Raising the Bar: A Comparison Study of Iowa s Current and Proposed Energy Code

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Raising the Bar: A Comparison Study of Iowa’s Current and Proposed

Energy Code

Julia Gauthier, LEED AP BD+C

Jeanne Huntsman, AIA, LEED Green Associate The Weidt Group

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

Not intended to be a comprehensive

evaluation of how to meet new code

requirements



Study inspired by impact of code changes on

CNC program projects



Views expressed do not represent the state of

Iowa, code officials, or the utilities directly



We are not code officials



This study was completed in May 2012

Special statements

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

The new code



Analysis and results



Building type results



Summary



Conclusion

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Code Comparison

Raising the Bar

2009 IECC

(ASHRAE 90.1-2007)

change to

2012 IECC

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The New Code



Details of updates for ASHRAE 90.1-2010

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Summary of updates for ASHRAE 90.1-2010

The New Code

Building envelope

roof/wall insulation no change (except metal buildings) skylights major change

Heating, ventilation & air conditioning

equipment control major change required equipment major change required efficiencies major change Service hot water no changes Power/plug load control major change Lighting

controls major change automatic daylighting controls major change

lighting design varies by space type Motor efficiency minor change

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Design Feature The Change Increased insulation for a

metal building

Code level assembly insulation values

increased from R-8.8 to R-14.5 for walls and R-15.4 to R-18.2 for roofs

Skylights Given certain criteria a minimum skylight fenestration area is required

Building Envelope

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A closer look…minimum skylight fenestration area

Building Envelope



A skylight is required in any

enclosed space in a building

that is four stories or less and:

 greater than 5,000 sq. ft.

 directly under a roof with a ceiling height over 15 ft

 is one of the following spaces:

 Example

 5,000 sq. ft. gymnasium in a two story high school with a ceiling height of 20 feet

 Skylights required?

 ASHRAE 90.1–2007: NO

 ASHRAE 90.1–2010: YES

office lobby Atrium distribution / sorting area non-refrigerated warehouse or storage gymnasium / exercise center convention

center automotive service

manufacturing

retail concourse transportation workshop

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Summary of Changes

HVAC

Design Feature The Change

Enclosed parking garage ventilation

CO sensor control will be required for garage ventilation fans

Multi-zone variable air volume (VAV) system ventilation

optimization control

appears to require occupancy sensor control of outside air to VAV boxes

(further interpretation needed to fully determine impact)

Hydronic variable flow systems almost all pumping systems to will require variable speed control

Exhaust air energy recovery heat recovery requirements based on percent OA and total supply air (required addition of heat recovery to three of eight buildings studied)

Kitchen/dining facilities require increased control or heat recovery if exhausting more than 5,000 cfm

Improved DX cooling efficiencies Code level DX cooling efficiencies increased 5%-15% depending on the size and heating type

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Design Feature The Change Variable Refrigerant Flow

(VRF) Systems

Code level efficiencies have been added. EER: 9.3 to 16.2

COP: 2.05 to 4.2 Water-to-water heat

pumps

Code level efficiencies have been added.

EER: 10.6 (water source) or 16.3 (groundwater) COP: 3.7 (water source) or 3.1 (groundwater) Chiller performance New emphasis on part-load performance, as

well as a Path A and a Path B. Path A: lower full load, higher part load. Path B: higher full load, lower part load

Computer Room Unit Code level efficiencies have been added. Utilizes a Sensible COP (SCOP). Differentiates downflow and upflow units

HVAC

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A closer look… exhaust air energy recovery

HVAC



Exhaust air energy recovery

required when the following

conditions are met:



Example



Air handling system providing

6,000 CFM of supply air, 35%

outside air

 Exhaust air energy recovery required?  ASHRAE 90.1 – 2007: NO  ASHRAE 90.1 – 2010: YES with at least 50% effectiveness Supply Air CFM Outside Air % >5500 30 - 40 >4500 40 - 50 >3500 50 - 60 >2000 60 - 70 >1000 70 - 80 >0 > 80

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Design Feature The Change Service hot water No significant changes

Power Automatic plug load control, automatic

receptacle control, at least 50% of all 125 volt, 15 and 20 ampere, receptacles in private

offices, open offices and computer classrooms shall be controlled by an automatic control device

Service Hot Water and Power

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Summary of Changes

Lighting

Design Feature The Change

Lighting control any automatic control device shall be manual on or only automatically on to 50%

Space control all controlled lighting shall have at least one

control step between 30% and 70% in addition to all off, dual level switching is required

