Integrating Thermal Modelling in Engineering Design Services

15th May, 2016

Table of Contents• O’Connor Sutton Cronin & Sustainability

• Levels of Thermal Modelling in the Construction Industry

• Case Study – Central Bank of Ireland

• Façade Analysis

• Thermal Modelling

• System Selection

• Building Energy Rating

• BREEAM Outstanding

IRELAND, UK, WARSAW, MOSCOW, ABU DHABI, BAHRAIN, LIBYA, ROMANIA, NIGERIA

OCSC is an International Multidisciplinary ConsultingEngineering company offering a total service capability acrossCivil, Structural, Mechanical, Electrical and SustainabilityEngineering and Project Management.

OCSC has a strong reputation for design creativity, excellenceand the development of cost effective design solutions. Thecompany was founded in 1988 and over the years has grownto become a leading engineering consultancy.

The practice is managed by our group of Directors andRegional Directors, together with supporting technical,administration and information technology staff. All thedirectors are “hands on” working engineers and are involved inthe management of the projects.

OCSC has over 200 staff and along with the core Civil,Structural, MEP and Sustainability engineering services, weprovide the following in-house specialities:

• Specialist Lighting Design• LEED Assessor• BREEAM Assessors• Low Carbon Consultants• BER (Domestic & Commercial) DEC• Energy/Façade Advice• Specialists in Dynamic Assessment Modelling

Company Profile

OCSC Sustainability SectionOCSC’s Sustainability TeamPatrick FieldPatrice McVeighSinead ButlerPatrick WalsheDionysios AntypasYousaf KhalidAine DoyleDanny Dowd

Services Provided• Steady State• Dynamic Modelling• Natural Ventilation • Thermal Bridging• Wind Modelling• CFD Modelling• Daylight Studies / Right to Light• Lift Analysis• Part L Compliance (UK & Ireland)• BER and EPC’s (UK & Ireland)• BREEAM Assessments• Code Assessments• LEED Assessments

Levels of Thermal Modelling in the Construction Industry

NZEB Part L BER

Thermal envelope

specification

Maximising Daylight

BREEAM/LEED Requirements

Ventilation strategy

Reducing Primary Energy

Space Heating & Cooling Strategy

Renewable technology

analysis

CASE STUDY -CENTRAL BANK OF IRELAND

Environmental & Sustainability Targets Overview

KEY SUSTAINABLE TARGETS FOR CBoI NORTH WALL QUAY

BREEAM – EXCELLENT RATING

ENERGY PERFORMANCE BUILDING DIRECTIVE – PART L

BUILDING ENERGY RATING – BER A2

ISO 50001 – ENERGY MANAGEMENT CERTIFICATION

BUILDING ENERGY RATING TARGET (BER)

Building Energy rating is based on the following factors

• Thermal Envelope

• Thermal bridging

• Air infiltration (but no mandatory air leakage testing)

• Insulation of pipes, ducts & storage vessels

• Boiler efficiency (but condensing not mandatory)

• Chiller efficiency

• Ventilation efficiency

• Lighting efficiency

• No mandatory Renewable Energy contribution

• Avoiding solar overheating

BUILDING ENERGY RATING TARGET (BER)

TARGET BER FOR BLOCK 1 NWQ & BENCHMARKS

• 2005 - 2008 PART L REGULATIONS STANDARD

• 2013 PART L EXPECTED TARGET

• BLOCK 1 NWQ (ANGLO IRISH BANK TARGET)

• BLOCK 1 NWQ CENTRAL BANK OF IRELAND TARGET

ENVIRONMENTAL STRATEGYImprove building energy performance

Using less resources

Use resources more efficiently

Use low or zero carbon technologies where viable

Use Less Resources (Be Mean)

Optimize façades and shading

Maximize day lighting

Maximize winter time solar gains while

reducing summertime solar gains

Improving insulation levels

Improving Air tightness

Use Resources Efficiently (Be Lean)

Low Energy Plant & Appliances

Monitor energy use

Lighting control / Energy efficient fittings

District heating systems

CHP / Tri-Generation

High efficiency motors / VSD

Heat recovery

Detailed analysis of auxiliary power

Use Renewable Resources (Be Green)

Photovoltaic & Solar thermal panels

Wind turbines

Geothermal

Biomass heating

Fuel Cell technology

FAÇADE ANALYSISEnvironmental performance results

Architectural Option Existing twin skin façade design Metal self-shading design Stone frame self-shading Single skin reduced glazing option Stone face single skin option Stone face single skin option – Mixed mode.

