blank Session VII Right-sized: Equipment and controls for super-efficient building systems September 7 8:30 am to 12:30 pm 4 LU/HSW/SD After designing for maximum passive use of site resources and mitigating energy loads, the next step to a breakthrough building is properly sized equipment and employment of advanced controls. This session will explore the concept and application of designing and specifying equipment and controls for buildings that are already designed to take care of themselves, and need mechanical intervention only during periods of peak demand. Systems such as hybrid natural-mechanical ventilation systems and other approaches to engineer the mechanical system to be as small (efficient) and effective as possible will be explored. Chris Schaffner PE, LEED Nick Gayeski PhD These materials are provided to registered participants in the AIA+2030 Professional Series and may not be reproduced without the written consent of the provider. RIGHT SIZED: EQUIPMENT AND CONTROLS FOR SUPEREFFIICENT BUILDING SYSTEMS™ Logistics and Expectations - Be on time 8:30-8:45 Prior sessions recap and Session 7 intro 8:45-10:30 Case studies/Q&A 10:30-10:45 Break 10:45-11:00 Exercise 11:00-12:30 Case studies/Q&A - Be open, honest and candid - Safe learning environment - Smartphone/Blackberry etiquette -Get to know your new BSA Space- feel at home here! Architecture 2030 Quick overviews-Three related 2030 advocates: - Non-profit organization founded by Ed Mazria in 2002. - Authors of “The 2030 Challenge” - Major Goal: To achieve a dramatic reduction in greenhouse gas (GHG) emissions of the Building Sector by changing the way buildings and developments are planned, designed and The 2030 Challenge AIA 2030 Commitment AIA+2030 Professional Series constructed. Architecture 2030 AIA 2030 Commitment American Institute of Architects requirements The 2030 Challenge How: Two months Six months One year Annually - Design strategies - Technologies/systems - Off-site renewables Source: www.architecture2030.org Establish a team or leader to guide the firm’s plan Implement min. of four actions items related to firm operations Develop sustainability action plan that demonstrates success toward 2030 goals 60% of what? Report progress toward goals and share publicly Source: www.aia.org AIA 2030 Commitment Reporting summary FIRM NAME ALL OFFICES Design Work 2009 Overall Course Goals “The AIA+2030 Professional Series helps design professionals create buildings that meet the ambitious energy efficiency goals of the Architecture 2030 Challenge. Ten 4-hour sessions offer strategies to reach 60% reduction in fossil fuel greenhouse gas emissions, giving design professionals the knowledge and leverage to create next-generation, super efficient buildings-and providing firms with the skills that will set them apart in the marketplace.” LAND USE WATER ENERGY MATERIALS HEALTH AIR QUAILITY Boston Series (Today) 3/16/12 4/13/12 GETTING TO 60: THE POWER OF TARGETS + LOAD REDUCTIONS™ 5/11/12 ACCENTUATE THE POSITIVE: CLIMATE RESPONSIVE DESIGN™ 6/8/12 SKINS: THE IMPORTANCE OF THE THERMAL ENVELOPE™ 7/13/12 PASSIVELY AGGRESSIVE: EMPLOYING PASSIVE SYSTEMS FOR LOAD REDUCTION™ 8/10/12 ILLUMINATING SAVINGS: DAYLIGHTING AND INTEGRATED LIGHTING STRATEGIES™ 9/7/12 RIGHT-SIZED: EQUIPMENT AND CONTROLS FOR SUPER-EFFICIENT BUILDING SYSTEMS™ 10/12/12 SITE POWER: RENEWABLE ENERGY OPPORTUNITIES™ 11/9/12 What is the best solution to this problem? SETTING + ACHIEVING ENERGY GOALS WITH INTEGRATED DESIGN™ THE HAND-OFF + STAYING IN SHAPE: OPERATIONS, MAINTENANCE + EDUCATION™ 12/14/12 PUTTING IT ALL TOGETHER: ACHIEVING 2030 GOALS ON THE PROJECT AND AT THE OFFICE™ A. Reduce the load B. Consider oxen C. Get a bigger donkey lighting LEARNING OBJECTIVES heat loss people solar gain fans & pumps plugs - Describe and apply right-sizing as it pertains to passive energy conservation strategies - Utilize controls to optimizing the efficiency of equipment Before you buy a bigger donkey….. - Incorporate energy efficient strategies to maintain occupant comfort REDUCE LOAD FIRST !! Chris Schaffner, PE, LEED Fellow Principal & Founder The