Nonresidential HVAC Stakeholder Meeting Space and Water ...h-m-g.com/T24/NonresHVAC/2011_04_08_presentations/WaterandSpace Heating... · ACM algorithms based on PIER MF central DHW

California Statewide Utility Codes and Standards Program

1

Nonresidential HVAC

Stakeholder Meeting – Space

and Water Heating CASE Study

Heschong Mahone Group, Inc.

Energy Solutions

April 8, 2011

CALIFORNIA STATEWIDE UTILITIES CODES AND STANDARDS PROGRAM

4/8/2011 CA Utilities 2013 Title 24 Stakeholder Meeting for Proposed Code Changes

ACM Update-Water & Space Heating, VRF

● Summary of current code requirements

● Summary of code change proposals

● Typical practice

● Data/findings

● Specifics of code change proposals

● Remaining data collection and analysis

2 2

by topic


Water & Spacing Heating


Current Code Requirements ● DHW Performance Algorithms

● ACM algorithms based on PIER MF central DHW study

● Distribution system pipe heat loss – with controls & branch

● Standard and default plumbing designs

● Hydronic Space Heating Algorithms

● Consistent with DHW pipe heat loss model

● ACM Standard Designs

● Wall furnace and space heating boiler

● Air duct assumption

● Pipe Insulation

● Improvement - Table 123-a update

● Include pipes in unconditioned buildings (Table 100)

● VRF – not addressed in 2008 Title 24

3




Typical Practice

● Performance calculation method reflecting common

design practice

● Central DHW distribution with recirculation loop

● Hydronic heating distribution system is similar to DHW

distribution pipe heat loss

● Standard Designs

● Fan type wall furnace is as common as gravity type wall furnace

● Hot water boilers are used for hydronic heating in most buildings

● Air ducts are in conditioned spaces in most MF buildings

● Pipe Insulation

● Cost effectiveness is the barrier for more insulation

● VRF – market penetration is low

4




Summary of code change proposals

● DHW Performance Algorithms

● Distribution system pipe heat loss – controls, plumbing, branch

● Hydronic Space Heating Algorithms

● Follow DHW pipe loss algorithms, optional capability required

● ACM Standard Designs

● Heating equipment efficiency

● Res ACM: Wall-furnace standard design – fan type

● Boiler – hot water boiler, not steam boiler

● Air duct in MF building – standard design same as proposed (no credit)

● Pipe Insulation

● Update mandatory insulation thickness - Table 123–a

● Cover pipes in unconditioned buildings

● VRF – 2008 Title 24 Optional Capability

5




Data / Findings – PIER DHW Research

● Field performance study of 30+ MF buildings

● Energy flow analysis

● Performance Modeling

6

Water Heater

Losses Distribution Losses

End-Use

Energy 30%

30%

Branch

Losses* Recirculation

Loop Losses Include pipe inside and

outside of dwelling units




Data / Findings – Pipe Heat Loss Model

● System model includes two heat transfer modes

with consideration of transition

● Pipe heat transfer with HW flow

● UA, water temp & flow, ambient temp

● Pipe without HW flow - cool down

● UA and pipe/water thermal capacity

7




Data / Findings –Model Validation

● Based on actual building DHW recirculation loop

configurations

● Compare modeled vs. measured HWR Temp, and

energy losses

8

2

3

4

9

5

6

7

1 10 11 12

8

1 2

3

4

10

5

7

8

9

11

12 13

6




9

Data / Findings – Model Validation Result

SFDMeasured

(Btu/day)

Modeled

(Btu/day)

Measured

reduction

(%)

Modeled

reduction

(%)

Measured

(Btu/day)

Modeled

(Btu/day)

Measured

reduction

(%)

Modeled

reduction

(%)

Measured

(Btu/day)

Modeled

(Btu/day)

Measured

reduction

(%)

Modeled

reduction

(%)

CONT Pump 608,711 608,711 - - 639,732 643,487 - - 1,875,663 1,879,417 - -

Temp Mod 600,697 582,695 1.3% 4.3% 633,433 616,266 1.0% 4.2% 1,958,764 1,941,597 -4.4% -3.3%

Timer 507,048 461,656 17% 24% 600,803 562,822 6.1% 13% 1,732,428 1,694,446 7.6% 10%

Demand 215,483 191,328 65% 69% 411,903 453,556 36% 30% 1,423,628 1,465,281 24% 22%

Total Hot Water EnergyRecirculation Flow Heat Loss Recirculation Loop Heat Loss

HW Draw

SFD

Hot Water

Energy

(Btu/day)

Modeled

savings

(%)

Measured

(Btu/day)

