Glazing 918 Darwin Apartments in a Single LEAP

G.James Glass and Aluminium - Transport DivisionStage 2 of the Australian Defence Force’s accommodation upgrade to their Single Living Environment and Accommodation Precinct (LEAP) in Darwin saw the construction of 918 new apartments. It was a highly organised development that had strict protocols and required innovative task management to accomplish the project.

This upgrade will improve and better integrate the living standards and communities where single defence personnel reside. The project is being managed by the Plenary Group, recognised as international specialists in providing whole community concepts, with Woods Bagot as the architect.

G.James Role

G.James Glass and Aluminium’s Darwin office successfully negotiated the contract to supply and fit glazed windows, door frames, security doors and louvres to the various planned concepts in two locations – Larrakeyah (in the city) and Robertson (rural). Each site had individual acoustic, thermal (energy efficiency), wind loading, water penetration and bushfire requirements which formed part of the specification. To ensure compliance, G.James undertook  product modifications, the development of new systems and conducted testing for the intended suites. The contract is to be achieved in two phases of supply and installation that span over 1 ½ years.

G.James is organised to take on projects of this scope. Divisions including business support services and transport are combined with a large workforce and the latest technology to fulfil the resource requirements of larger ventures. For the Darwin project, initial discussions internally located potential branches with facilities and personnel available. Once the project was awarded, managers designated the resources available to meet the commitments.

Design

Darwin comes with stringent water and wind pressure requirements.  Product testing was needed for the new 472 Series door framing system and the 246 Series sliding door for Darwin’s conditions.

Energy efficiency was addressed using IGU’s.  This also helped resolve the acoustics issue at the Robertson location, as there was a flight path located overhead.

BAL Rating

Bushfire ratings are addressed at the Robertson location due to the proximity to bushland in its rural setting.  A Bushfire Attack Level (BAL) rating is given to an area or facade to determine the requirements of the materials used.  Glass and gaskets are selected that comply with these conditions from the G.James BAL Manual.

The BAL ratings applied to G.James materials have been determined from AS3959 as “Deemed to satisfy” or the prescriptive method.  The prerequisite for the physical properties of glazing materials in bushfire prone areas is to resist ember attack and radiant heat transfer.  Your local branch or G.James representative can give you further information on BAL compliant products available.

Implementation

The work was divided up in accordance with the capabilities and current workloads of various branches. Some were accustomed to this volume of work, and others were introduced to it.  The branches involved are outlined as follows, with a brief summary of the who they are, and a quote about what this project entailed for them:

Head Office

Initially, the Business Support Service division at G.James’ Head Office assisted the Darwin branch with project specific engineering, product design, contract administration and material / production coordination.

“This included a review of the products to create efficiencies in product manufacture and installation. Because of the distance that products were to travel by road, we also orchestrated the design of several specific packing crates.” – John Staunton (Manager of Business Support Service).

G.James’ Head Office is charged with the role of being the central point of direction for the branches with regards to technical advice, administrative services and major project logistics & coordination. This responsibility is assisted in the fact that the Head Office is in close proximity to the Group’s major manufacturing facilities at Eagle Farm.

Maroochydore Branch

Maroochydore supplied the entry door frame, highlights and sidelights made with the new 472 Series, as well as Crimsafe screens.

“For 12 months, the Darwin Defence Accomodation has been keeping our commercial and Crimsafe departments with a constant flow of work. The Emmegi CNC machine has been vital part of the processing for the doors required on this project” – Darren Mahoney (Branch Manager)

Bundaberg Branch

Bundaberg worked on 475 Series fixed louvre grill and top hung sliders, Crimsafe screens for the 246 Series sliding doors, and 475 Series hinged Doors.

“It has been amazing to see the various number of branches working together to have all items made, packaged and then transported to Darwin (without damage) ready for installation all within the tight time frames. “ – Damian Perry (Estimator)

KDC

KDC (or the Knock Down Components factory in Brisbane) cut and processed assembly kits for the 246 Series sliding doors.

“We have only had to replace two door frames due to transit damage which demonstrates our attention to detail and ability to supply component parts to the correct specification on time to allow for efficient project management ongoing.” Jason Claridge (Branch Manager)

KDC typically make standard glazing packages for nationwide distribution.

Riverview

Riverview provided framing for the 472 Series fixed glazing and hinged doors.

“Riverview are accustomed to national distribution, being the only manufacturers of double hung windows, so coordinating this project was not out of character.  It did allow us to contribute our other skills and it was fantastic to be a part of such a combined effort.” – Ben Driessen (Branch Manager)

Along with Double Hung Windows, Riverview have a stock of unusual glass types and patterns that are invaluable to replacing period style glass.

Woodridge

Woodridge took care of the 048 Series fixed and awning windows.

“The scale of work for this job saw our manufacturing processes streamlined. It is good to know just how much work we are capable of doing.” – Garry Fulton (Branch Manager)

Woodridge produces almost all products made by G.James products (except double hung), and services the area from south of the Brisbane river to the top of the Gold Coast and out to Manly and Redland bay. They also make a lot of commercial products for Western Australia, and supply 048 series hopper windows to other branches and departments.

Glass Department

The Glass Department in Brisbane manufactured all the glass for the project.

“Our glass department is built to take mass orders of this size, so implementing it was not a problem.  It is good to work on this scale of project, knowing we are contributing to such a large G.James effort.  It is what makes G.James the company we are – we have the ability to take on this kind of work as we have the most sophisticated and modern technology available to us.” – Tony Evans (Operations Manager)

The sizeable glass operations produce many different types of glass – from sizing annealed, coated and tinted, to manufacture of laminated, toughened, printed, patterned as well as IGU’s.

