Future HVAC Efficiency Improvements 08-05-2013

Richard Lord

Background • Since the 1970’s efficiency requirements for HVAC systems have increased

using a method of prescriptive minimum requirements defined thru standards like ASHRAE 90.1, IECC and federal requirements.

• Some are controlled and enforced at a national level, and others are implemented at state and city levels.

• The approach has been to define minimum efficiencies that are based on industry standard full load rating metrics like EER, COP, kw/ton, etc.

• Recently, for a few of the products, new metrics focused on average annualized performance have been added which include metrics like SEER, HSPF, IPLV, and IEER

• All these have been based on one requirement for the USA and with the assumption of equipment sized for the exact building load (no over sizing)

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Background • Great progress has been made in mechanical system efficiency improvements

which in most cases have exceeded the overall improvement to ASHRAE 90.1

3 Chart based on ASHRAE 90.1 determination study conducted by PNNL

Possible Future Roadmap

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Commercial HVAC Efficiency Requirements

ASHRAE 90.1 Building Target

Possible Path to nearly Net Zero Buildings

Equipment Level Limit

MaxTech Limit Full Load Efficiency

Systems Approach &Renewable Energy

Chart is an estimate of possible future regulations to achieve Near Net Zero by 2034 based on studies done by Carrier on technical limits of HVAC equipment

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Future Efficiency Improvements • As we approach the technical limits, the cost to increase efficiency increases

exponentially and we are finding that some changes can not be cost justified as shown by the recent ASHRAE 90.1 chiller efficiency justification

• Overall the capacity weighted payback period was 6.3 years but there is a wide variation by product type and climate zone ranging from -320 years to +37.6 years

• Overall these products are approaching the Technological limit (“Max Tech”) and other improvements will have to be explored

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Scalar limit is the maximum allowable payback period allowed by ASHRAE 90.1 economic procedures. We know customers really are only willing to accept 3-4 yrs

Chart from ASHRAE 90.1 Addendum CH to the 2010 Standard Justification Analysis

ASHRAE 90.1 Product ClassMin Avg Max Scalar Limit

AC<150 Tons 1.1 4.7 10.9 9.086AC>150 Tons 0.9 4.2 9.2 9.086WC Positive <75 Tons 1.1 5.2 17.5 11.962WC Positive >75 &<150 Tons 1.6 5.9 17.9 11.962WC Positive >150 &<300 Tons 1.3 6.1 17.0 11.962WC Positive >300 &<400 Tons 2.0 9.8 26.2 11.962WC Positive >400 &<500 Tons 1.5 5.3 12.5 11.962WC Positive >500 &<600 Tons 1.5 5.3 12.5 11.962WC Positive >600 Tons 1.0 4.7 15.4 11.962WC Centrifugal <75 Tons -320.5 -54.0 37.6 13.626WC Centrifugal >75 &<150 Tons -155.3 -24.8 26.2 13.626WC Centrifugal >150 &<300 Tons 1.0 5.2 15.8 13.626WC Centrifugal >300 &<400 Tons 2.7 10.9 39.0 13.626WC Centrifugal >400 &<500 Tons 1.5 10.3 46.3 13.626WC Centrifugal >500 &<600 Tons 1.3 12.3 39.0 13.626WC Centrifugal >600 Tons 1.2 7.0 28.5 13.626USA Weigthed Average 6.3

Justified Not Justified

Payback Years

Future Efficiency Improvement Options

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Historical Approach (Business as usual) - Full Load Improvements

• We are approaching “Max-Tech” on many products and significant improvements in base product full load efficiencies will be limited and often not cost effective

• We also face issues with the phase down of the HFC refrigerants that are used today, and will have to evolve to new lower GWP refrigerants that may not be as efficient, could be semi-flammable and could be more expensive to apply

