Green Building & Measurement Challenges (Instrumentation for Monitoring Central Chiller Plant Efficiency)
Francis Tay Principal Manager
Green Mark Department Building and Construction Authority
Singapore
Agenda • Singapore’s Green Building Master Plan • Hallmark of Green Mark: Chiller Efficiency • Measurement & Verification
– Standards and Requirements – Instrumentations – Pitfalls and Lessons Learnt
• Smart Chiller Efficiency Portal
The BCA Green Mark Programme – A cornerstone of our green polices and
initiatives
Climate Resources
Wellbeing Ecology
4 Sustainability Outcomes
5 Focus Areas
Climate Responsive
Design
Building Energy
Performance
Resource Stewardship
Smart and Healthy Building
Advanced Green Efforts
Singapore’s Green
Building Journey
BCA-NParks Green Mark for Existing Parks BCA-NParks Green Mark for New Parks
BCA Green Mark for Infrastructure BCA Green Mark for Districts
BCA-LTA Green Mark for Rapid Transit System
A Suite of BCA Green Mark Schemes
BCA Green Mark for Non-Residential Buildings BCA Green Mark for Residential Buildings
BCA Green Mark for Landed Houses BCA Green Mark for Healthcare Facilities
BCA Green Mark for New Data Centres Version 1.1
BCA Green Mark for Non-Residential Buildings
BCA Green Mark for Residential Buildings BCA Green Mark for Existing Schools
BCA Green Mark for Office Interior BCA Green Mark for Restaurants
BCA Green Mark for Supermarkets BCA Green Mark for Retail
BCA-IDA Green Mark for Data Centre
New Buildings Existing Buildings
Beyond Buildings
Within Buildings
Singapore’s Green
Building Journey
2005 2010 2018 2020 2030
>34% Green Buildings
> 13% Green Buildings
>50% Green Buildings
>80% Green Buildings
< 0.1% Green Buildings
~3200 building projects have met Green Building Standard
~ 94 million m2 green GFA
Green Building Achievements and Accolades
Ranked 2nd in Top 10 Global Cities for
Green Building 2016
International Star of Energy Efficiency
Award 2013 1st country outside America & Europe to win
WGBC Chairman’s Award 2015
Singapore’s Green
Building Journey
Aspen Institute Energy & Environment Awards 2010
Focus New Buildings
Focus Existing Buildings
Focus Occupants and Tenants
Launched BCA
Green Mark Scheme
2005
2008 2006
Legislation on Environmental
Sustainability for New Buildings
2011
Established the Singapore Green Building Council
Launched BCA Centre for
Sustainable Buildings
Legislation on Environmental
Sustainability for Existing Buildings
2012 2013
Launched BCA Building Energy
Submission System
2014 2015
2009
Developing the Green Building Eco-system through Comprehensive Plans
& Policies
Singapore’s Green
Building Journey
80% of all buildings (by gross floor area) to meet Green Building Standard by 2030
Approach to Green Buildings 1. Passive strategies (Climate positive) – to implement as a first priority!
• Natural Ventilation
• Behavioural changes
• Daylight
• Operation and regular maintenance
2. Active Systems – with high efficiency to support or supplement the passive measures. E.g. Energy efficient AC, lighting and low flow water fittings
3. Renewable Systems
Air-conditioning with Chiller Plant
Green Mark Rating
Peak Building Cooling Load (RT)
< 500 ≥ 500 Efficiency (kW/RT)
Certified 0.85 0.75 Gold 0.80 0.70
GoldPlus 0.75 0.68 Platinum 0.70 0.65
Existing Building New Building
Minimum System Efficiency of Water-Cooled Chilled Water Plant
Green Mark Rating
Peak Building Cooling Load (RT)
< 500 ≥ 500 Efficiency (kW/RT)
Certified 0.80 0.70 Gold 0.80 0.70
GoldPlus 0.70 0.65 Platinum 0.70 0.65
Business Case of Retrofitted Existing Buildings
Measured m²/RT Range Average
Office Buildings (58 projects)
35 – 65 48
Hotels (32 projects) 36 – 88 58 Retail Buildings (28 projects)
18 – 38 27
Benchmark Cooling Load of Office Building
Why Accurate Measurements of Chilled Water Plant Efficiency?