3D representative image

Natural Ventilation resultsApplication of natural

ventilation

Original façade design based on fully sealed, air conditioned

building.

Extremely difficult to achieve adequate comfort levels through

natural ventilation with this existing façade solution.

Major alteration works to this existing facade will need to be

carried out in order to achieve required ventilation rates

Acceptable scope for incorporating opening sections within the

façade at this stage of the project.

Acceptable scope for incorporating opening sections within the

façade at this stage of the project.

Acceptable scope for incorporating opening sections within

the façade at this stage of the project.

Acceptable scope for incorporating opening sections within the façade at this

stage of the project.

Natural ventilation option changes to mixed mode scenario with exhaust fan on

each level boosting the natural ventilation levels to maintain conditions

Acoustic issues

experienced with design

Twin skin façade design offers the best acoustic performance of

all options analyzed due to the outer skin protection. This

option still offers acoustic issues in areas closest to the

perimeter openings.

Noise generated within the floor travels into the twin skin void

and enters onto the floor above and below or potentially

between meeting rooms located on each floor. A way to avoid

this is to create vertical and horizontal breaks within the façade

to avoid noise travelling between floors.

Overcoming these acoustic issues will lead to airflow and

maintenance issues

Direct noise transmission from external to internal spaces and

internal to external. This will lead to security issues and limit the

location of meeting rooms, quiet rooms, executive offices etc.

There is the potential to acoustically treat the floor void opening

and staggered screening for full height openings, however this

will lead to further openings required due to loss of aero dynamic

equivalent opening area (Free area).

Direct noise transmission from external to internal spaces and

internal to external. This will lead to security issues and limit the

location of meeting rooms, quiet rooms, executive offices etc.

There is the potential to acoustically treat the floor void opening

and staggered screening for full height openings, however this

will lead to further openings required due to loss of aero dynamic

equivalent opening area (Free area).

Direct noise transmission from external to internal spaces

and internal to external. This will lead to security issues and

limit the location of meeting rooms, quiet rooms, executive

offices etc.

There is the potential to acoustically treat the floor void

opening and staggered screening for full height openings,

however this will lead to further openings required due to

loss of aero dynamic equivalent opening area (Free area).

Direct noise transmission from external to internal spaces and internal to

external. This will lead to security issues and limit the location of meeting

rooms, quiet rooms, executive offices etc.

There is the potential to acoustically treat the floor void opening and staggered

screening for full height openings, however this will lead to further openings

required due to loss of aero dynamic equivalent opening area (Free area).

Direct noise transmission from external to internal spaces and internal to

external. This will lead to security issues and limit the location of meeting

rooms, quiet rooms, executive offices etc.

There is the potential to acoustically treat the floor void opening and staggered

screening for full height openings; however this will lead to further openings

required due to loss of aero dynamic equivalent opening area (Free area).