Alternate Approaches to Consider 1. Switch to new part load or annualized metrics like IPLV for chillers and IEER

for rooftops, splits, and VRF 2. Hybrid system with rating approaches like AHRI guideline V 3. Subsystems approaches (focus of discussion today) 4. Whole Building System approaches (ASHRAE Building Energy Quotient) 5. Defined commissioning requirements to make sure equipment runs correctly 6. Integrated Fault Detection (FDD)

Subsystem Approaches • Today, the focus of AHRI Standards and Federal regulations are at the

equipment and component level At standard ratings conditions, and typically at full load. Efficiency is defined at a component level, but for complete systems many of

the components like pumps, towers, terminals and multiple units are not considered

Performance does not factor in actual building loads Do not factor in annualized operation in most cases Performance does not factor in local weather conditions and requirements Many times the operation is at non-rating operating conditions (i.e.. fan

static, chilled water temperature, air and water flow, economizer use, energy recovery use, etc) which is also not considered

Over sizing of equipment is not considered Multiple units are not considered

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Current practice is not to consider the complete system, as applied in the actual building including local weather data and as a result the energy and cost of the system may not be the optimal solution and tend to limit creativity

Chiller Water “System” Example

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Cooling Tower

Condenser

Evaporator

Condenser Water Pump

Compressor

Air Handler

Chilled Water Pump

Conditioned Space

Current 550/590 Chiller Standard and Certification focus ASHRAE 90.1 Full and part load efficiency

ASHRAE 90.1 fan power requirement, no approach requirement and ignore water use

No focus on condenser water pumping power other than a pipe sizing requirement

No focus on chilled water pumping power other than pipe sizing

No focus on duct pressure drop and very little on applied fan power

Very little focus on the effective air distribution

Do not address multiple chillers and towers although most are applied that way

No integration of economizers, exhaust fans, ERV and IAQ

Outside Air

Regulations No regulations

Chart prepared by Richard Lord

Packaged Ducted Rooftop “System” Example

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Packaged Rooftop

Conditioned Space

Rating of the rooftop EER and IEER with part of the fan power is covered by AHRI 340/360 but we do not certify the full operating map

Only part of the duct work pressure drop included in the ratings

No annualized performance for heating

Demand ventilation not reflected in ratings

ERV/Rooftop CEF can be used for full load, but not part load and annualized

Power Exhaust not included in ratings

Very little focus on the effective air distribution

On VAV units reheat not reflected in ratings

Economizer and outside air not reflected in ratings

Chart prepared by Richard Lord

Future Roadmap

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Our Historical approach of using prescriptive requirements for components has been used since the 1970’s and is reaching the technological limits and alternate approaches need to be considered

Future Energy Reduction Strategies

Historical approach using prescriptive

component requirements

Subsystems and Systems Approach

Status Quo - We feel this will have limited success

and will be costly

Change required - will require different tools, revision to standards

and to federal laws

?

Chart prepared by Richard Lord

Industry Initiatives • The alternate approach to future HVAC efficiency requirements has been

discussed in many presentations and meetings and the industry has started to form groups and committees to work on proposals. ASHRAE 90.1/189.1 AES (Advanced Energy Standards) – This group

has existing for several years and is including in their work tasks systems and subsystems concepts as well as many other changes to improve the standards

AHRI SWG (Systems Working Group) – This group was formed earlier this year and is composed of a cross section of very experienced HVAC design people. The are work on many improvements to AHRI with a focus to move to an HVAC systems approach to energy efficiency for the future

ASHRAE 90.1 Mechanical Subcommittee Systems Working Groups – Two committees have been formed to develop a third compliance path for HVAC Systems with one focused on chilled water systems and the other focused on rooftop systems

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ASHRAE 90.1 HVAC Systems Concept • A tool of some type will be required to determine the system level efficiency,

but the ASHRAE 90.1 effort will not focus on the tool and the AHRI SWG will lead this effort.

