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RETROCOMMISSIONING A SMALL COMMERCIAL BUILDING TO ACHIEVENET-ZERO ENERGY
Lucas WitmerDept of Energy amp Mineral Engineering
The Pennsylvania State University263 MRL Building
University Park PA 16802LWitmerpsuedu
Andrew PoerschkeIBACOS Inc
2214 Liberty AvePittsburgh PA 15222
andrewpoerschkegmailcom
Jeffrey R S BrownsonDept of Energy amp Mineral Engineering
The Pennsylvania State University265 MRL Building
University Park PA 16802solarpowerpsuedu
ABSTRACT
The Bayer EcoCommercial Buildings ConferenceCenter (ECB CC) located in Pittsburgh PA formerlythe Penn State 2009 Solar Decathlon home (NaturalFusion) has undergone an extensive retro-commissioning process to achieve net-zero energyperformance This work has been focused on adaptingthe building to its current location and use schedulethrough active control strategies while remediatingissues such as infiltration derived from moving thebuilding several times A comprehensive energysimulation has been developed in the Transient SystemSimulation tool (TRNSYS) that incorporates all of thebuildingrsquos energy systems in their current configurationInnovative systems and features of the building include
Fig 1 Photo of the Bayer MaterialScience EcoCommer-cial Building Conference Center[1]
photovoltaics solar hot water phase change materialsductless mini-split heatpumps floor radiators and highlevels of insulation in the walls and ceiling Extensivedata has been collected on the building over a yearcycle including weather energy consumption andenvelope performance and has been used to benchmarkthe model over the past year followed by TMY dataforecasting ongoing net-zero energy performance for thefuture The modeling results show the largest areas ofimpact on the energy budget Recommendations aremade regarding the critical issues to focus on whenundertaking a retrocommissioning projects targetingthe goal of net-zero energy
1 INTRODUCTION
The US Department of Energy (DOE) and theNational Renewable Energy Lab (NREL) have hostedfive Solar Decathlon competitions since 2002 Eachdecathlon is an international competition to designbuild and operate a solar powered home Following the2009 Solar Decathlon competition the Penn Stateentry was acquired by Bayer MaterialScience to becomethe first North American showcase for theEcoCommercial Building program[1] On May 26 2010following the construction and set-up of the buildingafter moving it from the competition location inWashington DC the EcoCommercial Building
1
Conference Center (ECBCC) was officially unveiled atthe Bayer MaterialScience headquarters in Pittsburgh
With all of the complexities involved in renovating abuilding for something other than its intended usemoving a building several times and dealing withunique systems designed by students that are bothprototypes and intended to push the boundaries ofengineering it should be apparent that significantretrocommissioning was necessary to target the goal ofa net-zero energy building
2 RETROCOMMISSIONING
Retrocommissioning is the first step to assess whatenergy systems are doing compared with what theyshould be doing and step by step guides have been laidout by groups including the EnergyStar program[2]Through this process HVAC controllers are checked forthe best schedules and setpoints the building is testedfor infiltration and appropriate insulation and energygeneration systems are evaluated for performance Theend goal of the work performed here is a net-zeroenergy building
21 HVAC Controls
As designed the building had two ductless mini-splitsthat were to be operated solely by a remote Thesystems did not have scheduled programmablecapabilities This style of operation is acceptable for anoccupant-controlled residential building howeverpotential energy savings were lost with the building asa commercial conference center New thermostats wereinstalled and programmed to utilize a night time andweekend set-back schedule realizing significant energysavings
22 Building Envelope
Figure 2 shows IR thermography that was used toidentify locations for additional air sealing Theseincluded areas around door and window frames Figure3 shows a blower door test device that was empolyed toidentify additional areas to target The blower doortest revealed a significant amount of leakage throughthe building envelope with an ACH50 rating of 1174A large portion of this leakage was found to be aroundthe frames of the movable southern door systemhighlighting the need for these types of door systems tobe precisely installed Figure 4 shows smoke testingthat revealed a number of previously unknown leakageareas including seals around the skylight frames andlow voltage wiring boxes
Fig 2 Thermal imaging of the outside of the buildingshowing heat loss through door and window frames
Fig 3 Photo of the blower door test device installed ina doorway
Fig 4 Photo of smoke testing revealing infiltration
2
23 On-site Energy Conversion
