Planning, Design and Operation of Net Zero Energy Buildings · 2 ASHRAE RP 1651 Development of Maximum Technically Achievable Energy Targets for Ultra-Low Energy Use Commercial Buildings

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Planning, Design and Operation of Net Zero Energy Buildings

Charles Bertuch

Bergmann Associates


Learning Objectives

• Understand different classifications of Net Zero Energy buildings• Lean key criteria of planning a NZE building• Review design considerations relative to NZE buildings• Review lessons learned from a NZE project• Review the planning and design of a “gound-up” NZE design


Overview

• What is Net Zero Energy

• Regulatory Drivers

• Planning

• Design Considerations

• Case Studies


Definitions

Zero Energy Building• US DOE: An Energy Efficient Buildings where, on a source energy basis, the actual

delivered energy is less than or equal to the on-site renewable source energy exported

• Source Energy: Accounts for energy losses in thermal combustion power plants and transmission/distribution losses to the building site

• Source Energy Conversion Factors (r) (ASHRAE 105)Electricity (Import and Export) 3.15Natural Gas 1.09Steam 1.45Hot Water 1.35Chilled Water 1.04

• Site Energy vs. Source Energy


Esource = Si (Edel,i rdel,i) – Si (Eexp,i rexp,i)

All Electric

• 300,000 kBTU elect delivered

• 320,000 kBTU exported from PV

Esource = (300,000 kBTU x 3.15) – (320,000 kBTU x 3.15)

= -63,000 kBTU



Electric & Natural Gas


• 60,000 kBTU NG delivered


Esource = (200,000 kBTU x 3.15) + (60,000 kBTU x 1.09) – (260,000 kBTU x 3.15)

= -123,000 kBTU



Electric & Natural Gas with CHP


• 260,000 kBTU NG delivered


Esource = (120,000 kBTU x 3.15) + (260,000 kBTU x 1.09) –(210,000 kBTU x 3.15)

= -100 kBTU

Note: On a site energy basis – would not meet NZE


Types of NZE Buildings

• Class A All renewable energy generated within Building Footprint

• Class B All renewable energy generated within Site Boundary

• Class C Off-site renewable fuels (wood pellets, biodiesel, etc.) used to generate on energy on-site

• Class D Purchase of renewable energy generated which is generated off site

Some consideration is being given to Time Dependent Value Energy (TDV) where a KWH produced during high cost peak hours is valued more highly than a KWH produced during off peak hours


Drivers

• California Title 24 – Goal of NZE houses by 2020, commercial buildings by 2030

• California Executive Order B-18-72 – 50% of existing state-owned buildings by 2025, NZE for all new/remodeled buildings by 2025

• US Executive Order 13514 – 100% of new federal buildings NZE by 2030

• AIA 2030 – Pledge that all buildings designed NZE by 2030

• Retrofit NY – Incentives to implement “near-NZE” buildings for multi-family renovations


Learning Assessment

• Name the (4) different classifications of Net Zero Energy buildings


Learning Assessment

• Name the (4) different classifications of Net Zero Energy buildings

• Class A All renewable energy generated within Building Footprint

• Class B All renewable energy generated within Site Boundary

• Class C Off-site renewable fuels (wood pellets, biodiesel, etc.) used to generated on energy on-site

• Class D Purchase of renewable energy generated which is generated off-site


Planning a NZE Building Demand Side

2013 ASHRAE 90.1

(kBTU/SF/Yr) 12016 ASHRAE 90.1

(kBTU/SF/Yr) 1

Max Tech Feasible Site

EUI Reduction

(vs. 2013) (kBTU/SF/Yr) 2

Minimum Tech Feasible

Site EUI

(kBTU/SF/Yr)

Offices (Med) 33.4 31.8 64% 12.0

Retail (Stand Alone) 45.7 41.8 64% 16.4

Education (Secondary) 42.1 36.6 64% 15.2

Hospital 122 120.1 42% 70.5

Hotel (Large) 89.4 85.2 37% 56.2

Warehouse 17.6 14.8 64% 6.4

Restaurant (Full Service) 371.3 366.1 31% 257.3

Apartment (Mid-Rise) 43.5 41.9 35% 28.5

Total Building Energy Use < On-Site Renewable GenerationUse - Energy Utilization Index (EUI) kBTU/SF/Yr

1 US DOE – Preliminary Energy Savings Analysis of ANSI/ASHRAE Std 90.1-2016 (2017)2 ASHRAE RP 1651 Development of Maximum Technically Achievable Energy Targets for Ultra-Low Energy Use Commercial Buildings (2016)


