Building Tuning Using Simulation A Practical Case

Building Tuning Using

Simulation – A Practical Case

Study

Matthew Webb

Sustainability Consultant,

Umow Lai Consulting Engineers

Australasian Building Simulation Conference

Melbourne, November 2017

engineering sustainable

environments

Contents

▪ UFAD introduction

▪ Simulation role and objectives

▪ Methodology

▪ Simulation results and interpretation

▪ Operations and tuning

▪ Effects and monitoring

▪ AHU controls tuning

▪ Limitations and further improvements

▪ Key outcomes and conclusion

Matthew Webb – Umow Lai & The University of Melbourne

Everyone relaxed?

Matthew Webb – Umow Lai


Image: grocon.com

Matthew Webb – Umow LaiImage: umowlai.com.au


Images: peterbennets.com

Matthew Webb – Umow LaiImage: grocon.com



Matthew Webb – Umow LaiImage: Matt Webb


UFAD introduction

What is Under Floor Air Distribution


WOW! Air is

coming out

of the floor!

This UFAD thingy is

amazing! You should

come check it out!

This view is soooo much

better with UFAD!

I’m a diffuser

Yeah, although I’d wish

someone would finish it! The

floor is really becoming an

OHS issue

Pixel


Queensberry St, Carlton

Architect: Studio 505

Highest LEED Rating in the world

Perfect 6 Star Green Star

Sustainability Rating

171 Collins St


Architect: Bates Smart

Premium grade office building

6 Star Green Star Sustainability Rating (Office v2)


I am so

cool!

I wish I was

that cool

150 Collins St


▪ Architect: Peddle Thorp

▪ Builder: Grocon

▪ 20,000 m2 Net Lettable Area

▪ Westpac Banking Corporation as major tenant

▪ 13 floors

▪ 5 Star Green Star Sustainability Rating

▪ 6 Star NABERS Operational Energy Rating

▪ Currently in Defects Liability Period


Gooooood

morning

Melbourne!!

GSO Dandenong


Architect: Hassell

NLA: 14,500 m2

6 Star Green Star Design and As Built Ratings (v3)

5 Star NABERS Energy

6 Star NABERS Water


Simulation role and objectives

Purpose of BES

Inform architectural and services design.

Testing energy initiatives.

Ensure the building would be capable of achieving performance ratings.


Rating Target

Green Star 5.5 Star

NABERS Energy 4.5 Star

NABERS Water 5.0 Star


Methodology


Translate design docs into BES

Simulate

Complete Design

Redesign

Green Star Submissions

Performance Targets

Construction

Meet objectives?

Yes

No

Commissioning

BenchmarkingTuning


Reverse benchmarking

Start with the simulation results.

Calculate the percentage contribution of each of the services on an annual basis (ps,a).

Find the overall required benchmark, e.g. NABERS reverse calculators (Nbenchmark).

The target for each building service becomes Es,a.


Es,a = ps,aNbenchmark

Additional divisions

Benchmarks adjusted into monthly, daily and hourly budgets.

Weather-dependent services were divided by month as a balance between accuracy and simplicity.

The specific breakdown of percentage contribution to the overall total is a factor of the specific building and its location.

Detailed and specific energy modelling was therefore a key contributor to the development of benchmarks.


Es,m = ps,mEs,a = ps,m ps,aNbenchmark( )


Simulation results and interpretation

Tuning Targets


RatingGas benchmark

[MJ]Electricity benchmark

[kWh]

4.5 Star 1,813,264 1,038,365

5.0 Star 1,344,417 769,880

5.5 Star 1,008,312 577,410

Using the correct

inputs for area and

hours…


Building service4.5 Star NABERS Simulated Target

5.0 Star NABERS Simulated Target

Electricity [all kWh]

Lighting Ground - L7 130,834 97,005

Lighting Basement 39,458 29,255

Chiller 249,208 184,771

AHU fans and Fan Coil Units 320,855 237,893

Pumps 88,261 65,440

General Exhaust (including car park ventilation) 92,414 68,519

Lifts 34,266 25,406

Rainwater and stormwater pumps 62,302 46,193

Security, communications and other general power 20,767 15,398

Annual Total [kWh] 1,038,365 769,880

Natural Gas [all MJ]

Boiler [MJ] 1,529,101 1,133,729

Domestic Hot Water [MJ] 284,163 210,688

Annual Total [MJ] 1,813,264 1,344,417



Operations and tuning

Why building tuning?

