Case Study: CBT Architects - Building Performance Modeling
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FITCHBURG STATE UNIVERSITY Building Performance Modeling Energy Reduction Strategies October 27, 2011 Liam O’Sullivan Chad Reilly Alfred Wojciechowski Presenters architecture interior design urban design boston, ma usa
description
CBT Architects present how they are integrating IES building performance analysis into their design process using the Fitchburg State Science Project as an example for this Case Study. This an interesting insight into how this architectural firm is going about incorporating early stage analysis into their processes, BIM and working in a more integrated manner with the engineer. The presentation is based on one given to a group from the Harvard Business School’s facilities and construction department.
Transcript of Case Study: CBT Architects - Building Performance Modeling
FITCHBURG STATE UNIVERSITY
Building Performance Modeling
Energy Reduction Strategies
October 27, 2011
Liam O’Sullivan
Chad Reilly
Alfred Wojciechowski
Presenters
architectureinterior designurban design
boston, ma usa
agenda
part 1: cbt – tools + process
a. softwareb. products
part 2: fitchburg state science projecta. overview of the building designb. the players in building performance
part 3: collaboration – team + processa. mep engineerb. commissioning agentc. energy modeling consultant
part 4: cbt – ies + process
total cost savings / lessons learned
fsu project overview
• 105,425 total square feet – 55,625 addition – 49,800 renovation• LEED silver targeted (state mandated)• new wing: biology (8 labs), chemistry
(3 labs), student lounges• existing wing: physics (3 labs), geology
(2 labs), classrooms, faculty offices• on main campus road and terminus of
main quad
fsu site location
fsu site context
biology labs + support
shared sciences
physics labs + classrooms
fsu elevations
cbt process evidence based design + building information modeling (bim)
3D visualization – design communication coordination• sketchup, photoshop, revit, navisworks, physical models
data rich – capture and retrieve information• revit
simulations – building components and elements• ecotect, ies
3D visualization sketchup + photoshop
data rich revit – schematic design building area + program analysis
3D visualization sketchup + cad + photoshop
3D visualization revit – bim model
• structure• floor slab• plumbing• fire protection
• hvac•
electrical
• walls + ceiling• furniture +
cabinetry
3D visualization revit – bim model
• completed building• combined revit
model
3D visualization revit – bim model
simulations ecotect
simulations ies (integrated environmental solutions)
collaboration
team + process
energy reduction collaboration
core design team members
• overall coordination• building performance modeling
• develop systems• maintain code compliance
• traditional energy modeling• identify energy reduction
opportunities
• advise end user on operations• identify energy reduction
opportunities
cbt – architect
mechanical, electrical + plumbingengineer
energy modeling consultant
commissioning agent
mep design systems development (sd phase)
commissioning energy + water savings strategies report (dd phase)
• building description + proposed mep systems
• proposed energy + water savings strategies
• labs21 benchmarking analysis
• ashrae integrating energy strategies in accademic lab facilities
• case studies• bridgewater state college• umass amherst new science
building• yale university new engineering
building• national renewable energy lab
key components
commissioning comparative analysis (dd phase)