Maximum Rooftop PV CapacitySupply Side

a – Solar altitude at noon on winter solsticeb – PV panel tilt

h = 𝐿 × sin(𝛽)𝑆𝑒𝑝𝑎𝑟𝑎𝑡𝑖𝑜𝑛 = ℎ ÷ tan(α)

𝑃𝑟𝑜𝑗𝑒𝑐𝑡𝑖𝑜𝑛 = 𝐿 × cos(𝛽)


Maximum Rooftop PV Capacity

a = 23.5o

Tilt KWH/KW Sep Proj

0 1109 0.00 1.00

5 1150 0.20 1.00

10 1183 0.40 0.98

15 1212 0.60 0.97

20 1231 0.79 0.94

25 1245 0.97 0.91

30 1252 1.15 0.87

35 1251 1.32 0.82

40 1242 1.48 0.77

45 1228 1.63 0.71

50 1208 1.76 0.64

55 1179 1.88 0.57

60 1144 1.99 0.50


Maximum Rooftop PV Capacity

Tilt Sep Proj Sep + Proj KHW/KW 1

0 0.00 1.00 1.00 1109

5 0.20 1.00 1.20 961

10 0.40 0.98 1.38 855

15 0.60 0.97 1.56 776

20 0.79 0.94 1.73 713

25 0.97 0.91 1.88 663

30 1.15 0.87 2.02 621

35 1.32 0.82 2.14 585

40 1.48 0.77 2.24 553

45 1.63 0.71 2.33 526

50 1.76 0.64 2.40 502

55 1.88 0.57 2.46 480

60 1.99 0.50 2.49 459

1 Effective KWH/KW for Given Roof Area

Plan ViewHorizontal

Plan ViewSloped


Collector to Floor Ratio (CFA)SF of Required PV ÷ SF Building

1 Story 2 Story 3 Story

Rooftop PV: CFA = 0.33

Charles Eley, FAIA, PE


Required Collector to Floor Ratio

• Solar Production 1109 KWH/KW/Yr (horizontal)

• SF PV/KW 65 SF PV/KW

• Solar Production 17.1 KWH/SF PV/Yr

• Solar Production 58.3 KBTU/SF/Yr



Required Collector to Floor Ratio

2013

ASHRAE 90.1

(kBTU/SF/Yr) Required CFA

2016

ASHRAE 90.1


Max Tech

Feas Site


Offices (Med) 33.4 0.57 31.8 0.55 12.0 0.21

Retail (Stand Alone) 45.7 0.78 41.8 0.72 16.4 0.28

Education

(Secondary) 42.1 0.72 36.6 0.63 15.2 0.26

Hosptial 122 2.09 120.1 2.06 70.5 1.21

Hotel (Large) 89.4 1.53 85.2 1.46 56.2 0.96

Warehouse 17.6 0.30 14.8 0.25 6.4 0.11

Restaurant (Full

Service) 371.3 6.37 366.1 6.28 257.3 4.41

Apartment (Mid-

Rise) 43.5 0.75 41.9 0.72 28.5 0.49



Assessment of Learning

• What is the approximate tilt angle of a PV panel to maximize KWH of a panel?

• What is the approximate tilt angle of a an array of PV panels to maximize KWH production of a given roof area


Assessment of Learning

• What is the approximate tilt angle of a PV panel to maximize KWH of a panel? For our latitude approximately 30o

• What is the approximate tilt angle of a an array of PV panels to maximize KWH production of a given roof area? Horizontal


Design Considerations to Minimize EUIPayback

Incremental Cost of Improvement

vs.

Incremental Cost of Additional PV

Traditional: $ Installed Cost = X Year Payback

$ Savings/Yr

NZE: $ Incremental Installed Cost of Proposed Measure < = > $ Reduction in Installed Cost of PV


Design Considerations to Minimize EUITechnology

• High Efficiency Heat Pumps

• High Performance Lighting/Daylight Harvesting

• Heat Recovery/Variable Speed Chillers

• Ground Source Heat Pumps

• Demand Control Ventilation

• Phase Change Materials

• Occupancy Sensors for Setback of Temperature and OA

• Minimize SP Drop in Air and Water Systems


Design Considerations to Minimize EUIPlug Loads

• Virtual Servers• Shared Equipment• Automatically Controlled Circuit Breakers for Night Shutdown• High Efficiency Heat Pumps• High Performance Lighting• Heat Recovery Chillers• Ground Source Heat Pumps• Demand Control Ventilation• High Efficiency & Variable Speed Packaged DX• High Efficiency and Variable Speed Chillers


Design Considerations to Minimize EUIOperations

• Expand Setpoints Ranges – Temperature & Humidity

• Setback Schedules

• General Light Levels vs. Task Lighting

• Cleaning Schedules, After Hours Space Conditions

• Operating Hours for Signage

• Site Lighting Schedules

• IT Considerations

• Investment in Continuous Commissioning


Learning Assessment

• What are the (3) general categories of design considerations to minimize EUI when planning a NZE building?