CONT Pump 1,879,417 - 1,235,931

Temp Mod 1,871,511 0.4% 1,325,331

Timer 1,816,132 3.4% 1,131,625

Demand 1,749,959 6.9% 1,011,725

w/o Flow Variation

Recirculation loop loss represent 34% Total hot water energy

Total hot water energy = Hot water draw + recirculation loop loss




10

DHW ACM – Proposal Overview

● Recirculation Loop Pipe Heat Loss

● Flow and temperature dependent

● Recirculation system controls

● Hydronic system pipe heat loss

● Standard and Default Distribution

Plumbing Layout

● Branch Pipe Heat Loss




DHW ACM – Hourly Heating Load

Distribution pipe heat loss – Existing DHW ACM

11

● Recirculation Loop ● Plumbing layout based on

building geometry

● HW Draw patterns; or HW flow

rates for hydronic heating

● HW temp: 135F for HW; vary

for hydronic heating & Control

Hourly

Standard

End Use

Hourly

Adjusted

Recovery Load

Distribution

Loss

Multiplier

Solar

Savings

Multiplier

Hourly

Recirculation

Distri. Loss

Hourly

Jacket

Loss

Implement monthly variation

Inside dwelling unit:

DLMk =1 + (SDLMk-1)*DSMk

DSMk =1 for MF

SSMk should be applied to HRDLk

as well; however, it depends on

how SSF is rated

● Branch ● Depend on HSEUk

should be a multiplier

to HSEUk

● Modify DLMk to include

heat loss from

branches outside of

dwelling unit

Proposed Improvement




DHW ACM – Pipe Heat Loss

Proposed Recirculation Distribution Pipe Heat Loss

12

Hourly ambient temperature

for pipe section, n

Hourly average water

temperature for pipe section, n

Average water temperature

during pump-off period

Average water temperature

during pump-on period

● Assess hourly average pipe temperature to calculate heat loss

- Replace the table of UL with explicit calculation

● Average pipe temperature is weighted between two modes, which

depend on control schedule

Weighting factor depending

on control schedule

● Each control strategy has a 24-hour schedule




13

DHW ACM – Hourly Control Schedule

TEMPERATURE MODULATION

p Pump

off

Time

TS TS

With cont.

monitoring

0 0 120 115

0 0 120 115

0 0 120 115

0 0 120 115

0 0 125 120

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 135 130

0 0 125 120

DEMAND CONTROL

p Pump

off

Time

TS

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

t 1-t 135

Continuous Pumping

Hour p Pump

off

Time

TS TS

With cont.

monitoring

1 0 0 135 130

2 0 0 135 130

3 0 0 135 130

4 0 0 135 130

5 0 0 135 130

6 0 0 135 130

7 0 0 135 130

8 0 0 135 130

9 0 0 135 130

10 0 0 135 130

11 0 0 135 130

12 0 0 135 130

13 0 0 135 130

14 0 0 135 130

15 0 0 135 130

16 0 0 135 130

17 0 0 135 130

18 0 0 135 130

19 0 0 135 130

20 0 0 135 130

21 0 0 135 130

22 0 0 135 130

23 0 0 135 130

24 0 0 135 130



4/8/2011 CA Utilities 2013 Title 24 Stakeholder Meeting for Proposed Code Changes 4/11/2011

14

DHW ACM – Plumbing Design

Hydronics heating and Central DHW ACM update

Supply

Return

Boiler

Room

n=1 n=2 n=3

n=6 n=5 n=4

● Current ACM requires user input of pipe length for three

pipe sections

● Proposed changes

● Supply and return each has three sections –

● Unconditioned, conditioned, underground,

● Return pipes behave dramatically different from supply pipes under controls

● ACM generate default system layout to check/adjust user input

(details to be discussed after ACM algorithms)




DHW ACM – Default Plumbing Design

Existing ACM algorithms – only rely on user input

15

• Building Story, floor area

• Number of apartment/guest room

• Boiler room Location

• Number of Loops

• Supply and Return Loop section

locations and length

USER INPUT

• Recirculation loop path

• Branch length and number

• Pipe diameters (Follow UPC)

• Pipe insulation thickness

ACM Generate Standard &

Default Loop Configuration

User

Input

Design

Default

Design

Compare

Standard

Design

Proposed

Design




16

User Inputs

Return Recirculation Pipe

Section #1

30

Section #2 Section #3

10

Supply Recirculation Pipe

Section #1

10

Section #2 Section #3

30

Uncondition

ed Space

2”

Conditione

d Space

2”

4 stories / 2 loops

Conditioned

Space

1”

Uncondition

ed Space

3/4”

Supply Return

Loop 1 80 ft 80 ft

Loop 2 80 ft 80 ft

Total 320 ft

Generate ACM

Default

Total Length <

90% ACM

Default?