Parking garage lighting control

parking garage lighting is required to have automatic control to reduce power of each

luminaire by 30% when no activity is detected for 30 minutes

Automatic daylighting controls for primary sidelighted areas

when sidelighted area is equal to or exceeds 250 sf, the lamps must be controlled with a

photosensor and contain at least one control step that is between 50% and 70% and another to no greater than 35%

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Design Feature The Change Automatic daylighting

controls for toplighting

when the daylight area under the skylights or roof monitors exceeds 900 s.f., the lamps must be

controlled with a photosensor and contain at least one control step that is between 50% and 70% and

another to no greater than 35% Lighting power

densities using the space-by-space method

reduced lighting power densities for most spaces. Incorporation of room cavity ratio (RCR), which

allows for increased lighting power density allowances based on room geometry

(unique per building, further study needed) Individual lighting

power allowances for building exteriors

reduced lighting power allowances for most exterior areas

Summary of Changes

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A closer look…automatic daylighting (side lighted)

Lighting



When primary sidelighted

area in an enclosed space

equals or exceeds 250 sf the

lamps shall be controlled by

at least one multi-level

photocontrol. The

multi-level photocontrol must

reduce electric lighting in

response to available light

with at least one control

step between 50% and 70%

and another control step no

greater than 35%.



Example



100,000 sq. ft. office building

with typical open office

operation, open office has

side lighted space greater

than 250 sq. ft.

 Automatic stepped

daylighting control required?  ASHRAE 90.1–2007: NO

 ASHRAE 90.1–2010: YES two-step control

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Building type selection

Analysis and Results



Sample of Iowa Commercial New Construction (CNC)

program participants



Alliant Energy, Black Hills Energy and MidAmerican Energy

program participants

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Ten test buildings

Analysis and Results

Type Heating Cooling Air Flow Bldg

SF

Garage SF

Middle/High School Gas boiler Air-cooled chiller Variable air volume 94,500 0

Middle/High School Electric Boiler Water-loop heat pump Constant volume 94,500 0

College Classroom Gas boiler Water-cooled chiller Variable air volume 80,000 0

College Classroom District Heating District Cooling Variable air volume 80,000 0

Office Gas furnace Air-cooled DX Variable air volume 45,000 0

Office Electric Boiler Water-loop heat pump Constant volume 45,000 0

Multi-family Gas furnace Air-cooled DX Constant volume 60,000 0

Multi-family Electric boiler Water-loop heat pump Constant volume 60,000 0

Retail Gas furnace Air-cooled DX Constant volume 66,400 3,600

Transportation/ Public Works

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Procedure

Analysis and Results



Current Energy Code



Created a current

2009 IECC energy model

baseline for each

building using the

prescriptive path of

ASHRAE 90.1-2007



New Energy Code



Created a 2012 IECC

energy code baselines

incorporating building

specific changes found

in ASHRAE 90.1 – 2010

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Results - total energy use in kBtu per square foot

Analysis and Results

0 20 40 60 80 100 120 140 160 120 107 57 69 80 81 87 83 92 147 95 ₈₇ 52 62 75 75 86 82 ₇₁ 75

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

Observations



The weighted average of all sample buildings is

18% less energy when built to the new code



Transportation/public works indicates the largest

change (49%) due to more stringent controls of

heated garages



Multi-family is expected to use about the same as

current code because new code does not impose

many restrictions on residential buildings, test

buildings did not have garages

Results – Annual Energy Costs

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Results – Annual Energy Costs

Analysis and Results

$0 $50,000 $100,000 $150,000 $200,000 $250,000

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

Observations



Iowa average energy costs



The weighted average of all

sample buildings is

21% lower

annual

energy costs



Transportation/public works has the

largest reduction



Multi-family has the smallest change in annual

energy costs

Results – Annual Energy Costs

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Building Type Results

Analysis and Results



Middle/high school



College classroom



Office



Multi-family



Retail



Transportation/public

works

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Middle/High School (electric system)

Analysis and Results



Building summary



Heat source: electric

boiler



Cool source: water loop

heat pump



Airflow: constant volume



Building area: 94,500 sq.

ft.



Primary space types:

 Classroom, gym

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Middle/High School (electric system)

Analysis and Results



Skylights required in gym



Two step automated

daylighting required near

windows and

under skylights



Occupancy sensor control of

lights in most spaces



Reduced lighting power

densities



VFDs on circulation pumps



Exhaust air energy recovery

kBtu therm kWh kW Energy Cost

Old Code (today) 106.8 7,410 2,720,379 687.4 $214,133 New Code 87.3 7,410 2,184,876 532.1 $173,114 Difference 19.5 0 535,503 155.3 $41,019

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College Classroom (gas system)

Analysis and Results



Building summary



Heat source: gas boiler



Cool source:

water-cooled chiller



Airflow: variable air

volume



Building area: 80,000 sq.

ft.