energy modeling analysis + recommendations (dd phase)
collaboration outstanding issues matrix (dd phase)
building performance modeling integrated, evidence based design
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Date: Mon 01/Dec to Wed 31/Dec
Heating plant sensible load: 301 Lab Organic (all_fins_dec.aps) Heating plant sensible load: 314 Nursing / Indust (all_fins_dec.aps)
energy modeling verification report
cbt
ies + process
specifics of building performance modeling
main topics: • site conditions• building envelope• building facade• daylight harvesting• artificial lighting• natural ventilation
revit generated model ies generated model
2 3 M a y 1 8 : 0 0
site solar shading analysis of adjacent hill
23 May – 6:00 PM
zone of influence
building envelope insulation – wall
• wall insulation (base case)• 2 ½ʺ rigid insulation• U-value = 0.062 BTU/hr∙ft²∙ºF
• wall insulation (20% above code)• 4ʺ rigid insulation• U-value = 0.043 BTU/hr∙ft²∙ºF• additional $0.85/sf over 14,920 sf
• hypothesis• more insulation will result in lower energy use and operating costs
building envelope insulation – wall
• results• increasing insulation beyond 2 ½ʺ resulted in very minimal savings and made no
difference in envelope performance
• net first cost savings to NOT use 4ʺ thick insulation: $12,500
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Date: Sun 20/Jul to Sat 26/Jul
Cooling plant sensible load: 96 rooms (increase wall to 4 inch insulation.aps) Cooling plant sensible load: 96 rooms (base_case.aps)
heating plant sensible loads during winter solstice
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Date: Sun 21/Dec to Sat 27/Dec
Heating plant sensible load: 96 rooms (increase wall to 4 inch insulation.aps) Heating plant sensible load: 96 rooms (base_case.aps)
cooling plant sensible loads during summer solstice
MARGINALLY REDUCED HEATING LOAD NEGLIGIBLY IMPROVED COOLING LOAD
2 ½ʺ insulation
4ʺ insulation
$290/ yr.
building envelope insulation – roof
• hypothesis• more insulation will result in lower energy use and operating costs
• roof insulation (20% above code)• 6ʺ minimum rigid insulation• U-value = 0.040 BTU/hr∙ft²∙ºF• additional $1.50/sf over 31,750 sf
• roof insulation (base case)• 5ʺ minimum rigid insulation• U-value = 0.048 BTU/hr∙ft²∙ºF
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Date: Wed 24/Dec
Heating plant sensible load: 96 rooms (increase roof insulation.aps) Heating plant sensible load: 96 rooms (base_case.aps)
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Date: Sun 20/Jul
Cooling plant sensible load: 96 rooms (increase roof insulation.aps) Cooling plant sensible load: 96 rooms (base_case.aps)
heating plant sensible loads (dec. 24th) cooling plant sensible loads (july 20th)
MARGINALLY REDUCED HEATING LOAD
5ʺ insulation
6ʺ insulation
NEGLIGIBLY IMPROVED COOLING LOAD
building envelope insulation – roof
• results• increasing insulation to code (5ʺ minimum thickness) resulted in savings of
$4,260 annually• increasing insulation to 6ʺ resulted in very minimal savings and made no
difference in envelope performance• minor heating savings achieved during the winter are offset during remaining
seasons when it is beneficial to have less insulation trapping heat within the building
• net first cost savings to NOT use insulation thicker than 5ʺ: $47,500
$205/ yr.
modeling results of upgrading roof insulation to 20% above code(6ʺ minimum thickness) – new addition roof
modeling results of upgrading roof insulation to code (5ʺ minimum thickness)and to 20% above code (6ʺ minimum thickness) – condike roof
$4,260/ yr.+$186/ yr.
