchen high) cfm Ventilation out percent of fan rating(kitchen high) % 59% 62% 28% 26% 23% 22% 94% 92% 74% 84% 59% 50% 56% Ventilation OUT (kitchen low) cfm "0" PRESSURES # AVG. Bedroom 1 pa Bedroom 2 pa Bedroom 3 pa Unit # PRESSURES WITH SEALED INTAKE AVG. to hall (ahu) pa (0.05) to hall (+ bath) pa (1.33) to hall (+ kitchen) pa (4.53) UNIT NOTES *exterior kitchen damper stuck closed *range hood has interior vent GENERAL NOTES *Center unit kitchen and bath exhaust is stacked vertically * Only 3rd floor, center units have back dampers on kitchen range hoods *Floor area=8582 sf, TOTAL building area=25,746 sf

44 APPENDIX B Viking Terrace Apartments - ENERGY AND WATER USE ANALYSIS The Center for Sustainable Building Research, UMN Authors: William Weber, and Patrick Smith This report is an analysis of the water and energy use of Viking Terrace Apartments, which compares pre and post renovation consumption patterns based on utility billing. PROJECT BACKGROUND The Viking Terrace Apartments project is a rehab of 60 units of housing originally built in The rehab of the apartments was a pilot project for the Minnesota Green Communities and utilized Enterprise s Green Communities Criteria (version 1) to set goals for the project for water and energy efficiency. The criteria were also used to establish targets for unit ventilation and provided prescriptive measures to improve air quality through material and finish selection. The Viking Terrace complex consists of three buildings with a total of 60 units (1440: 12 units, 1450: 24 units and 1460: 24 units). The rehab was carried out in phases beginning in March of 2006 with the 1440 building and concluding in March 2007 with the completion of The energy efficiency improvement at Viking Terrace includes installation of a geothermal heating and cooling system. The geothermal ground loop is a vertical well field located on site. Heating, cooling and ventilation are provided to each individual unit via a small air handler in each unit which is connected to the central system (a two pipe system configuration) for the delivery of either hot (heating season) or cold (cooling season) water. Fresh air is draw directly into the air individual units via the air handler. Each unit has a programmable thermostat. Exhaust air is removed by a kitchen hood and bathroom exhaust fans. In addition to the mechanical improvements the envelope of the building was also upgraded. All windows were replaced with high performance windows (U-value 0.32; SHGC 0.31). Insulation was added to the exterior walls (R-value 11 existing plus 7.5 added) and the roof assembly (R-value 48). These upgrades and improved air sealing resulted in a low air leakage rate of Pa (compare Minnesota code for single family of Pa). Water efficiency upgrades were made by replacing fixtures with the improved performance. Dual flush toilets were installed. They use 1.0 gpf for a half flush, and 1.6 gpf for a full flush. Low flow fixtures were used in the bathroom (0.5 gpm) and kitchen sinks (1.5 gpm); and the showerhead (2.0 gpm). The clothes washers are low water using averaging 18 gallons per cycle. 1 csbr-wgw.7/29/09

45 TOTAL ENERGY CONSUMPTION The total combined electric and natural gas energy use at Viking Terrace Apartments was 2,303,219 kbtu or 39.7 kbtu/sf yr for a year of operation post renovation (October 2007 thru September 2008). This represents a 45% 1 reduction in total energy use, resulting in an estimated 14% reduction in CO 2 emissions related to energy consumption. The energy and CO 2 reductions are not symmetrical due to a shift in energy source from natural gas to electricity generated by a combination of wind (10%), hydro (30%), and coal (60%) for heating and cooling. figure 1: Viking Terrace Energy Intensity per square foot The projects energy use is shown in comparison to the 2030 Challenge benchmarks. The current 2030 challenge goal of 50% reduction results in an energy use of 25.4 kbtu/sf yr. This target is set for residential projects with 5 or more units in the Midwest region. Differentiation of energy use intensity by end use can not be determined due to overlapping end use from the same sources. Electricity use combines household (plug loads), heating, cooling and ventilation energy. Viking terrace used 1,352,419 kbtu or 23.3 kbtu/sf yr of electricity. Natural gas is used for domestic hot water heating and serves as a back up for space heating. Viking terrace used 969,816 kbtu or 16.7 kbtu/sf yr of natural gas. DETAILED ENERGY CONSUMPTION ANALYSIS By examining in the changes in energy consumption and use pattern from pre renovation to post renovation at Viking Terrace, it is possible to determine how the building is consuming energy. Natural Gas In the building retrofit, the heating fuel was switched from natural gas to electricity utilizing a ground source heat-pump. This significantly decreases and flattens the natural 1 Energy use savings estimate is not adjusted for weather or heating degree days. 2 csbr-wgw.7/29/09