Primary space types:

 Classroom, laboratory,

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College Classroom (gas system)

Analysis and Results



Two step automated

daylighting required near

windows **



Occupancy sensor control of

lights in most spaces **



Reduced lighting power

densities **



VFDs on circulation pumps



Occupancy sensor control of

plug load



** Contributes to increased gas

usage

Old code (today) 56.6 19,220 723,935 290.9 $70,370 New code 51.8 20,860 566,956 251.0 $59,619 Difference 4.8 -1,640 156,979 39.9 $10,751

(28)

Office (gas system)

Analysis and Results



Building summary



Heat source: gas furnace



Cool source: air-cooled

DX



Airflow: variable air

volume



Building area: 45,000 sq.

ft.



Primary space types:

 Open office, private

(29)

Office (gas system)

Analysis and Results



Two step automated

daylighting required near

windows **



Occupancy sensor control of

lights in most spaces **



Reduced lighting

power densities

**



Occupancy sensor control of

plug load



**Contributes to increased gas

usage

Old code (today) 80.1 17,800 522,984 200.2 $53,872 New code 75.2 19,620 405,918 175.6 $46,315 Difference 4.9 -1,820 117,066 24.6 $7,557

(30)

Multi-Family (electric system)

Analysis and Results



Building summary



Heat source: electric



Cool source: water loop

heat pump



Airflow: constant volume



Building area: 60,000 sq.

ft.



Primary space types:

 Apartment

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Multi-Family (electric system)

Analysis and Results



Least impacted building type

studied



Two step automated

daylighting required near

windows in non-residential



Dual level switching of lights

in non-residential areas



Reduced lighting power

densities in non-residential



Occupancy sensor control of

plug load



Increased cooling efficiencies

Old Code (today) 83.4 19,260 897,923 199.7 $83,729 New Code 82.3 19,260 877,730 196.5 $82,182

Difference 1.1 0 20,193 3.2 $1,547

(32)

Retail (gas system)

Analysis and Results



Building summary



Heat source: gas furnace



Cool source: air-cooled

DX



Airflow: constant volume



Building area: 66,400 sq.

ft.

 additional garage area: 3,600 sq. ft.



Primary space types:

 Sales floor, auto

(33)

Retail (gas system)

Analysis and Results



Skylights required



Two step automated

daylighting required near

windows and under skylights



Reduced lighting

power densities



Exhaust air energy

recovery required



CO control of vehicle storage

ventilation fans

Old Code 91.5 33,930 867,840 265.6 $92,808 New Code 71.2 24,000 746,063 222.0 $75,767 Difference 20.3 9,930 121,777 43.6 $17,041

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Transportation/Public Works (gas system)

Analysis and Results



Building summary



Heat source: gas furnace



Cool source: air-cooled

DX



Airflow: constant volume



Building area: 41,000 sq.

ft.

 additional garage area: 108,800 sq. ft.



Primary space types:

(35)

Transportation/Public Works (gas system)

Analysis and Results



Most impacted building type

studied



Skylights required



Two step automated

daylighting required by

windows and under skylights



Reduced lighting power

densities



Exhaust air energy

recovery required



CO control of vehicle storage

ventilation fans

Old code (today) 147.3 187,460 1,011,955 259.9 $222,985 New code 74.5 88,740 689,134 185.3 $121,651 Difference 72.8 98,720 322,821 74.6 $101,334

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

The new code impacts different buildings differently



Depending on the space types and system characteristics the

code may play a more significant role in shaping the design

Analysis and Results Summary

18% 8% _6% 1% 22% 49% 19% 15% _14% 2% 18% 45%

Percent Change OLD to NEW Code

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

As expected, the new code – 2012 IECC (ASHRAE 90.1

– 2010) – raises the bar for a minimally code compliant

building



Implementation of the new code will reduce building

energy usage by approximately 20% on average



If the goal is increased energy reduction from current

levels, the new energy code accomplishes the goal



If the goal is increased energy reduction beyond the

new code, additional steps will need to be taken

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Summary



So what does

it all mean?



It’s not just a

jumble of numbers

and pulling out

(39)

Going Beyond Code

 Start early, consider the

energy efficiency implications of decisions made during Pre-Design

 Massing

 Orientation

 Window/wall ratio

 Investigate several mechanical systems and life-cycle costs  What was once cost-prohibitive

may no longer be

 Expand upon the code requirements

 If the code says automatic

daylight control required for 1,000 sf, can the design allow for 2,000 sf?

 If the code says 50% plug load must be controlled by occupancy sensors, can 75% be controlled?