5ʺ insulation6" insulation
6" insulation
HEATING LOAD DOMINANCE
building envelope heating + cooling loads
annual heating and cooling plant sensible loads
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Date: Wed 01/Jan to Wed 31/Dec
Cooling plant sensible load: 96 rooms (increase wall to 4 inch insulation.aps) Heating plant sensible load: 96 rooms (increase wall to 4 inch insulation.aps)
building envelope glass
• high perfomance glass• ¼ʺ viracon glazing• ½ʺ air space cavity• ¼ʺ clear float glazing• U-value = 0.28 BTU/hr∙ft²∙ºF• solar heat gain coefficient = 0.35
• super high perfomance glass • ¼ʺ solarban glazing• ½ʺ air space cavity• ¼ʺ clear float glazing• U-value = 0.28 BTU/hr∙ft²∙ºF• solar heat gain coefficient = 0.27• additional $25/sf over 8,008 sf
• hypothesis• super high performance glass will lower operating costs and be worth the initial
cost increase
• cooling loads: reduced by 45%• heating loads: increased by 3.9%• heating loads are much greater than cooling loads,
so the modest increase in heating loads more than cancels the energy savings from cooling
Delta = 4,000 MBTU / year (0.59% of max)
building envelope glass
ies virtual environment model and components
high performanceglass
super highperformance glass
building envelope glass
• results• decrease in solar heat gain coefficient results in requirement for additional reheat
energy that more than offsets the electrical savings• in a new england climate, with minimal summer course offerings, super high
performance glass resulted in equal or poorer performance in overall energy use• net first cost savings to NOT use super high performance glass: $200,000
- $2,457/ yr.modeling results of super high performance glass
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Date: Sun 21/Dec to Sat 27/Dec
Heating plant sensible load: 96 rooms (upgrade to solarban.aps) Heating plant sensible load: 96 rooms (base_case.aps)
INCREASE IN HEATING LOAD
heating plant sensible loads during winter solstice
high performance glass
super high performance glass
building facade overhangs at glass entry pavilion
• hypothesis• increasing the depth of the overhangs will reduce cooling loads
1 foot overhangs
7 foot overhangs
building facade overhangs at glass entry pavilion
• results• 9,804,000 BTU of cooling saved annually • significant annual cooling cost savings to use 7 foot overhangs
cooling plant sensible loads during summer cycle
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Date: Mon 21/Jul
Cooling plant sensible load: lobby level 2 & 310A Atrium / Lounge (base_case_all_shades.aps)
Cooling plant sensible load: lobby level 2 & 310A Atrium / Lounge (base_case_no_shades.aps)
cooling plant sensible loads during single day peak time (july 21st)21% reductionin cooling load
SIGNIFICANT COOLING LOAD REDUCTION
7 foot overhangs
1 foot overhangs
7029 BTU/hr.8918 BTU/hr.
7 foot overhangs1 foot overhangs
facade and roof plant loads during peak heating periods
greenhouse – no shades
entry lobby – horizontal shades
Cooling load
Heating load
Heating load
greenhouse glass entrypavilion
building facade exterior shading – solar simulation model
west facing lab 301
east facing lab 314
horizontal shade
vertical shade
“frame”
sun path diagram –building orientation
ies software – model
climate data –sun movement
building facade exterior shading – horizontal fins
• hypothesis• increasing the depth of the horizontal fins will reduce cooling loads
12" deep horizontal fins
36" deep horizontal fins
building facade exterior shading – horizontal fins
• results• increasing horizontal fins beyond 12ʺ resulted in very minimal electrical energy
savings due to reductions in cooling• decreasing the amount of solar gain within the building resulted in an increase
in reheat energy, which more than offsets the electrical savings• net first cost savings to NOT use 36ʺ deep horizontal fins: $65,000
annual cooling plant sensible loads (ies software generated graph)
opportunityfor
savingsWEST FACING LAB
EAST FACING LAB
building facade exterior shading – vertical fins
8" deep vertical fins
36" deep vertical fins
• hypothesis• increasing the depth of the vertical fins will reduce cooling loads
building facade exterior shading – vertical fins
• results• increasing vertical fins beyond 8ʺ resulted in very minimal electrical energy
savings due to reductions in cooling• decreasing the amount of solar gain within the building resulted in an increase
in reheat energy, which more than offsets the electrical savings• net first cost savings to NOT use 36ʺ deep vertical fins: $68,000
heating plant sensible loads (dec. 23rd)
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Date: Tue 23/Dec
Heating plant sensible load: 301 Lab Organic (dec_vert_fins.aps) Heating plant sensible load: 314 Nursing / Indust (dec_vert_fins.aps)
Heating plant sensible load: 301 Lab Organic (dec_vert_fins_36.aps) Heating plant sensible load: 314 Nursing / Indust (dec_vert_fins_36.aps)
INCREASE IN HEATING LOAD
8ʺ vertical fins
36ʺ vertical fins
building facade exterior shading – summary data
no shades no shades no shades no shades
horizontal shades horizontal shades horizontal shades horizontal shades
vertical shades vertical shades vertical shades vertical shades
horiz. and vert. shades horiz. and vert. shades horiz. and vert. shades horiz. and vert. shades
1.899
1.694
1.669
1.251 2.342
2.272 1.357
1.491
MAY COOLING DEC HEATING
heating and cooling plant sensible loads comparing shade layouts
daylight harvesting ies software – radiance analysis
daylight levels (fc) 53.669 increasedpercentage area 44.7 increasedabove threshold (fc)
daylight harvesting internal light shelves
effective natural light penetration into space decrease in natural light penetration into space
• results• net first cost savings to NOT use light shelves: $687,000
no light shelves light shelves
daylight harvesting windows and depth
• analysis• how deep does effective natural light penetrate into the classrooms and labs?