• Chiller plant system accounts for the highest electrical consumption in all commercial buildings
• Small temperature difference between supply and return chilled water temperature
• Making the most out of the Building Automation System • Used as an accountability tool to gauge the performance of
the supplied equipment post installation • You can only improve what you can measure
14
CHWS Temp CHWR Temp DT Temp CHW FlowCooling capacity
Elect power input Efficiency
C C C L/S tons Kwi Kwi/tonActual performance 7.00 12.00 5.00 168.2 1000 780 0.780Error in temp -0.50 0.50Claimed performance 6.50 12.50 6.00 168.2 1200 780 0.650
0.130% error 16.7%
Error in efficiency
Ave Cooling capacityAnnual
operating Hrs Cooling loadError in
efficiencyError in energy
savings Tarrif rateError in energy
savingstons Hr ton-hr kwi/ton KWH $/KWH $
1,000 8760 8,760,000 0.130 1,138,800 0.20 227,760
14
50% of a chiller
+/- 0.5C temp error results in +/- $228K saving error!
Impact of Poor M&V
Permanent Instrumentations of Central Chilled Water Plant
Provision of permanent measuring instruments for monitoring water-cooled central chilled-water plant efficiency. The installed instrumentation shall have the capability to calculate resultant plant efficiency (i.e. kW/RT) within 5% of its true value and in accordance with SS591 – Code of Practice for Long Term Measurement and Verification for Water-cooled Chilled Water Plant Systems.
The individual uncertainty of each measurement system - mass flow rate (by flow meter), electrical power input (by power meter) and the temperature difference (by temperature sensors) are as follows :
Error Budget
Item Measurement System (includes sensor and data
acquisition system)
End-to-End Measurement Uncertainty
(% of reading)
01 Flow 1% see note (1) + 1% (i.e. 2%)
02 Power 2%
03 Temperature sensors with accuracy of ± 0.05°C @ 0°C
1.3% see note (2) Temperature difference (ΔT)
Note: (1) An additional 1% to be included in the computation of measurement errors for flow meter. (2) The measurement error (%) for temperature sensors is calculated based on the Root Sum Square error for the 2 temperature
sensors for the design or actual delta T (i.e. ΔT). In this case, Temperature sensors with accuracy @ 0°C = ± 0.05°C Design/ Actual ΔT = 5.5 °C Measurement errors for ΔT = √(0.052 + 0.052)/ 5.5 °C x 100% = 1.3%
Error Budget (Cont’)
Based on the above information, the overall uncertainty of measurement is as shown in the following :
where UN = individual uncertainty of variable N (%) N = mass flow rate, electrical power input or delta T Errorrms = √ (∑ (UN)2) = √ (22 + 22 + 1.32) = 3.1%
Therefore, the total uncertainty for the calculated chilled-water plant efficiency (kW/RT) is 3.1% which falls within the 5% of the true value.
