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

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 01

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Load

(B

tu/h

)

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

Sun Mon Tue Wed Thu Fri Sat Sun

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Load

(B

tu/h

)

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

Sun Mon Tue Wed Thu Fri Sat Sun

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Lo

ad

(B

tu/h

)

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

00:00 06:00 12:00 18:00 00:00

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340000

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Loa

d (B

tu/h

)

Date: Wed 24/Dec

Heating plant sensible load: 96 rooms (increase roof insulation.aps) Heating plant sensible load: 96 rooms (base_case.aps)

00:00 06:00 12:00 18:00 00:00

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300000

250000

200000

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50000

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Loa

d (B

tu/h

)

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

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan

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Lo

ad

(B

tu/h

)

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

Sun Mon Tue Wed Thu Fri Sat Sun

450000

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Load

(B

tu/h

)

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

00:00 06:00 12:00 18:00 00:00

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Load

(B

tu/h

)

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)

00:00 06:00 12:00 18:00 00:00

13000

12000

11000

10000

9000

8000

7000

6000

5000

4000

3000

2000

1000

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Lo

ad

(B

tu/h

)

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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