46 gas consumption of the apartments, which is metered only at the building level. Figure 2 shows the natural gas consumption before and after the project. The natural gas post renovation is for domestic hot water only (natural gas back-up for heating did not fire during this period). figure 2: Viking Terrace natural gas use pre and post renovation. Electricity The individual unit electricity exhibits a much greater winter load post-renovation, and a reduced summer load. This is expected due to the shift of heating loads to electricity. Figure 3 shows the pre versus post-renovation average electricity consumption for units in building As can be seen, the post renovation building uses significantly more unit-metered electricity during the winter, but has a lower summer peak than prerenovation. The decrease in summer energy use is attributable to the improved windows, insulation and increased cooling efficiency of the geothermal which replaced through wall AC units. figure 3: Viking Terrace 1450 average unit electricity use pre and post renovation 3 csbr-wgw.7/29/09

47 Cost The cost of energy at Viking Terrace has shifted dramatically, away from the natural gas as the primary heating fuel and onto the electricity of the units. This results in a 20% decrease in the total energy cost, but a 21% increase in electricity costs. This result sin a net decrease in cost due to the price of electricity verses natural gas. Unit electricity bills had a 3% decrease, even with the addition of the heating load. Figure 4 shows the building meter s electricity usage before and after the renovation. As can be seen, there is a significant winter electricity load, with a much lower usage in the summer. figure 4: Viking Terrace building meter electricity consumption pre and post renovation Individual units at Viking Terrace saw an average of 3% decrease in their energy costs between pre- and post-renovation conditions (normalized for today s dollars). The apparent exception to the overall decrease is the average cost for three bedroom units, this could be due to the small sample size, that includes the two highest energy using units at $600 and $531 per year. The energy improvements and shift of responsibility for heating cost to the tenants decreased owner direct cost of energy by 43%. Viking Terrace Average Unit Energy Cost a number of units pre-renovation post renovatoin Number of bedrooms 1 22 $ $ $ $ $ $ a Pre-renovatoin is reported in adjusted dollars (*1.1024). table 1: Viking Terrace average unit utility cost Air Infiltration The pre-and post-renovation energy consumption profiles suggests that air infiltration due to the stack effect is the primary cause of energy loss. Examining the factors that 4 csbr-wgw.7/29/09

48 determine the energy use of a unit, the square footage, external wall area and floor (first, second, and third) are most influential factors. Solar access does not appear to be a major contributor, possibly due to the new windows low solar heat gain coefficient. Figure 5 shows post-renovation electricity use in The floor by floor consumption levels for stacked units shows higher energy use in the summer on the top floors. The second, middle floor shows median energy use for summer and winter, while the bottom floor uses relatively more energy in the winter and less in the summer. This use pattern is consistent with stack effect driving air exchange. The amount of exterior area is highly correlated with energy use in general, square footage of the units and number of bedrooms also highly correlate with energy consumption. figure 5: Viking Terrace electricity use for bedroom units floor by floor WATER Total water use post renovation was gallon/person/day (g/p/d) at Viking Terrace during the period, or 2,344,000 gallons with a residential population of 150. Indoor water use was estimated at g/p/d based on estimated sewer usage during the same period. Historic building population data was not available so a comparison to pre-renovation levels was not calculated. 5 csbr-wgw.7/29/09

49 figure 6: Viking Terrace water use per person post renovation as compared to national average Water costs decreased to 72% of their pre-renovation levels. Historic data for sewer costs and usage was not available. A reduction in sewer demand and cost is likely proportionate with the reduction in water costs. METHODOLOGY To estimate the energy consumption of a multi-family residential building, it is necessary to estimate the energy consumption of empty units using available data as the buildings are rarely fully occupied for a year. This is most notable for unit electricity consumption, though buildings that sub-meter natural gas may also necessitate a similar methodology. The consumption of other utilities, such as potable water, are compared on a per-capita basis and do not need to be estimated for the entire building. The energy consumption of building may change based on the number of occupied units depending on the design of the heating systems. To ensure that the building-wide utility bills are compared accurately, same-year data was compared and the R-squared value was examined to see if there was a correlation between the number of occupants and the building wide natural gas consumption, for the pre-renovation condition. The R-squared value between population difference and energy consumption difference for the same period between years was very low ( ). This implies that the building energy consumption varies very little according to population, and does not need adjustment even though the building was not completely occupied during this time. The same is true for the individual electrical consumption post-renovation, adjusted for HDD. There are several possible unit attributes that could determine the energy efficiency of a unit in a multi-family building. These include number of residences, floor of the unit, square footage of the unit, total outside area, solar radiation impacting the exterior walls and windows (which is determined by which face of the building the unit is located on with regard to south). An analysis of the occupied units in Viking Terrace apartments shows that the two factors most dominant in the total electricity consumption are the floor and the number of bedrooms (the respective R-squared values of and 0.93). The 6 csbr-wgw.7/29/09