Green Engineer, LLP chris@greenengineer.com Simple Is better than Complex Manual Less Is better than Automatic Is better than More Green means… Passive Is better than Active Energy Efficiency Opportunities • • • • • • • • Building Siting And Orientation Building Massing Building Envelope Plug/Process Loads Lighting HVAC System Domestic Hot Water Elevators • Safe and Healthy • Resource Efficient • Flexible and Adaptable • Durable and Maintainable Strategy For Success 1) Reduce Demand 2) Harvest Site Energy 3) Maximize Efficiency 4) Building Commissioning 5) Ongoing Operations & Maintenance Right Sizing? Potential Benefits of Right Sizing What is Right Sizing? • Match capacity to actual loads. • Match systems to actual operation. • Design for the typical day, not the extreme day (for the 90%, not the 10%) Tunneling Through the Cost Barrier (RMI) Lower capital costs Reduced energy consumption Longer equipment life Improved comfort and indoor environmental quality • smaller, more efficient systems… • …Which lead to less space taken up by those systems… • …Which leads to lower capital costs. • • • • Tunneling Through the Cost Barrier (RMI) Oversizing has a multiplier effect • • • • If I overestimate loads by 25% Then plan for future expansion 25% Then add a 25% safety factor I’ve just oversized my systems by 95% Risks • Unknown/unanticipated conditions (loads, patterns of use) • Unmet design criteria • Value Engineering & Cost Estimating • Liability • Future growth • Fees? Example How many Fume Hoods do we need? How did too many Fume Hoods lead to the need for structural upgrades? Daylighting Example Engineer assumed daylight dimming would be VE’d – never included it in calculations Result - Savings never realized Common Misconceptions Missing Information • “We need to increase system capacity to plan for global warming.” • “Increasingly high tech office systems are driving up internal loads.” • If the engineer doesn’t know, we guess high. • Lighting Design vs. Equipment Sizing • Lack of information needed to properly size systems and fear of liability. “Nobody ever got fired for oversizing a system” Consequences of Oversized Systems • Higher capital costs • Reduced efficiencies and controllability of systems • “cycling” • Start up energy losses • Equipment may not meet rated performance Key Engineering Design Factors • • • • • • Climatic Conditions Architectural Design Design Criteria Internal Loads Diversity Safety Factors Rules of Thumb • Not based on actual loads. • Not based on actual operation. • Already have safety factors built into them. • Often lead to oversized systems. Climatic Conditions • Outdoor Design Criteria –typically defined by codes and standards, client and standard practice. • ASHRAE Design Criteria based on outdoor design conditions 0.4%/99.6% (Most Conservative) 1%/99% 2%/98% (Least Conservative) Climate Data For Boston "'(3,*&+ NK6=MF6 G6 E:IQ=NN:KQ NF6=LH6 L6 FQ=NNQ MM6=LG6 FG6 GQ MI6=LE6 '= Architectural Design Form Orientation Shading Envelope materials Infiltration Rates Complex gets simplified • • • • • • Design Criteria • Comfort Requirements – ASHRAE 55 • “Design for flexibility and growth” • Critical environments - Less tolerant Indoor Environmental Quality (IEQ) • HVAC plays a primary role in IEQ, but not an exclusive one. • Air quality – pollutant source control • ASHRAE 62 – Ventilation • ASHRAE 55 – Thermal Comfort Comfort • ASHRAE Standard 55 provides guidance on thermal comfort Factors • Air temperature • Effect of air movement, or lack of, and velocity. • Radiant effect Adaptive comfort – range of comfort expands when occupants have control. • Mechanical cooling can be eliminated even in warm climates. • Increasing air movement can expand comfort range. Humans and comfort range • Level of activity and style of dress. • Individual controls. • Dress code policies ASHRAE 55 Comfort Zone Internal Loads Diversity • If inaccurate or incomplete load data leads engineers and energy modelers to make best guess assumptions, use of “rules of thumb” and added safety factors. • Where possible, measure • Consider diversity Diversity – Ratio of actual load relative to the peak load, accounts for: • Scheduling - When people are not in the building. • Partial use of equipment, space, etc. • Non-simultaneous loads or use (e.g. not all equipment running at full power at the same time) • Other factors for non-coincidental loads such as usage profiles • Typically ranges from 20-90%! • Engaging the building owner in the diversity assumption discussion and providing both first cost and life cycle cost implications. Real vs. Assumed Equipment Loads Dynamic Load Assessment • Dynamic variations impact system capacity. • Typical cooling assumptions: peak solar gain (sunny day), peak internal gains (constant with no diversity), average daily temperature profile/cycle. • Typical heating assumptions: no solar gain or internal loads benefit, constant temperature. • Dynamic load assessment: real (varying) climate data, real (varying) loads, and realistic operational profiles. • Internal loads: occupant density and associated heat gain (both sensible and latent); occupancy patterns (scheduling); equipment power density (W/sf) and usage patterns; lighting power density (W/sf), controls and usage patterns. • Validation and measurement of available data to identify real loads. • Dynamic load synergy – daylighting Case Study – Harvard Blackstone • LEED Platinum • Office Renovation • Uses demand control ventilation Blackstone - Results • Downsize AHU 15%, resulting in first cost savings • Earned 7 of 10 possible points under EAc1, and also earned IEQc1 • Achieved LEED Platinum • Actual performance within 1% of predicted performance. Reasoning for safety factors in load analysis cool down • Building warm-up and • Future growth/spare capacity • Risk associated with manual system components that rely on occupant participation, such as internal window shades. • Risk due to limited or incomplete internal load information provided by owner and/or design team. • Code considerations Issues in commonly used load analysis programs • Program defaults may assume loads occur 24 hours a day. • Heating or cooling loads not influenced by the value of thermal mass. • Dynamic load profiles or system scheduling are often over-looked. • Most load programs assume airmixing systems with cooling capacity. System Selection Guidelines and Considerations • High system performance at part load. • Adaptability to varying operational (dynamic) loads. • Long-term plan to handle load growth or reduction. • Ease of retrofit appropriate for building type/use, for example: • Simplicity of operation – Avoid designing systems that are not compatible with the available time and expertise of the staff responsible to operate and maintain them. Key mechanical engineering factors • Fan power is reduced by a factor of 3 when system airflow is reduced. • Water is 16 times more efficient at moving energy (btus) than air. • Primary goals for air systems are to reduce system pressure and friction losses, and limit airflow turbulence. Both require effort from the fan to overcome, which in turn creates an energy demand. • • • • • Plant Equipment Recommendations Modular systems Space for future system expansion Multi-stage operation Turndown capability. Variable speed equipment. Mechanical Engineering? 1) Take previous successful set of drawings. 2) Change the box that indicates the name of the project. 3) Submit drawings to client. 4) Building is constructed. 5) Client gripes about discomfort. 6) Wait for client to stop griping. 7) Repeat process. Engineer Eng Lock Lee – “Natural Capitalism” Passive System Evaluation • Are passive and active systems doing double duty – can one be eliminated? • What are the dynamic loads with passive systems in place? • Can active equipment be down-sized due to passive system contribution? • How much of the load does the passive system carry? Can the active backup system be inexpensive and simple if only needed on occasion? • Passive systems do not break or wear out over time – Passive Survivability When does oversizing help? Distribution Systems – Yes • Big pipes = smaller pumps • Marginal cost of a slightly large pipe/ duct/wire is small Plant Equipment – No • Oversized equipment is expensive and runs inefficiently (usually!) HVAC System Alternatives • Compare various HVAC systems Condensing Boilers • Very High Efficiency • Use selection matrix scoring system in decision making. DISPLACEMENT VENTILATION Supply air is introduced at the floor level at a temperature only slightly below the desired room temperature. The cooler supply air "displaces" the warmer room air, creating a zone of fresh cool air at the occupied level. Heat and contaminants produced by activities in the space rise to the ceiling level where they are exhausted from the space TM570 Environmental Systems I: HVAC DEDICATED OUTDOOR AIR SYSTEMS (DOAS) HYDRONIC SYSTEMS CAN BE COMBINED WITH A VENTILATION ONLY, AIR SYSTEM, TO PROVIDE WHAT IS CALLED A DEDICATED OUTDOOR AIR SYSTEM OR DOAS. DOAS SYSTEMS INSURE THAT ADEQUATE VENTILATION IS PROVIDED REGARDLESS OF HEATING OR COOLING REQUIREMENTS. DUCTS ARE SIZED JUST LARGE ENOUGH FOR VENTILATION – TYPICALLY 1/5 THE SIZE THAT WOULD BE REQUIRED FOR FULL CONDITIONING IN AN AIR BASED SYSTEM. THIS SYSTEM TYPE HAS ADVANTAGES IN TERMS OF INDOOR AIR QUALITY AND ENERGY EFFICIENCY. IN THE RECENT PAST MOST BUILDINGS HAVE BEEN DESIGNED WITH VAV SYSTEMS, BUT THERE IS CONSIDERABLE INTEREST IN DOAS IN THE BUILDING COMMUNITY. TM570 Environmental Systems I: HVAC UNDERFLOOR DISPLACEMENT THE DISPLACEMENT CONCEPT IS COMBINED WITH A RAISED ACCESS FLOOR. IN ADDITION TO THE BENEFITS FROM THE DISPLACEMENT CONCEPT, IT ALSO PROVIDES ADDED FLEXIBILITY, IN THAT SPACES CAN BE EASILY RECONFIGURED. TM570 Raised Floor being installed Environmental Systems I: HVAC DOAS • Fan Coils • Chilled Beams • Radiant Variable Refrigerant Volume Heat Pumps • Distribute refrigerant instead of water. • Multiple heat pumps on single condensing unit • Inherent heat recovery HVAC Controls • On/off • Demand response controls • Metering/monitoring Architect’s Role in Right Sizing • • • • • • Early dialogue with engineering team Set energy targets Set specific system level targets Require energy analysis Owner communication and education Empower the engineering team to right size their systems *%4,'$ (! '+-,0,(* ', *-1'*+*! !'$+,(9%,*'*488"*,(*84+,&+' "'*"' *(0)8)*,&',("%"-+8 ++!0+/+ '+-,0,(!'(%( 4 *(#,9(! '+-,0,(* ', *-1'*+*! *(#,9(! '+-,0,(* ', *-1'*+*! (-('9 *9 *( *&9 (&)%-('9 &*" 8 HJL8EEE + "(%( 4="(' "'*"' GEFE % 0))(*, HQ = &"'"+,*-(' GFQ 0))(*, GFQ + ' ',*-(' + (* GJQ HEQ *( *&"+,*"0-(' (0,!%1-(' Building Shell Piping Systems " !*(*&''1%() "'+*' %"' (0,! 0'+!+ " ! *(*&' %5"' + + + (! '+-,0,>4)"%%((* F0&((= JIE AF:J0&((= JIE3B Ductwork Systems '* 4('+*1-(',0*+ Two Themes ,(1*4 ,") (2%(",4 0,2(*$ Predicted Peak Energy Loads FJ;>E<%((*>,(>((* ('9 • +"' '-%-(' • !"%%&+ Design Phase Predictions Predicted Peak Energy Loads • By Engineer • Equipment sizing • By MIT • Utility planning Predicted Annual Energy Consumption (kBTU/sf/yr) • • • • By energy model Evaluate design alternatives Determine utility incentives Document LEED Credits Predicted Annual Energy Consumption (kBTU/sf/yr) Energy Modeling as a Design Tool Early modeling Evaluate design alternatives • Building envelope • Shading • HVAC System Selection Mid-design modeling Refine strategies Final Documentation Model For LEED Balance Point Temperature Calculation MIT Data Collection Strategy ,& • ,*2",!FJ9F,0*'(2'>(' &,* !"%%2,* • ,*2",!>('&,* %,*"",4 • "'A(0%'+2",! *B&,* • **$*+&,* • %,*('",*")=&,*"' *$*+ • (2*( ")(2*&,*+ -%",4 *&,*+ Metering Issues Multiple trades involved – Electrical – Data – Pipe fitters – Controls Demand – Chilled Water Results to Date Chilled Water • Design demand: 3,350 tons Most engineers do not understand Diagrams needed for inclusion in drawing set • MIT prediction: 2,484 tons • Actual demand: 2,354 tons Ranges on meters – Engineers’ numbers not reliable – Over sizing: loses low end accuracy Demand – Steam Results to Date ,&? @ +" '&'9 HJ8EEE))! @ )*"-('9 Demand - Predicted Electrical Load Details Electrical Design: • Lighting: 335 kVA (1.04 W/sf) GJ8NGE))! @ ,0%&'9 GE8IHJ))! • Receptacle: 2,344 kVA • Mechanical: 2,326 kVA (6.6 W/sf) (6.6 