▪ Close monitoring of building energy consumption allows facility managers and service technicians to understand where faults are occurring and to highlight opportunities for further improvement.

▪ Facility managers can correct faulty controls or repair plant before malfunctions have a large impact on overall (and official) rating status.

▪ Feedback is provided to track against required targets, e.g. NABERS. The extra visibility provides confidence that the building is meeting required performance levels.

▪ If building performance is poor, there is time to improve before the next official rating is due.






Effects and monitoring

Some actions to date…


Service Observation Outcome

Lighting

Public holiday consumption matches business day consumption.

Controls adjusted to account for public holidays (this has required constant resetting during building lifetime).

LightingDaily use high in common areas.

Reset light timers to 15-minute intervals. Halogen fittings replaced with LEDs.

LiftsOver-use of heavy duty goods lift.

Staff advised to use passenger lifts only, resulting in a decrease in lift energy.

AHU Fans and heating

Over-consumption during heating.

Supply air temperatures increased in UFAD system. Fan energy decreased.

Car park ventilation

Excessive consumption (up to 10 times expectations).

New controls regime written to more strictly control fan operations based on carbon monoxide control. Energy consumption now 5% of initial start up consumption.


AHU Controls Tuning

A deeper look

▪ High fan consumption recognised as a potential area for improvement.

▪ Additional temperature sensors were installed and detailed logging was conducted.

▪ Initially, stratification measurements indicated that the temperature gradient between floor and ceiling could be increased.

▪ Control changes were implemented to AHU off-coil temperatures and to increase the control range of VCDs.

▪ Improvements in energy consumption were noted, but further improvement was definitely possible.

▪ Eventually, it was determined that a variable pressure reset offered the greatest benefit-to-cost ratio.



BenchmarkConsumption below benchmarkConsumption above benchmark


BenchmarkConsumption below benchmarkConsumption above benchmark


Year MonthPrevious year’s consumption

[kWh]

Current year consumption [kWh]

Comparison to previous year

2016 December 22,985 10,564 -54.0%

2017

January 19,867 11,269 -43.3%

February 22,100 8,324 -62.3%

March 21,690 11,339 -47.7%

April 20,158 5,667 -71.9%

May 24,279 11,534 -52.5%

June 24,065 11,853 -50.7%

July 24,399 11,657 -52.2%

August 26,666 10,868 -59.2%

September 23,250 9,989 -61.3%


Limitations and further improvements

Where can we go from here?

▪ Increase the accuracy of the weather data.

▪ Develop benchmarks and estimates for future climate.

▪ Continue to monitor the accuracy and suitability of the benchmarks.

▪ Fine tune the inputs such as operational hours for occupancy, lifts and lighting.

▪ Reflect system improvements.

▪ Develop BIM integration.

▪ Pay closer attention to how building systems – especially HVAC – are controlled in building simulations.



Key outcomes and conclusion

Did we learn anything?

▪ Building tuning via simulation is methodologically simple, but can technically be a challenge.

▪ HVAC controls are critical in developing benchmarks and testing opportunities for improvements.

▪ Data integrity is paramount.

▪ At GSO, the integration of as built and commissioning data provided a foundation to develop services benchmarks.

▪ Initiatives have been progressively introduced during building operation to maintain and improve the NABERS Energy rating, despite increased building use and occupancy.

▪ Variable pressure reset proved to be a success, now the building is aiming for 5.5 Stars.


Something

about “details”

and “devil”

Building Tuning Using Simulation A Practical Case

Documents