• Complete unit rating maps will be required to do system analysis and this will require changes to ratings standards and certification programs which the AHRI SWG will lead the effort on, but new standard like ASHRAE 205 are being developed

• The initial focus of the ASHRAE 90.1 effort will be on two systems Chilled Water Plant System

Packaged Rooftop System

• It is likely that the requirements will be function of the building type as well as

climate and some normalized system performance factor may be required

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Chilled Water System Example (Current)

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Current ASHRAE 90.1 Regulations (Prescriptive Approach)

Full Load & IPLV HP/GPM

Full Load & IPLV HP/GPM

Maximum Fan Power

CO2

Component Efficiency Requirements

No Requirements

Prescriptive Requirements

Chart prepared by Richard Lord

Chilled Water System Example (Proposed)

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Proposed Systems Approach

Maximum Fan Power

CO2

Annualized HVAC System Efficiency (annualized)

Overall Efficiency Minimum Set by climate zone and building type and then component efficiencies can be traded off to meet the overall targets

System Level Climate Zone Efficiency

Requirements

Chart prepared by Richard Lord

HVAC Systems Concept • The HVAC systems concept would involve the following;

User would select from one of the 15 ASHRAE 90.1 Benchmark buildings closest to the proposed building (may need more building types).

ASHRAE 90.1 committee would define the baseline system using industry reasonable best practices and this then would be the baseline HVAC System efficiency. This would include HVAC efficiencies as well as all components in the system (i.e.. Cooling towers, pumps, economizer, etc.)

User would then run proposed system using the system computer tool (hourly) using the selected benchmark building, and weather data from one of ASHRAE 90.1 17 climate zones benchmark cities.

If the proposed HVAC system uses less power then the benchmark system then the system could be used.

Key to the approach is that all annualized power of the complete system is considered

User would be allowed to trade off all aspects of the system as long as the annualized energy use was equal to or less. (i.e.. Chiller efficiency, cooling tower approach, pumping power, economizers, energy recovery, fan power, etc)

Goal is to start off with equal performance to the prescriptive approach 15

Example Common Best Practice System

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Chiller Type

No Chillers

Chiller LWT

Chiller GPM/Ton

Chiller Flow Chiller Pump Power

Tower Approach

Tower Fan

Power

Tower Flow

Tower Pump Power

Indoor full load

CFM/ton

Terminals Economizer Energy Recovery

1A Miami AC 2 44 2.4 Variable Primary 22 6.47 40.2 constant 19 350 VAV no yes1B Riyadh AC 2 44 2.4 Variable Primary 22 6.4 40.2 constant 19 350 VAV no no2A Houston AC 2 44 2.4 Variable Primary 22 9.23 40.2 constant 19 350 VAV Air no2B Phoenix WC 2 44 2.4 Variable Primary 22 9.02 40.2 constant 19 350 VAV Air yes3A Memphis AC 2 44 2.4 Variable Primary 22 7.46 40.2 constant 19 350 VAV Air yes3B El Paso WC 2 44 2.4 Variable Primary 22 8.85 40.2 constant 19 350 VAV Air no3C San Francisco AC 2 44 2.4 Variable Primary 22 6.47 40.2 constant 19 350 VAV Air no4A Baltimore AC 2 44 2.4 Variable Primary 22 10.02 40.2 constant 19 350 VAV Air yes4B Albuquerque WC 2 44 2.4 Variable Primary 22 6.98 40.2 constant 19 350 VAV Air no4C Salem AC 2 44 2.4 Variable Primary 22 7.02 40.2 constant 19 350 VAV Air no5A Chicago AC 2 44 2.4 Variable Primary 22 9.83 40.2 constant 19 350 VAV Air yes5B Boise AC 2 44 2.4 Variable Primary 22 7.91 40.2 constant 19 350 VAV Air no5C Vancouver AC 2 44 2.4 Variable Primary 22 10.05 40.2 constant 19 350 VAV Air no6A Burlington AC 2 44 2.4 Variable Primary 22 9.81 40.2 constant 19 350 VAV Air yes6B Helena AC 2 44 2.4 Variable Primary 22 11.15 40.2 constant 19 350 VAV Air yes7 Duluth AC 2 44 2.4 Variable Primary 22 8.27 40.2 constant 19 350 VAV Air yes8 Fairbanks AC 2 44 2.4 Variable Primary 22 10.6 40.2 constant 19 350 VAV Air yes