W/sf) Demand - Results to Date Demand Estimation %,*"%&' Why do we overestimate the load? @ +" '9 @ I8IJI$ AFI:K=+B @ )*"-('9 @ H8GIE$ AN=+B @ ,0%9 @ F8HKE$ AH:MF=+B • Engineers are conservative !!!! – Multiple safety factors – Process loads are overestimated – Rules of Thumb outdated – Lack of feedback Usage Results to Date Causes of Disparity Predicted vs. Actual (Site) Energy Use: Why models differ from reality: Labs21 Average: 393 kbtu/sf/yr Predicted: 365 kbtu/sf/yr Actual: 323 kbtu/sf/yr • 12% less than predicted • 19% less than Labs21 average • Same issue with assumptions as peak loads • More assumptions in play –schedules, part loads • Assumes systems operate perfectly • Some modeling elements forced by 90.1 • Weather • 38% less than ASHRAE 90.1-2004 KGS: Who We Are & What We Do Right Sizing HVAC Equipment: Controls, Operations and Performance Nick Gayeski, PhD Partner and Co-Founder Engineers, scientists and software developers Clockworks: Web-based software & analytics library for automated fault detection and diagnosis, ongoing commissioning, measurement and verification Engineering services to support our customers Copyright © 2012 Copyright © 2012 Topics KGS: Bearing witness to right and wrong sizing Trending equipment performance data 24/7/52 Right sizing conventional wisdom Automated analytics detect when systems are not performing properly Right sizing controls How does right/wrong sizing impact operational performance? Direct and assist owners, O&M, and service providers to take action to correct problems, including the outcomes of wrong sizing How do I avoid this mess and deliver high performance buildings? Copyright © 2012 Copyright © 2012 Right sizing conventional wisdom – a review Right-sizing controls Reduces capital costs Operational strategies and controls can be made to use the right systems, at the right times, just enough • Smaller boilers, chillers, pumps, pipes, coils, ducts, etc • Less space for equipment? Reduces operational costs Systems designed with flexibility to adapt to real conditions rather than over-sized to handle extremes • More efficient operation = less energy use + lower energy costs • • • • Reduces maintenance costs • Less cycling/appropriate use = longer life, less wear Variable speed drives Equipment that is efficient at part-loads Proper zoning and scheduling Controls that adjust to real thermal loads and drivers Happier occupants, happier clients • More comfortable conditions, better indoor env. quality • Higher performance buildings Copyright © 2012 Copyright © 2012 Right-sizing controls On/off and turning it down in practice • Time-of-day scheduling • • If you don’t need it, turn it off If you don’t need it so much, turn it down • • Copyright © 2012 Instructions to junior staff from a senior operator turned researcher at a national laboratory on how to operate buildings efficiently On/off of equipment or availability Static pressure • Night setbacks/setups • Reset schedules • • • • • Variable speed drives to allow modulation to loads • • • Posted on the door outside the operations center for a 50+ building national facility with >$1 billion business volume Copyright © 2012 Static pressure reset based on damper positions Differential pressure reset based on coil valve positions Discharge air temperature reset Outdoor air temperature reset schedules Pumps Fans Chillers/compressors* It’s simple, but details still matter Take chiller efficiency, for example • Some chillers operate efficiently at full-load • Some chillers operate efficiently at part-load • Especially in retrofit projects • • • • Find out how reducing thermal loads changes the operating conditions of the HVAC equipment Can the system modulate to accommodate changes in the thermal loads? How does that effect its efficiency? Consider additional HVAC retrofits? E.g. VSDs Architects need to • • • Copyright © 2012 Ask engineers to explain how design decisions effect system performance and sizing, but also PROVIDE INFORMATION to help engineers answer those questions Enable performance management • Ensure the building automation system includes