After the initial 6 months of operation it was identifiedthat the PV system was performing at less than 50its rated capacity rendering the buildings net-zeroenergy goal out of reach Efforts to identify the causeof this revealed that half of the panels on the mainarray had an open circuit and that one third of thepanels on the secondary array were not correctly wiredinto the junction box This was a symptom of theremoval of the PV system for the buildingrsquostransportation After the move the system was notreconnected carefully with attention to detail
3 MODELING
A whole building energy model was developed using theTransient System Simulation tool (TRNSYS)[3] Figure5 shows the simplified building in Trimble Sketchupdesigned using the TRNSYS3D plugin that is based onOpenStudio For the purpose of using the detailedradiation mode in TRNBuild the building was splitinto 24 convex zones The interior surfaces seenthrough the windows in Figure 5 are mostly virtualsurfaces as the building consists of two primary zoneseach with a ductless mini-split heat pump system forclimate control
Fig 5 Screenshot of the building for energy modeling
To model the glycerin-based phase change materialhoused within most of the exterior walls the energymodel includes a place-holder material with a highthermal capacitance that behaves in a similar mannerstoring thermal energy At the time of modeldevelopment a model for this phase change materialwas not readily available Further the floor in most ofthe building contains water storage for thermal massjust beneath the floor in between the joists This wasmodeled in a similar manner
Infiltration rates were applied to the building in
accordance with the blower door test resultsVentilation was applied with an air-to-air energyrecovery ventilation unit that was readily availablewithin TRNSYS Heat exchange rates were applied permanufacturerrsquos specifications The windows weremodeled as double pane argon-filled windows with alow solar heat gain coefficient matching those on thebuilding The photovoltaic arrays on the two roofs aswell as the awning were lumped as one horizontal arrayand performance was benchmarked against real energyconversion data In reality the two main arrays consistof Solyndra panels and have different properties basedon the underlying roofs and slight differences in tiltwhile the small awning array tracks on one axis fromeast to west The modeled approximation was veryclose to the actual production over the whole year
0 1 2 3 4 5 6 7 8
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
Hea
ting
(kW
)
Time (One Selected Week Mid-Winter)
Modeled Measured
0 1 2 3 4 5 6
Sunday Monday Tuesday Wednesday Thursday Friday SaturdayCoo
ling
(kW
)
Time (One Selected Week Mid-Summer)
Modeled Measured
0
1
2
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
PV (k
W)
Time (Same Week as Above)
Modeled Measured
Fig 6 Top A typical heating week Middle A typicalcooling week Bottom A typical week of PV generation
Figure 6 shows a typical week in heating modefollowed by a typical cooling week Examining the loadprofiles for the building shows a lack of base load in theevenings and higher spikes at the beginning andthroughout the day Future work will focus on a closermatch of the model to the measured data There aretimes throughout the year when unpredictable energyuse occurred These incidences are taken into accountby focusing on the annual net use and bench-markingagainst the total energy consumed The bottom graphin Figure 6 shows a very close match to the PVgeneration curve profiles
For a period of one year from June 3 2011 to June 22012 the building model was compared againstmeasured energy use data During this time thebuilding used 4348 kWh while the bench-marked modelshowed consumption of 4413 kWh This is a predictionof 15 more energy consumption than reality The PV
3
0
1000
2000
3000
4000
5000
6000
June 3 2011
Winter (Heating Season)Summer (Cooling Season)
Summer (Cooling Season)
June 2 2012
Cum
ulat
ive
Ener
gy (k
Wh)
Time (One Year)
Model and Data Results
TMY Consumed (5208 kWh)Model Consumed (4413 kWh) Actual Consumed (4348 kWh)TMY Generated (4400 kWh) Model Generated (4434 kWh)Actual Generated (4580 kWh)
Fig 7 Cumulative energy use and generation for one year
generation systems produced 4580 kWh while themodel predicted production of 4434 kWh This is aprediction of 32 less than reality The result is aslightly conservative model that over predicts energyuse while under predicting energy production Duringthis period the building achieves a net-zero energybalance However the 2011 to 2012 winter inPittsburgh was abnormally temperate and thenet-zero or net-positive margin is very slim with theconservative model