400 Ton (example)Climate Zone City

Concept is to define by climate zone, building type, and capacity size the reasonable best practice for systems which becomes the base line. Then for your proposed system you pick one of the baseline building and city for your climate zone. You can then trade off design attributes (i.e.. Chiller type, economizer, pumping power, terminal type, etc) and as long as your annualized efficiency is better then your system is acceptable. Analysis requires a tool that is an hourly analysis, but uses default buildings and a default complete system as the base

Chart prepared by Richard Lord

Example System Level Metrics

• The following example shows what the targets might look like for a typical large office building.

• We will likely use some efficiency metric like watts/ft2 or kw/ton

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Larger Office Building Cooling Example

400 Ton Office Building with Dual Air Cooled Chillers (Cooling EER, no heating)

COOLING MECHANICALhrs hrs - Tons Mw-hrs Btu/watt1 2 3 4

1A Miami 5878 5878 no 872461.7 1287.0 8.131B Riyadh 6859 6859 no 762687.6 1503.8 6.092A Houston 5336 4262 yes 684886.9 954.0 8.612B Phoenix 5887 4593 yes 492643.4 856.8 6.903A Memphis 5147 3420 yes 531100.1 724.3 8.803B El Paso 5404 3538 yes 652380.0 909.7 8.613C San Francisco 5014 1853 yes 342041.5 284.6 14.424A Baltimore 4785 2464 yes 386684.1 482.4 9.624B Albuquerque 5138 2502 yes 482625.2 660.8 8.764C Salem 4659 1675 yes 319272.2 323.9 11.835A Chicago 4586 1918 yes 341031.3 399.1 10.255B Boise 4821 1862 yes 403843.9 486.0 9.975C Vancouver 4614 1203 yes 319515.7 228.0 16.826A Burlington 4420 1683 yes 294689.9 306.0 11.566B Helena 4801 1373 yes 442209.4 479.9 11.067 Duluth 4443 1122 yes 268881.6 221.2 14.598 Fairbanks 4016 803 yes 232382.0 144.3 19.33

Zone CITY

OPERATING HRS HVAC SYSTEM POWER

ECONOMIZER ANNUAL BUIDLING

LOAD

HVAC SYSTEM ANNUAL EER

Base 200 Ton AC Chiller has an 11.1 EER and 14.0 IPLV

Chart prepared by Richard Lord for the ASHRAE 90.1 Chilled Water Plant Analysis

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Annual Cooling EER (400 Ton Office Building)

Miami 1A (8.13)

Houston 2A (8.61)

Phoenix 2B (6.90)

Memphis 3A (8.80)

El Paso 3B (8.61)

San Francisco 3C (14.42)

Baltimore 4A (9.62)

Albuquerque 4B (8.76)

Salem 4C (11.83)

Chicago 5A (10.25)

Boise 5B (9.97)

Burlington 6A (11.56)

Helena 6B (11.06)

Duluth 7A (14.59)

Fairbanks 8 (19.33)

Example – Does not including heating operation

For ASHRAE 90.1 Climate zones and benchmark cities standard work

Benchmark Buildings • The following is the current list of buildings

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Building Type Name Floor Area ft2 Number of FloorsLarge Office 498,600 12Medium Office 53,600 3Small Office 5,000 1Non-refrigerated warehouse 50,000 1Stand-alone Retail 24,695 1Strip Mall 22,500 1Primary school 739,600 1Secondary school 21,900 2Fast Food 2,500 1Restaurant 5,502 1Hospital 241,400 5Outpatient health care 10,000 2Small hotel/motel 43,000 4Large hotel 100,000 6Mid-rise apartment 33,600 4High-rise apartment 84,000 10Movie theater/Cinema TBD 1

We may have to add some types and make modifications to the above. Intent is to normalize to a building area or other attribute so they can be scaled to the intend building size

Buildings are based on the ASHRAE 90.1 PNNL Determination models

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Overall Assumptions for this Study • Building Models

ASHRAE 90.1 and PNNL have developed benchmark buildings that are used for evaluations and the determination..