adequate data to measure performance • Provide for long term monitoring and trending of performance data • Leverage new technologies to provide Optimal and model-predictive controls Emerging technologies for model-predictive control and optimization may • • Reduce peak loads • Reduce demand charges • Reduce overall energy costs For example • • Building IQ • Clean Urban Energy • Optimum Energy Does it work? Can we model and design with it? • • To be determined Copyright © 2012 e.g. Automated diagnostics identify wrong-sizing performance impacts and corrective actions • Automated ongoing commissioning • Fault detection and diagnosis • Ongoing performance measurement and verification • Information enables adaptation to wrong-sizing et al • As-built performance always differs from expected • Use, operations, and performance changes with time Copyright © 2012 Copyright © 2012 Case study: Over-sized rooftop units Summary • • • • • Small retail store 5 rooftop units Diagnostics for commissioning Compressor cycling on 1 RTU RTU capacity over-sized Case study: Over-sized VAV systems • Higher static pressures lead to more fan energy • Low VAV box damper positions imply that zones require lower airflows to meet cooling than design • Reducing static pressure causes fan to slow down and consume less energy, deliver less flow, and allow dampers to open Consequences • Shorter compressor life Solution • • • • Copyright © 2012 Programmable thermostats Time of year schedules Only use RTU in extreme summer Right-size/replace RTU Copyright © 2012 Case study: Over-sized VAV systems Summary • • • • • Large research laboratory 100,000 CFM AHUs Serving 50-100 VAV boxes Low average damper positions High static pressure setpoint Case study: Oversized boiler/heating system Summary • • Multi-family residential building Boilers short cycling Consequences • • More maintenance required Shorter boiler life Consequences • Wasted fan energy Solutions • Solutions • • Dynamic static pressure reset Reduce static pressure setpoint Copyright © 2012 • Chillers are generally more efficient delivering higher chilled water temperatures Case study: Oversized cooling system Summary • • • • • Keep boilers off more of the year Reduce heating hot water supply temperature Right-size the boilers Copyright © 2012 Case study: Oversized cooling systems • • Small temperature differences on a chilled water loop means the loop thermal load is small relative to the capacity Supply temperature raised to improve chiller efficiency or flow reduced to reduce fan power and save energy costs • Large commercial building CHW Loop exhibited low temperature differences Nighttime operation unnecessary except for small data center Consequences • • Excess chiller operation Additional energy costs Solutions • • Copyright © 2012 Copyright © 2012 How and why does wrong sizing happen? How do I avoid this mess and deliver high performance buildings? Risk and liability Establish customer expectations and goals early • Design for extreme conditions (0.4% design day) • Safety factors on safety factors • Customer expectations on comfort and adaptability Coordinate design process effectively and ensure accurate information is provided for sizing Bad assumptions and lack of information • • • • Copyright © 2012 Proper zoning of systems Dedicated sensible cooling for data center Understand the importance of Occupancy levels, schedules and patterns Lighting power density and patterns Plug load power density and patterns Limitations of modeling tools/modelers • matching loads to capacities efficiently, • operation and efficiency of systems at part-loads, and • controls that modulate systems to efficiently meet loads Construction 101 Utilize new technologies to • Design vs as-built • Design vs as-operated • assure performance goals are met, • address as-built system problems and inefficiencies, and • deliver energy efficiency and peak load reduction Copyright © 2012 Thanks! Questions! Nick Gayeski, PhD Partner and Co-Founder Image Credits: Pacific Northwest National Laboratory, ReTuning Resources BuildingIQ KGS Buildings, LLC Copyright © 2012