Figure 7 shows the cumulative energy path from June 3to June 2 for both generation and consumption for themeasured data (2011-2012) bench-marked model andfinally the TMY model Running the bench-markedmodel with a typical meteorological year data file forPittsburgh PA the building and its users areestimated to use 5208 kWh per year while the PVsystem produces 4400 kWh per year This is anet-energy deficit of 808 kWh per year or 155 lessenergy than is needed to achieve net-zero energy statusCurrently the building is still undergoing variousretrocommissioning improvements including measuresagainst infiltration and windowdoor frame energy lossContinuing to reduce the energy consumed positionsthis building well for achieving net-zero
As a final recommendation if the building energyreduction process does not lower total energy use belowthe PV system production in its current configuration
a few additional PV panels or a reconfigured array withhigher efficiency panels should meet the necessaryrequirements The current PV array is horizontallymounted A slight tilt to the south would boost annualproduction potentially enough to meet demand
4 ACKNOWLEDGMENTS
The Pennsylvania State University the College of Earthand Mineral Sciences and the John and Willie LeoneFamily Department of Energy and Mineral Engineering
The US Department of Energy the NationalRenewable Energy Laboratory and the 2009 SolarDecathlon Competition
Bayer MaterialScience LLC
5 REFERENCES
(1) EcoCommercial Builing Network (2013) URLhttpecocommercial-building-networkcom
portfolio-view
net-zero-conference-center-usa (2) Energy Star(2007) Energy Star Buliding Manual URLhttpwwwenergystargoviabusinessEPA_BUM_
CH5_RetroCommpdf (3) Klein S A J A Duffie andW A Beckman (1976) ldquoTRNSYS A transientsimulation programsrdquo ASHRAE Trans 82 pp 623633
4
Conference Center (ECBCC) was officially unveiled atthe Bayer MaterialScience headquarters in Pittsburgh
With all of the complexities involved in renovating abuilding for something other than its intended usemoving a building several times and dealing withunique systems designed by students that are bothprototypes and intended to push the boundaries ofengineering it should be apparent that significantretrocommissioning was necessary to target the goal ofa net-zero energy building
2 RETROCOMMISSIONING
Retrocommissioning is the first step to assess whatenergy systems are doing compared with what theyshould be doing and step by step guides have been laidout by groups including the EnergyStar program[2]Through this process HVAC controllers are checked forthe best schedules and setpoints the building is testedfor infiltration and appropriate insulation and energygeneration systems are evaluated for performance Theend goal of the work performed here is a net-zeroenergy building
21 HVAC Controls
As designed the building had two ductless mini-splitsthat were to be operated solely by a remote Thesystems did not have scheduled programmablecapabilities This style of operation is acceptable for anoccupant-controlled residential building howeverpotential energy savings were lost with the building asa commercial conference center New thermostats wereinstalled and programmed to utilize a night time andweekend set-back schedule realizing significant energysavings
22 Building Envelope
Figure 2 shows IR thermography that was used toidentify locations for additional air sealing Theseincluded areas around door and window frames Figure3 shows a blower door test device that was empolyed toidentify additional areas to target The blower doortest revealed a significant amount of leakage throughthe building envelope with an ACH50 rating of 1174A large portion of this leakage was found to be aroundthe frames of the movable southern door systemhighlighting the need for these types of door systems tobe precisely installed Figure 4 shows smoke testingthat revealed a number of previously unknown leakageareas including seals around the skylight frames andlow voltage wiring boxes
Fig 2 Thermal imaging of the outside of the buildingshowing heat loss through door and window frames
Fig 3 Photo of the blower door test device installed ina doorway
Fig 4 Photo of smoke testing revealing infiltration
2
23 On-site Energy Conversion
After the initial 6 months of operation it was identifiedthat the PV system was performing at less than 50its rated capacity rendering the buildings net-zeroenergy goal out of reach Efforts to identify the causeof this revealed that half of the panels on the mainarray had an open circuit and that one third of thepanels on the secondary array were not correctly wiredinto the junction box This was a symptom of theremoval of the PV system for the buildingrsquostransportation After the move the system was notreconnected carefully with attention to detail
3 MODELING
A whole building energy model was developed using theTransient System Simulation tool (TRNSYS)[3] Figure5 shows the simplified building in Trimble Sketchupdesigned using the TRNSYS3D plugin that is based onOpenStudio For the purpose of using the detailedradiation mode in TRNBuild the building was splitinto 24 convex zones The interior surfaces seenthrough the windows in Figure 5 are mostly virtualsurfaces as the building consists of two primary zoneseach with a ductless mini-split heat pump system forclimate control