Large Office 498,600 ft2 12 floors

Hospital 241,000ft2 5 floors

Buildings are based on the ASHRAE 90.1 PNNL Determination models

Proposed Concept – Building Load Profiles • Analysis would be done on an hourly basis using the loads from the

benchmark building closest to the intended application in the climate zone benchmark city

21 Based on the ASHRAE 90.1 PNNL Determination model for a large office

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Climate Zones/Benchmark Cities (Current)

All the climate zones are mapped to international countries and cities in ASHRAE 169 and ASHREAE 90.1

ASHRAE 90.1-2010 Climate Zones

Miami 1A Houston 2A

Phoenix 2B

Memphis 3A El Paso 3B

San Francisco 3C

Baltimore 4A

Albuquereque 4B

Salem 4C

Chicago 5A

Boise 5B

Burlington 6A

Helena 6B

Duluth 7A Fairbanks 8

Future Climate Zones (ASHRAE 169)

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Climate zones will increase from 17 to 20 and some of the benchmark cities will change

ASHRAE 169 Second Public Review Proposed new climate zones

Implementation Concept • Currently ASHRAE 90.1 has a mandatory and prescriptive section for

mechanical HVAC systems • This concept would add a third compliance option which would be an HVAC

systems analysis • We could use it as an option or could make it mandatory for some larger

systems (i.e.. Large office buildings greater than 25,000 ft2) • For higher tier standards like ASHRAE 189.1, FEMP and utility rebates the

same approach could be used, but with a higher efficiency system energy metric target

• For future standards we could either update the best practices for the baseline system or just do analysis to raise the efficiency metric for the HVAC systems

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Concept is not totally defined, but the key takeaway is that we would focus efficiency metrics at the HVAC system level and not focus on components like the chillers, cooling towers, fan motors, compressors which is the current regulatory approach

Additional Thoughts and Options • Once we have a systems metrics, there may be other attributes and credits that

we can add to encourage best practices. • These might be implemented by a decrease in the energy metric

Credit for concepts like demand ventilation above the minimum Credit for ventilation effectiveness Credit for renewable energy Credit for energy recovery Credits for addition of sub-meter metering Credit for energy monitoring and dashboard reports Credits for adding controls diagnostics Credit for connection to the Smart Grid and demand limiting Credits for commissioning and re-commissioning best practices Credit for thermal and energy storage

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All the above can save significant energy but under current regulator rules they are not considered in the energy savings and therefore the incentive to use these concepts is not supported

Short Term Action Plan • The short term plan for each system is to define what is included in the

system. For this we will use versions of the system diagrams and decide where the thermodynamic control box will be draw around the system

• We should also consider what components and options should be included in the system. For example should the chiller system include heat recovery, thermal

storage, etc. Should the rooftop include economizer, energy recovery, evaporative

cooling. Should each of the system include the terminals and room air distribution

and concepts for space control, like demand ventilation.

• The short term plan lead by the ASHRAE 90.1 committee will define what are considered good practices for the components like pumps, fans, etc and the overall systems.

• AHRI SWG needs to begin on the development of the tool and supporting infrastructure

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Discussion

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Possible Discussion Topics • What does the group think of the overall concept and are there suggestions and

comments that the working groups should consider?

• This will be a radical change to current approaches defined by federal law and current standards. How do we get the change started?

• This will present new problems to enforcement by AHJ and local code officials. What can be done to get this change in place?

• What are you thoughts on credits being used to allow for post occupancy energy savings ideas like diagnostics, re-commissioning, meters, etc?

• Are there other groups that we need to talk to and include in the development of the concept?

• If we proceed with this, how can we get funding support for the development of tools?

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