Maintenance issues The original concept details maintenance levels and access

walkways at each level within the twin skin. This provides

excellent access within the twin skin cavity, however

maintenance is still an issue on the outer face of the single skin

façade

Maintenance to the external façade will be complicated and it is

expected that all maintenance will be external via cranes and

hoists. The butterfly wing causes an extra concerns for

maintenance

Maintenance to the external façade will be complicated and it is

expected that all maintenance will be external via cranes and

hoists. The removal of the butterfly wing straightens up the west

façade and reduces maintenance issues

Maintenance to the external façade will be complicated and

it is expected that all maintenance will be external via cranes

and hoists. The butterfly wing causes an extra concerns for

maintenance

Maintenance to the external façade will be complicated and it is expected that

all maintenance will be external via cranes and hoists. The removal of the

butterfly wing straightens up the west façade and reduces maintenance issues

Additional maintenance will be required with the internal fans to assist in the

boosting of natural ventilation

Percentage of occupied

time where internal

temperature exceeds 28°C

Level 2 = 3%

Level 3 = 4%

Level 4 = 6%

Level 5 = 7%

Level 6 = 8%

Level 7 = 10%

Level 2 = 2%

Level 3 = 3%

Level 4 = 4%

Level 5 = 4%

Level 6 = 5%

Level 7 = 6%

Level 2 = 2%

Level 3 = 4%

Level 4 = 4%

Level 5 = 5%

Level 6 = 5%

Level 7 = 5%

Level 2 = 1%

Level 3 = 2%

Level 4 = 2%

Level 5 = 3%

Level 6 = 3%

Level 7 = 4%

Level 2 = 1%

Level 3 = 1%

Level 4 = 1.5%

Level 5 = 2%

Level 6 = 2%

Level 7 = 3%

Level 2 = 0.8%

Level 3 = 0.8%

Level 4 = 0.9%

Level 5 = 0.9%

Level 6 = 1.1%

Level 7 = 1.5%

Peak temperature

experienced within the

occupied space

36°C 34°C 33°C 29.5°C 31°C 28.5°C

Annual heat load kWhr850,452.00 1,155,487.00 1,189,254.00 1,114,578.90 1,106,845.00 1,064,948.20

Annual cooling load kWhr0.00 0.00 0.00 0.00 0.00 0.00

Annual Auxiliary load

kWhr 75,489.00 91,458.00 92,784.00 84,548.00 81,254.00 89,245.00

Annual artificial lighting

load kWhr427,288.05 415,421.00 419,921.00 581,111.75 569,717.40 569,717.40

General Services

(Computers, printers,

comms rooms etc.) kWhr

1,048,173.30 1,048,173.30 1,048,173.30 1,048,173.30 1,048,173.30 1,048,173.30

Total Energy consumption

kWhr 2,401,402.35 2,710,539.30 2,750,132.30 2,828,411.95 2,805,989.70 2,772,083.90

ElementBuilding Regulations 2008 Part L

(% Reduction)Proposed Improvements U-

Values (% Reduction)

W.m²/K W.m²/K

Wall 0.27 0.16

Floor 0.25 0.2

Roof 0.22 0.18

Windows 2.2 1.3

Infiltration 10m³/m².hr@50Pa 3m³/m².hr@50Pa

FAÇADE ANALYSIS

Thermal Modelling Assessments

CFD ANALYSIS SOLAR GAIN MODELLING

INTERNAL TEMPERATURE AND CONTROL THERMAL MODELLING

Environmental Control ModellingVentilation Principle –

Single skin stack ventilation

Predominant Wind direction

1: Incoming air through openable sections in externalfaçade

2: Exhausted air leaves open plan area into atriumspace

3: Exhaust air rises and exits through openablesections in atrium glazing

4: Prevailing wind assists in buoyancy effect causinga negative effect in internal area and pulling air outvia atrium openings

Wind rose shows the predominant wind direction duringthe summer months.

This plays a major role in the selection of openable sectionsin the Atrium opening.

Typically openings will be located on the opposite face thatthe predominant wind approaches.

This allows the wind to “pull” the warmer exhaust air fromthe atrium space.

This “pulling” motion also assists in increasing the fresh airentering through the façade openings throughdisplacement of air.

Environmental Control ModellingOption J Natural Ventilation results: Air temperature

Level 2: Level 2 experiences an excellent level of fresh air into the space. Level 2achieves the highest air change rate due to the height difference between the incomingair and the exhaust air outlet at level 8 (Stack effect). Temperatures reach a maximumof 28°C for 2 hours on the warmest day of the year.

Level 3: Level 3 performs much the same as level 2 maintaining a reasonabletemperature profile across the floor plate.

Level 7: Level 7 experiences the worst summertime internal temperatures. This is dueto the minimal height difference between the incoming air and the exhaust air outlet.All of the lower level floors exhaust air combines at this spot within the atrium beforeexiting the space.

Element of Energy Modelling

• Daylight Sun path analysis for varying seasons

1st of Jan 15th June

• Minimised Solar gain during summer months

• Maximised daylight

Thank you for your Time