Fig 5 Screenshot of the building for energy modeling
To model the glycerin-based phase change materialhoused within most of the exterior walls the energymodel includes a place-holder material with a highthermal capacitance that behaves in a similar mannerstoring thermal energy At the time of modeldevelopment a model for this phase change materialwas not readily available Further the floor in most ofthe building contains water storage for thermal massjust beneath the floor in between the joists This wasmodeled in a similar manner
Infiltration rates were applied to the building in
accordance with the blower door test resultsVentilation was applied with an air-to-air energyrecovery ventilation unit that was readily availablewithin TRNSYS Heat exchange rates were applied permanufacturerrsquos specifications The windows weremodeled as double pane argon-filled windows with alow solar heat gain coefficient matching those on thebuilding The photovoltaic arrays on the two roofs aswell as the awning were lumped as one horizontal arrayand performance was benchmarked against real energyconversion data In reality the two main arrays consistof Solyndra panels and have different properties basedon the underlying roofs and slight differences in tiltwhile the small awning array tracks on one axis fromeast to west The modeled approximation was veryclose to the actual production over the whole year
0 1 2 3 4 5 6 7 8
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
Hea
ting
(kW
)
Time (One Selected Week Mid-Winter)
Modeled Measured
0 1 2 3 4 5 6
Sunday Monday Tuesday Wednesday Thursday Friday SaturdayCoo
ling
(kW
)
Time (One Selected Week Mid-Summer)
Modeled Measured
0
1
2
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
PV (k
W)
Time (Same Week as Above)
Modeled Measured
Fig 6 Top A typical heating week Middle A typicalcooling week Bottom A typical week of PV generation
Figure 6 shows a typical week in heating modefollowed by a typical cooling week Examining the loadprofiles for the building shows a lack of base load in theevenings and higher spikes at the beginning andthroughout the day Future work will focus on a closermatch of the model to the measured data There aretimes throughout the year when unpredictable energyuse occurred These incidences are taken into accountby focusing on the annual net use and bench-markingagainst the total energy consumed The bottom graphin Figure 6 shows a very close match to the PVgeneration curve profiles
For a period of one year from June 3 2011 to June 22012 the building model was compared againstmeasured energy use data During this time thebuilding used 4348 kWh while the bench-marked modelshowed consumption of 4413 kWh This is a predictionof 15 more energy consumption than reality The PV
3
0
1000
2000
3000
4000
5000
6000
June 3 2011
Winter (Heating Season)Summer (Cooling Season)
Summer (Cooling Season)
June 2 2012
Cum
ulat
ive
Ener
gy (k
Wh)
Time (One Year)
Model and Data Results
TMY Consumed (5208 kWh)Model Consumed (4413 kWh) Actual Consumed (4348 kWh)TMY Generated (4400 kWh) Model Generated (4434 kWh)Actual Generated (4580 kWh)
Fig 7 Cumulative energy use and generation for one year
generation systems produced 4580 kWh while themodel predicted production of 4434 kWh This is aprediction of 32 less than reality The result is aslightly conservative model that over predicts energyuse while under predicting energy production Duringthis period the building achieves a net-zero energybalance However the 2011 to 2012 winter inPittsburgh was abnormally temperate and thenet-zero or net-positive margin is very slim with theconservative model
Figure 7 shows the cumulative energy path from June 3to June 2 for both generation and consumption for themeasured data (2011-2012) bench-marked model andfinally the TMY model Running the bench-markedmodel with a typical meteorological year data file forPittsburgh PA the building and its users areestimated to use 5208 kWh per year while the PVsystem produces 4400 kWh per year This is anet-energy deficit of 808 kWh per year or 155 lessenergy than is needed to achieve net-zero energy statusCurrently the building is still undergoing variousretrocommissioning improvements including measuresagainst infiltration and windowdoor frame energy lossContinuing to reduce the energy consumed positionsthis building well for achieving net-zero
As a final recommendation if the building energyreduction process does not lower total energy use belowthe PV system production in its current configuration
a few additional PV panels or a reconfigured array withhigher efficiency panels should meet the necessaryrequirements The current PV array is horizontallymounted A slight tilt to the south would boost annualproduction potentially enough to meet demand
4 ACKNOWLEDGMENTS