Error Budget (Cont’)
Permanent Instrumentations of Central Chilled Water Plant (GM2015 for New Development)
• Location and installation of the measuring devices to meet the manufacturer’s recommendation • All data logging with capability to trend at 1 minute sampling time interval, and recorded to the 3rd
decimal digit • Flow meters are to be provided for chilled-water and condenser water loop and shall be full bore
ultrasonic / full bore electromagnetic type of 1% uncertainty or equivalent. Electromagnetic flowmeter shall be capable of electronic in-situ verification to within ±2 % of its original factory calibration
• Temperature sensors are to be provided for chilled water and condenser water loop and shall have an end-to-end measurement uncertainly not exceeding ±0.05°C over the entire measurement or calibration range. All thermo-wells shall be installed in a manner that ensures the sensors can be in direct contact with fluid flow. Provisions shall be made for each temperature measurement location to have two spare thermo-wells located at both sides of the temperature sensor for verification of measurement accuracy
• Dedicated power meters (of IEC Class 1 or equivalent) and associated current transformers (of class 0.5 or equivalent) are to be provided for each of the following groups of equipment: chillers, chilled water pumps, condenser water pumps, cooling towers, condensing units, AHUs and PAHUs
Class 1 in GM2017 for Existing Buildings
Thermistor RTD A mixture of metals and metal oxide
materials. Ceramic Wire Wound & Thin Film
10 K Ohms at 25° C, … 100 Ohms @ 0° C, …
Steinhart and Hart Equation Callendar-Van Dusen equation
Example of Temperature Sensor Installation
Example of Temperature Sensor Installation
Heat Balance Substantiating Test Verification of central chilled water plant efficiency: Heat balance – substantiating test for water-cooled central chilled water plant to be computed in accordance with AHRI-550/590
The heat balance is represented by the following equation:
qcondenser = qevaporator + Winput where,
qcondenser = heat rejected qevaporator = cooling load Winput = measured electrical power input to compressor
Heat Balance Substantiating Test
Condenser
Evaporator Motor
Gear
KWinput
Energy in = Energy out
Oil heater
Cooling Load
Heat rejected
The computation of the percent heat balance (see formula below) that is the total heat gain and total heat rejected must be within ± 5% for 80% of the sampled points over the normal building operation hours.
Percent Heat Balance =
Note: For open drive chillers, the Winput shall take into account the motor efficiency provided by the manufacturer.
An example is provided as follows: Input power (measured) = 100kW Motor rated efficiency (η) = 90% Adjusted Winput = 100kW x 90% = 90kW
Adjusting for Open Drive Chillers
(qevaporator + Winput) - qcondenser qcondenser
x 100% ≤ 5%
In the event where hydraulic losses of pumps constitute a substantial heat gain, these losses have to be properly accounted for. The value shall be determined from pump efficiency values provided by the manufacturer. An example is illustrated as follows:
Motor input power (measured) = 30kW (A) Motor rated efficiency (η) = 90% (B) Pump rated efficiency (η) = 80% (C) Hydraulic losses = (A) x (B) x [(100% – (C)] = 30kW x 90% x (100% - 80%) = 5.4kW Adjusted Winput = kWi (chillers) + 5.4kW
Heat Balance Substantiating Test
Worked Example (Variable Primary Flow)
A: qevaporator = FM1 x Cp x (CHWR - CHWS) B: qcondenser = FM2 x Cp x (CWR - CWS) C: Winput = kWi-1 + kWi-2 + kWi-3 where Cp = 4.19 kJ/kg.°C and density of chilled water is assumed to be 1kg/l Percent heat balance = [(A + C) – B] / B x 100% Note: In the event where heat balance exceeds ±5%, hydraulic losses of pumps constituting substantial heat gain can be included on the right hand side of the heat balance equation. The value of which shall be determined from certified gear losses and pump efficiency values provided by the manufacturer.
Temperature Sensor Flow Meter Power Meter + CT Data Acquisition
Installation Location & installation of measuring devices to meet manufactures’ recommendation
Direct contact with fluid flow
Measurement Uncertainty
1.3% 2% 2%
Location - Chilled water supply header(s) - Chilled water return header(s) - Condenser water supply header(s) - Condenser water return header(s)
-Chilled water supply/return header(s) - Condenser water supply/return header(s)
-Chiller(s) electrical panel(s) - Chilled water pump(s) electrical panel(s) - Condenser water pump(s) electrical panel(s) - Cooling tower(s) electrical panel
Type -Thermistors - RTDs
- Full bore magnetic - Ultrasonic (conditional)
- Digital power meter - Datalogger + Gateway - DDC(s) - BTU meters
Others 2 spare thermo-wells at each measurement location
Electronic In-situ verification 1 minute sampling interval
Summary
Desktop M&V Setup
COMMON MISTAKES Site Installation
Location of Permanent Instrumentation
Small Chillers Big
Chillers
< 5D
Situation Problem Location of flowmeter less than 5D recommended distance from bend
Might not accurately measure flow readout
Location of temperature sensor too near mixing point
High fluctuation in temperature readout
Location of Permanent Instrumentation
Situation Problem Location of thermowell with opening facing a pipe.