Yes No

Keep

user

input

Default Design

Adjust

user

input

Increase total length

to ACM default

DHW ACM – Default Plumbing Design




DHW ACM – Standard Recirc. Design

17

● Dual loop design

● Boiler room near the middle of the building

● Any floor - 1st floor, garage, roof, middle floor

● Smaller pipe diameters less surface area

● Smaller temp drop (not included in savings calc.)

● Verification

● Res: HERS

● NR: follow Appendix NA2

● NR Field Verification & Diagnostic

Test Procedures

Standard Design




18

● Existing – pressure drop and pump power

● Based on IAPMO Uniform Plumbing Code

# of Dwelling Units Line Size

1 0.75

2 1

3 – 4 1.25

5 – 7 1.5

8 – 20 2

21 – 42 2.5

43 – 67 3

68 – 100 3.5

101 – 144 4

DHW ACM – Pipe Sizing




19

DHW ACM – Branch Heat Loss

● Pipe Heat Loss

● Pipe heat loss during usage = (GPHk/Numbranch)∙ ∙Cp∙ Tbranch

● tbranch: follow recirculation loop formula

● Water Waste

● Water waste = NumWait∙Cp ∙ ∙(1.4∙Volbranch) ∙(Tsupply,branch-Tcoldwater)

1.4∙Volbranch : 40% more – pipe heat capacity, non-mixing, waiting




20

DHW ACM – Branch NumWait

● NREL HW draw event tool

● Random hot water draw patterns

●

Number of unit

on branch




21

DHW ACM – Hydronic Heating

● Move from Optional Capability to required

● Hydronic system fuel consumption calculation

PL:

Hourly pipe loss rate

RI:

Rated input of the gas

water heater

Exis

tin

g

Pro

po

sed




22

● Only consider pipe loss in unconditioned space

● Return temperature is lower than supply temp

Conditioned

Space

HourlyLoad Supply Return

TS,end TR,start

DHW ACM – Hydronic Heating Heat Loss




Wall Furnace – Current Standard Designs

● Fan types are more efficient than gravity type

● Federal efficiency standards

23




Wall Furnace – LCC Analysis

● Fan type only cost effective in the climate zone 16 - No change

24

Climate Zone PV Saving/Unit Incremental Cost LCC

1 $212 $514 $302

2 $227 $514 $287

3 $102 $514 $412

4 $120 $514 $394

5 $53 $514 $461

6 $9 $514 $505

7 $4 $514 $510

8 $17 $514 $497

9 $9 $514 $505

10 $44 $514 $470

11 $257 $514 $257

12 $241 $514 $273

13 $189 $514 $325

14 $254 $514 $260

15 $16 $514 $498

16 $576 $514 -$62




Boiler – Current Standard Designs

● EnergyPro use steam boiler efficiency as

standard design heating equipment

● Federal boiler efficiency standards (AFUE)

25

Effective

January 1,

1992

Effective

Septemper 1,

2012

Gas steam boilers

with single phase

electrical supply

75% 80%

Gas hot water

boilers with single

phase electrical

supply

80% 82%




Boiler – Proposed Code Language

● Specify hot water boiler as the standard design

heating equipment

● NR ACM

● Table N2-15 – System #3 Description

Heating System: Gas hot water boiler





26




● MF buildings have similar duct assumption as

single-family buildings

Air Ducts – Current Standard Design (Res)

27

Air Dis Table R3-1 – Summary of Standard Design HVAC System

Proposed Design Standard Design

Heating System Cooling System Heating System Cooling System Detailed Specifications

Through-the-wall heat pump Same equipment as proposed design with no air distribution ducts

Equipment efficiency determined by CEC Appliance Efficiency Regulations

Gas wall furnace with our without ducts and/or circulation fan

Any Same equipment as proposed design with no air distribution ducts

Split system AC with air distribution ducts

Any other electric heat including electric resistance, water source heat pump, etc.

Any Split system heat pump with air distribution ducts

SEER per Package D

Verified refrigerant charge (prescriptive requirement)

No credit for sizing

No credit for cooling coil airflow

No credit for reduced fan power

All other gas heating Any Split system air conditioner with gas furnace and air distribution ducts.

Note: The standard design cooling system is also used for the proposed design if the proposed design has no air conditioning




Air Ducts – Proposed Code Language (Res)

● Update Table R3-30 in Res ACM

28

Propose Design Standard Design

Heating Cooling Heating Cooling Detailed Specifications

Through-the-wall heat pump Same equipment as proposed design with no air

distribution ducts

Equipment efficiency

determined by CEC

Appliance Efficiency

Regulations Gas wall furnace

with or without ducts

and/or circulation fan

Any Same equipment as

proposed design with no

air distribution ducts

Same equipment as

proposed design

with no air

distribution ducts

Any other electric

heat including

electric resistance,

water source heat

pump, etc.