The Pennsylvania State University the College of Earthand Mineral Sciences and the John and Willie LeoneFamily Department of Energy and Mineral Engineering
The US Department of Energy the NationalRenewable Energy Laboratory and the 2009 SolarDecathlon Competition
Bayer MaterialScience LLC
5 REFERENCES
(1) EcoCommercial Builing Network (2013) URLhttpecocommercial-building-networkcom
portfolio-view
net-zero-conference-center-usa (2) Energy Star(2007) Energy Star Buliding Manual URLhttpwwwenergystargoviabusinessEPA_BUM_
CH5_RetroCommpdf (3) Klein S A J A Duffie andW A Beckman (1976) ldquoTRNSYS A transientsimulation programsrdquo ASHRAE Trans 82 pp 623633
4
23 On-site Energy Conversion
After the initial 6 months of operation it was identifiedthat the PV system was performing at less than 50its rated capacity rendering the buildings net-zeroenergy goal out of reach Efforts to identify the causeof this revealed that half of the panels on the mainarray had an open circuit and that one third of thepanels on the secondary array were not correctly wiredinto the junction box This was a symptom of theremoval of the PV system for the buildingrsquostransportation After the move the system was notreconnected carefully with attention to detail
3 MODELING
A whole building energy model was developed using theTransient System Simulation tool (TRNSYS)[3] Figure5 shows the simplified building in Trimble Sketchupdesigned using the TRNSYS3D plugin that is based onOpenStudio For the purpose of using the detailedradiation mode in TRNBuild the building was splitinto 24 convex zones The interior surfaces seenthrough the windows in Figure 5 are mostly virtualsurfaces as the building consists of two primary zoneseach with a ductless mini-split heat pump system forclimate control
Fig 5 Screenshot of the building for energy modeling
To model the glycerin-based phase change materialhoused within most of the exterior walls the energymodel includes a place-holder material with a highthermal capacitance that behaves in a similar mannerstoring thermal energy At the time of modeldevelopment a model for this phase change materialwas not readily available Further the floor in most ofthe building contains water storage for thermal massjust beneath the floor in between the joists This wasmodeled in a similar manner
Infiltration rates were applied to the building in
accordance with the blower door test resultsVentilation was applied with an air-to-air energyrecovery ventilation unit that was readily availablewithin TRNSYS Heat exchange rates were applied permanufacturerrsquos specifications The windows weremodeled as double pane argon-filled windows with alow solar heat gain coefficient matching those on thebuilding The photovoltaic arrays on the two roofs aswell as the awning were lumped as one horizontal arrayand performance was benchmarked against real energyconversion data In reality the two main arrays consistof Solyndra panels and have different properties basedon the underlying roofs and slight differences in tiltwhile the small awning array tracks on one axis fromeast to west The modeled approximation was veryclose to the actual production over the whole year
0 1 2 3 4 5 6 7 8
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
Hea
ting
(kW
)
Time (One Selected Week Mid-Winter)
Modeled Measured
0 1 2 3 4 5 6
Sunday Monday Tuesday Wednesday Thursday Friday SaturdayCoo
ling
(kW
)
Time (One Selected Week Mid-Summer)
Modeled Measured
0
1
2
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
PV (k
W)
Time (Same Week as Above)
Modeled Measured
Fig 6 Top A typical heating week Middle A typicalcooling week Bottom A typical week of PV generation
Figure 6 shows a typical week in heating modefollowed by a typical cooling week Examining the loadprofiles for the building shows a lack of base load in theevenings and higher spikes at the beginning andthroughout the day Future work will focus on a closermatch of the model to the measured data There aretimes throughout the year when unpredictable energyuse occurred These incidences are taken into accountby focusing on the annual net use and bench-markingagainst the total energy consumed The bottom graphin Figure 6 shows a very close match to the PVgeneration curve profiles
For a period of one year from June 3 2011 to June 22012 the building model was compared againstmeasured energy use data During this time thebuilding used 4348 kWh while the bench-marked modelshowed consumption of 4413 kWh This is a predictionof 15 more energy consumption than reality The PV
3
0
1000
2000
3000
4000
5000
6000
June 3 2011
Winter (Heating Season)Summer (Cooling Season)
Summer (Cooling Season)
June 2 2012
Cum
ulat
ive
Ener
gy (k
Wh)
Time (One Year)
Model and Data Results
TMY Consumed (5208 kWh)Model Consumed (4413 kWh) Actual Consumed (4348 kWh)TMY Generated (4400 kWh) Model Generated (4434 kWh)Actual Generated (4580 kWh)
Fig 7 Cumulative energy use and generation for one year