Not enough space “straight length” to insert thermistor probe into the thermowell
Location of Thermowell
Situation Problem Location of flowmeter and temperature sensor before and after bypass pipe
Might not accurately measure building cooling load
Location of Permanent Instrumentation
< 5D
Situation Problem Location of flowmeter less than 5D recommended distance from bend/reducer/expansion
Might not accurately measure flow readout
reducer
Location of Permanent Instrumentation
Vertical Position Easily accessible for maintenance, but there is water impact (NOT a good choice)
Installation at 135° & 225° Position It might collect condensation water If there is leakage from the test plug, there will be water pool
Too near to the chiller
Avoid installation near to a chiller
Heat Balance is Off • Low flow + Long Pipe • Sensor Location
Heat Balance is Off
e.g. fluctuating flow due to on-off valve
Continuous Commissioning
Continuous or monitoring-based commissioning is required for persistent high performance
Chiller Efficiency Smart Portal • Continuous monitoring • Trend Analytics to spot performance variance • Autonomous alarm
Periodic Energy Audit Continuous Monitoring
Efficient Effective Empower
What it isn’t
Data Collection • Light-touch, Risk-free, Universal
– Will not disrupt operations – Does not exert control nor command
• Chiller Sensor Data – To compute efficiency (kW/RT) – Leverage existing instruments
• 4 means – Export from BMS , then upload – Via a BACnet gateway – Via a Modbus gateway – Via a software interface to BMS
BCA Portal
Internet
Feed-in Feed-in
Direct from Building
Remote Service Provider
Owners’ Ops Centre
Smaller, MCST Buildings
BCA Smart Chiller Portal
• Light-touch, Light-weight and Universal • BCA
− Publish the interface and installation examples
• Building Owners − Direct feed, or − Feed in from their Integrated BMS or Command Centre
• Portal Service Provider − Feed in for their subscribers
Chiller Portal
1. File Export 4. iBMS / Portal Service Provider HTTPS
HTTPS HTTPS
HTTPS
2. BACnet Gateway 3. Modbus Gateway
REST API
BCA Smart Chiller Portal Standardised Data Interface
Title REST API to insert chiller plant raw data (Draft)
URL http://bca_cesp.portal.com/api/ImportRawData
Method The request type - POST
URL Params Not Required
Data Params [ { "BuildingId": "buildinga", "ObjectId": "chiller", "ObjectNo": "1", "DataFieldId": "power", "Value": "110", "Timestamp": "2016-01-16 02:15:01", "Key": "secretkey" },
{ "BuildingId": "uwctamp", "ObjectId": "chiller", "ObjectNo": "1", "DataFieldId": "SupplyTemparatue", "Value": "110", "Timestamp": "2016-01-16 02:15:01", "Key": "secretkey "}, ]
Success Response Code: 200
Error Response Code: 400, if buildingId not valid Code: 402, if building object datafield mapping not valid Code: 403, if secrectkey for that building is not correct Code: 404, Other problem
Notes
BCA Smart Chiller Portal Standardised Data Interface (in Green Mark 2017 Appx A)
BCA Smart Chiller Portal User friendly & Intuitive Dashboard
BCA Smart Chiller Portal Efficiency Breakdown
BCA Smart Chiller Portal Generate Energy Audit Report
BCA Smart Chiller Portal Analysis for Trouble-shooting
BCA Smart Chiller Portal Baseline & Alert Rules
Dashboard Event List
BCA Smart Chiller Portal Mobile App
Walking the talk for Smart FM – Performance-based for Existing Buildings
Higher value proposition – Continuous commissioning to sustain performance
– Data-driven Productivity tool − Manage by exception
– Simplify Re-certification & Legislation − Facilitate GM Re-Certification & 3 Yearly Energy Audit
− Less bureaucratic and paperwork
− Lower cost of compliance
Re-inventing Green Mark with Smart Chiller Portal