Any Split system heat pump with air distribution ducts;

For multi-family buildings, air distribution duct

length in unconditioned space is the same as the

proposed design

SEER per Package D

Verified refrigerant

charge (prescriptive

requirement)

No credit for sizing

No credit for cooling

coil airflow

No credit for reduced

fan power

All other gas heating Any Split system air conditioner with gas furnace and

air distribution ducts.

For multi-family buildings, air distribution duct

length in unconditioned space is the same as the

proposed design

Note: The standard design cooling system is also used for the proposed design if the proposed design has no air

conditioning




● Hydronic heating system may be compared to split system

with central furnace with duct loss

● The “Other” category compared to ducted systems

Air Ducts – Current Standard Design (NR)

29




● Table N2-14 – System #1 and System #2

Descriptions

Ducts: For ducts installed in unconditioned buffer spaces or outdoors

as specified in § 144(k), the duct system efficiency shall be as

described in Section 2.5.3.18. For All residential including

hotel/motel guest room, duct configurations shall be the same

as proposed.

Air Ducts – Proposed Code Language (NR)

30




● Not required for unconditioned building

● Res Mandatory follows the same requirements

Pipe Insulation – Current Requirements

31




● Increase insulation by 0.5 inch for all cases

● Cost effective (negative LCC) in all climate zones

Pipe Insulation – LCC (100% duty)

32

Fluid

Temperature

Range (°F)

Conductivity

Range

(Btu-inch/hr/

sqft/ °F)

Nominal Pipe Diameter (inches)

0.5 0.75 1 1.25 2 2.5 4 5 6 8

LCC ($/ft) – 30 year gas TDV

Above 350 0.32-0.34 -$9.0 -$13 -$0.26 -$1.0 -$3.0 -$1.5 -$4.2 $0.00

251-350 0.29-0.31 -$4.23 -$6.5 -$1.19 $0.33 -$1.2 -$2.2 -$4.9 $0.00

201-250 0.27-0.30 -$7.76 -$11 -$0.88 -$1.5 -$3.3 -$2.2 -$4.8 -$3.6

141-200 0.25-0.29 -$9.82 -$14 $0.02 -$0.4 -$1.8 -$2.6 -$5.2 $4.7

105-140 0.24-0.28 -$3.42 -$5.2 -$0.39 -$0.8 -$2.0 -$2.8 -$5.2 $4.7

DHW >105 0.24-0.28 -$4.19 -$6.2 -$0.76 -$0.2 -$2.3 -$0.1 -$1.3 $4.7




● Increase insulation by 0.5 inch for all cases

● Not cost effective (positive LCC) in all climate zones

Pipe Insulation – LCC (50% duty)

33

Fluid

Temperature

Range (°F)

Conductivity

Range

(Btu-inch/hr/

sqft/ °F)

Nominal Pipe Diameter (inches)

0.5 0.75 1 1.25 2 2.5 4 5 6 8

LCC ($/ft) – 30 year gas TDV

Above 350 0.32-0.34 -$2.3 -$4.2 $2.1 $1.7 $0.8 $2.0 $0.9 $0.00

251-350 0.29-0.31 -$0.3 -$1.4 $1.3 $2.4 $1.7 $1.3 $0.2 $0.00

201-250 0.27-0.30 -$2.4 -$4.0 $1.1 $0.8 $0.0 $1.0 $0.0 -$3.6

141-200 0.25-0.29 -$3.4 -$5.4 $1.5 $1.3 $0.8 $0.5 -$0.5 $4.7

105-140 0.24-0.28 -$0.6 -$1.5 $1.0 $0.8 $0.4 $0.1 -$0.7 $4.7

DHW >105 0.24-0.28 -$1.0 -$2.0 $0.8 $2.7 $1.9 $1.8 $1.5 $4.7




● Table 123-A DHW Pipes

● “Service water-heating systems (recirculating

sections, all piping in electric trace tape systems,

and the first 8 feet of piping from the storage tank for

nonrecirculating systems, and the first 8 feet of

branch piping from recirculation loops)”

● Increase pipe insulation by 0.5 inch for DHW pipes

● Space Heating – only for selected climate

zones

Pipe Insulation – Proposed Change

34




● DHW pipe in unconditioned buildings

Pipe Insulation – Proposed Change

35




● Statewide energy savings analysis

● Finalize insulation requirements for space

heating pipes

Remaining Analysis

36



Water & Space Heating, VRF

37

QUESTIONS & COMMENTS

?

Documents

Nonresidential HVAC Stakeholder Meeting Space and Water ...h-m-g.com/T24/NonresHVAC/2011_04_08_presentations/WaterandSpace Heating... · ACM algorithms based on PIER MF central DHW