generation systems produced 4580 kWh while themodel predicted production of 4434 kWh This is aprediction of 32 less than reality The result is aslightly conservative model that over predicts energyuse while under predicting energy production Duringthis period the building achieves a net-zero energybalance However the 2011 to 2012 winter inPittsburgh was abnormally temperate and thenet-zero or net-positive margin is very slim with theconservative model
Figure 7 shows the cumulative energy path from June 3to June 2 for both generation and consumption for themeasured data (2011-2012) bench-marked model andfinally the TMY model Running the bench-markedmodel with a typical meteorological year data file forPittsburgh PA the building and its users areestimated to use 5208 kWh per year while the PVsystem produces 4400 kWh per year This is anet-energy deficit of 808 kWh per year or 155 lessenergy than is needed to achieve net-zero energy statusCurrently the building is still undergoing variousretrocommissioning improvements including measuresagainst infiltration and windowdoor frame energy lossContinuing to reduce the energy consumed positionsthis building well for achieving net-zero
As a final recommendation if the building energyreduction process does not lower total energy use belowthe PV system production in its current configuration
a few additional PV panels or a reconfigured array withhigher efficiency panels should meet the necessaryrequirements The current PV array is horizontallymounted A slight tilt to the south would boost annualproduction potentially enough to meet demand
4 ACKNOWLEDGMENTS
The Pennsylvania State University the College of Earthand Mineral Sciences and the John and Willie LeoneFamily Department of Energy and Mineral Engineering
The US Department of Energy the NationalRenewable Energy Laboratory and the 2009 SolarDecathlon Competition
Bayer MaterialScience LLC
5 REFERENCES
(1) EcoCommercial Builing Network (2013) URLhttpecocommercial-building-networkcom
portfolio-view
net-zero-conference-center-usa (2) Energy Star(2007) Energy Star Buliding Manual URLhttpwwwenergystargoviabusinessEPA_BUM_
CH5_RetroCommpdf (3) Klein S A J A Duffie andW A Beckman (1976) ldquoTRNSYS A transientsimulation programsrdquo ASHRAE Trans 82 pp 623633
4
0
1000
2000
3000
4000
5000
6000
June 3 2011
Winter (Heating Season)Summer (Cooling Season)
Summer (Cooling Season)
June 2 2012
Cum
ulat
ive
Ener
gy (k
Wh)
Time (One Year)
Model and Data Results
TMY Consumed (5208 kWh)Model Consumed (4413 kWh) Actual Consumed (4348 kWh)TMY Generated (4400 kWh) Model Generated (4434 kWh)Actual Generated (4580 kWh)
Fig 7 Cumulative energy use and generation for one year
generation systems produced 4580 kWh while themodel predicted production of 4434 kWh This is aprediction of 32 less than reality The result is aslightly conservative model that over predicts energyuse while under predicting energy production Duringthis period the building achieves a net-zero energybalance However the 2011 to 2012 winter inPittsburgh was abnormally temperate and thenet-zero or net-positive margin is very slim with theconservative model
Figure 7 shows the cumulative energy path from June 3to June 2 for both generation and consumption for themeasured data (2011-2012) bench-marked model andfinally the TMY model Running the bench-markedmodel with a typical meteorological year data file forPittsburgh PA the building and its users areestimated to use 5208 kWh per year while the PVsystem produces 4400 kWh per year This is anet-energy deficit of 808 kWh per year or 155 lessenergy than is needed to achieve net-zero energy statusCurrently the building is still undergoing variousretrocommissioning improvements including measuresagainst infiltration and windowdoor frame energy lossContinuing to reduce the energy consumed positionsthis building well for achieving net-zero
As a final recommendation if the building energyreduction process does not lower total energy use belowthe PV system production in its current configuration
a few additional PV panels or a reconfigured array withhigher efficiency panels should meet the necessaryrequirements The current PV array is horizontallymounted A slight tilt to the south would boost annualproduction potentially enough to meet demand
4 ACKNOWLEDGMENTS
The Pennsylvania State University the College of Earthand Mineral Sciences and the John and Willie LeoneFamily Department of Energy and Mineral Engineering
The US Department of Energy the NationalRenewable Energy Laboratory and the 2009 SolarDecathlon Competition
Bayer MaterialScience LLC
5 REFERENCES
(1) EcoCommercial Builing Network (2013) URLhttpecocommercial-building-networkcom
portfolio-view
net-zero-conference-center-usa (2) Energy Star(2007) Energy Star Buliding Manual URLhttpwwwenergystargoviabusinessEPA_BUM_
CH5_RetroCommpdf (3) Klein S A J A Duffie andW A Beckman (1976) ldquoTRNSYS A transientsimulation programsrdquo ASHRAE Trans 82 pp 623633
4