Learning Assessment

• What are the (3) general categories of design considerations to minimize EUI when planning a NZE building?

• Technology (lighting, HVAC, envelope)

• Plug Loads

• Operations


Case Study 1TD Bank

Ft Lauderdale, FL

• 1 Story - 3,900 SF

• Retail Bank

• Actual EUI – 89 kBTU/SF/Yr

• 86 KW PV (roof, canopy, ground)

• LEED Platinum

• Design 2010

• Occupancy 2011


TD Bank NZE

• VRF with Dedicated OA Unit w/ Heat Recovery

• LED Lighting

• Daylight Harvesting

• R 21 Walls

• U 0.4 Glass

• R 32 Roof

• Fully commissioned, M&V plan in place

• Essentially LEED Platinum Building – Added ground-mount PV to achieve NZE


TD Bank NZE

Difficulties

• Actual plug loads 40% > model

• More Occupied hours vs. Bank Open hours

• VRF Compressor cycling

• User adjusted setpoints, customer and staff areas

• Inadequate (initially) M&V systems to troubleshoot

• Disruptions to PV generation (inverter issues)


TD Bank NZE

Corrective Action – Lessons Learned

• Evaluated all plug loads, replaced several appliances

• Added monitoring to most key groups of loads

• Replaced parking lot lighting with LED

• Set hard setback hours

• Monitoring and service of VRF

• Returned setbacks to original settings

• Month-to-month monitoring


Case Study 2Prototype BankLong Island, NY

• 1 Story - 2,500 SF

• Retail Bank

• Challenge to Achieve Class A NZE

• Maintain branding & Customer Experience

• Reasonable payback


Prototype Bank – Building Envelope Improvements

• 2”Triple Glazing (Solarban60XL) U-0.16, SC- SC-0.34

• Walls EIFS - R-51 , eliminate thermal Bridging

• Roof R-52

• Foundation R-31, eliminate Thermal Bridging


Prototype Bank – Mechanical System Improvements

• Geothermal – Ground Source Heat Exchange with Water Source Heat Pump Units

• Heat recovery for ventilation air

• Instantaneous Domestic Hot Water


Prototype Bank – Lighting Improvements

• Natural Daylighting (Solatubes & Skylights)

• Daylight Controls

• LED Light Fixtures (including signage)

• LED Site Lighting

• Maximize task lighting


Prototype Bank – Plug Load Improvements

• Data logging of all individual loads at similar bank to accurately model

• Worked with corporate IT group to minimize on-site requirements

• Evaluated every load to determine minimum quantity required

• Investigated better efficiency options for every piece of equipment

• Designed power distribution to allow automated shutdown of non-critical equipment off hours (minimize standby loads)

• Required education and coordination with IT, HR, Operations, Purchasing, and Marketing


Prototype Bank - Loads

Lighting 12,400 KWH/YrSite Lighting 3,100 KWH/YrHVAC 13,300 KWH/YrDHW 500 KWH/YrPlug Loads 30,200 KWH/Yr

Total 59,500 KWH/Yr

Projected EUI – 74.7 kBTU/SF/Yr


Prototype Bank – PV System

POWER PRODUCTION ESTIMATE 59,760 kWh/Yr

• Drive-Thru Array (126) Sanyo HIT 195w PV Bifacial Panels

• Roof Mounted Array (163) Sanyo Mono-HIP 205w Panels

• Included 25% factor of safety


Learning Assessment

• What are the key elements to maintaining net zero status of a NZE building?

Learning Assessment

• What are the key elements to maintaining net zero status of a NZE building?

• The ability to measure energy use as granularly as possible

• M&V and continuous commissioning


THANK YOU

QUESTIONS?

Documents

Planning, Design and Operation of Net Zero Energy Buildings · 2 ASHRAE RP 1651 Development of Maximum Technically Achievable Energy Targets for Ultra-Low Energy Use Commercial Buildings