effective natural light penetration into space
ON ONOFF
daylight harvesting windows and depth
• results• net savings: in 1/3 of the space, artificial lighting can be turned off through the
use of sensors to maximize natural daylight harvesting• significantly lower operational costs
28% of daytime lighting needs in the lab can be met with no light shelves
artificial lighting light layouts and lamping – base design (linear)
1.4 Watts/Square Foot allowable
typical classroom at condike
base design: 3.71 W/SF(2.31 W/SF over)• hypothesis
• through foot candle targets modeling, first cost and energy costs can be reduced
31 fc (low)171 fc (high)102 fc (avg)
artificial lighting light layouts and lamping – revised design (gridded)
revised design: .94 W/SF(0.46 W/SF under)
• results• effective and even lighting levels achieved with a 30% watts
per square foot lighting power density reduction• net savings:
• first cost: $100,500• operating costs: $10,500/year• potential utility company incentives: $16,000/year
• comparison• design development layout based on electrical engineer, manufacturing data, and
architectural decisions versus prioritizing energy reduction, architectural layouts, and "effective and even lighting" levels
8 fc (low)54 fc (high)27 fc (avg)
natural ventilation glass enclosed stairways
dynamic modeling of envelope, air movement, and shading• hypothesis
• natural ventilation can provide comfort and reduce operating costs versus a mechanical cooling system
natural ventilation glass enclosed stairways – improving temperatures
improvement bynatural ventilation
unventilated stair temp
naturally ventilatedstair temp
exterior temp
unventilated stair temp
naturally ventilatedstair temp
exterior temp
exterior temp
naturally ventilatedstair temp
unventilated stair temp
improvement by natural ventilation
temperature changes in stairways throughout the school year (ies software generated graphs)
natural ventilation glass enclosed stairways – increasing thermal comfort
Natural ventilation reduces theoccurrence of temperaturesabove 72ºF during operating
hours from more than 20% of thetime to less than 10% of the time
in the south stair.
• results• elimination of 4 tons of cooling by NOT using air conditioning units• first cost savings to naturally ventilate stairways: $34,500
stair temperatures by hour without natural ventilation
stair temperatures by hour with natural ventilation
project savings
site conditionsneighborhood hillside
building envelopeglassinsulation – wallinsulation – roof
building facadeexterior shading – vertical finsexterior shading – horizontal finsoverhang at glass entry pavilion
daylight harvestingwindows and depthinternal light shelves
artificial lightinglight layouts and lamping
natural ventilationglass enclosed stairways
total first cost savingstotal operating cost savings
n/a
$200,000$12,500$47,500
$68,000$65,000n/a
n/a$687,000
$100,500
$34,500
$1,500,000
$34,300 per year
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lessons learned
1. multi disciplines should participate together to inform low operating goals first costs
2. ʺrules of thumbʺ and manufacturer‘s data are too general ; simulation results should be specific to your project in your location
3. do continuous experimentation through the design phases to maximize effective decision making
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