Mechanical and Transport Division

Mechanical and transport departments provided transport for all the components to be brought to Brisbane for coordination and shipping to site.

“We coordinate this type of work all the time – the volume of this job was quite large, however, and meant strict management of delivery – the right products at the right time.” – John Erskine (Transport Manager)

Transport run a fleet of trucks up and down the East Coast of Australia (Sydney to Cairns) to service delivery of the full range of G.James products.

Darwin

Darwin – project coordination and implementation.

” We would never have been able to pull it off without the support of all the other branches that got involved and helped us make this job a reality. To everyone – thanks, it was greatly appreciated.” – Scott Harris (Branch Manager)

On Site

The products, when ready, were transported to Darwin, and fixers were sub contracted to carry out the vast workload at installation.   Attention to detail was essential as all the glass for this project was site fitted because of additional fixings in the glazing pocket required to meet the high local wind loads.

Project status

The project is in its final stages, and is projected to be complete by the end of this year (2013).  Coordinating our resources to achieve higher rates of product supply is not a new service performed by G.James.  We are capable of performing this kind of logisitical coordination to make this scale of projects feasible. G.James welcomes discussion to assess how we can provide solutions for any similar large projects.

Eagle Farm Bus Depot – A G.James All Rounder

G.James, Gossi Park and QuickAlly Access Solutions at the Bus DepotA project showcasing the many products G.James Glass & Aluminium and affiliates produce, is due to open next week. Facets of the G.James organisation, including metal fabrication, Gossi Park & Street Furniture, glass and QuickAlly Access Solutions scaffolding, have made their own way to be part of a humble bus depot.

The Eagle Farm Bus Depot has been recently constructed on Schneider Road in Brisbane. It spreads out over a large area that is mainly car park, or bus park, for the automotive fleet. The industrial surrounds of the location require an outdoor area that is visually protected, yet bright and airy. These qualities were put in place by architects Nettleton Tribe and built by Adco, with landscape work sub contracted out to Penfold Projects.

Setting the scene in an industrial neighbourhood

The brilliant colour of the louvres dominates the skyline, blocking out the surrounding visual hubbub of transport. The powder coat colours chosen, Dulux Duratec Intensity Yellow and Interpon Ultriva Sensation Gloss orange stand out from the background colour, Dulux Zeus Silver Grey. They are randomly alternated, and square and elliptical profiles were used to enhance the arbitrary nature of the feature screens.

The south side of the building uses horizontal louvres. It overlooks the parking spaces for the buses.  The horizontal lines making it easier to see through these to monitor the movements of the buses coming and going, while still allowing the colour and striation to make a visual impact.

The north side of the building has an outdoor seating area that uses vertical louvres as a fence like barrier. They vary in height to follow the incidental theme, making the area less formal and lending more interest.

Quick Solutions

G.James Joinery or Light Metal Fabrication Department won the tender through Adco to coordinate the design, manufacture, production and installation of the louvres.

The on site installation was sub contracted to a company that utilise the QuickAlly aluminium mobile towers scaffolding system. They used this to access the top of the posts and higher louvres (or higher end of the louvres in the vertical areas). It was an ideal situation for the mobile scaffolds, as their height is adjusted simply to meet the level of the work area. They are lightweight and able to be manoeuvred easily along the louvres providing a safe, secure platform to do the installation from.

Creating atmosphere

The finishing touches, to make the place welcoming and user friendly, were provided by Gossi Park & Street Furniture. Gossi’s products were specified by the architect, Nettleton Tribe, and were coordinated through Penfold Projects.

21 settings are scattered in two areas, using Access Tables and Parkway Seats. Access Table are disability compliant, and positioning of the Parkway seating allows enough space for wheelchair use.

The “planks” of the furniture have been powder coated a reddish brown for a timber look – a colour called Headland. The frame and legs are powder coated Shale Grey – a matt metallic look. Using aluminium planks provides a longer lasting, low maintenance product, and the powder coat will allow it to retain its original look. Please note, these products are in shaded areas. Using powder coat in the sun can cause the products to heat up to uncomfortable levels.

There are four BCC waste bin enclosures to house garbage bins provided – two to each area for recycling and general waste. They are ideal for concealing waste, and easy to empty. They are the preferred bin used by the Brisbane City Council for their ease of use and stylish design. The furnishings and landscaping of the area exudes a pleasant vibe for professionals to take time out and congregate.

A glass choice that is no surprise

On site another sub contractor has independently chosen our product for use in the buildings glazing. The overall impact of all the products that have come together under separate circumstances is a delightful find. It is good to know the quality and professionalism of G.James service and products are utilised and appreciated by many, and can come together in jobs such as these for some spectacular results.

New Glazing Product: Low E Coated Glass Launch

Solarplus TLE 62 new glass product

G.James Glass and Aluminium pride ourselves on being at the forefront of the latest product developments and are proud to offer a new range of high performance Low E coated glass products, Solarplus TLE62. This new range of coated glass will be incorporated into G.James TwinGlaze Insulated glass Units and will supersede the current range of Solarplus Low E products offered.

Benefits

Low E glass has a range of distinct benefits – the major function is to provides better thermal performance. The new Solarplus TLE 62 glass produces results in an efficient method, requires shorter lead times for production, and is ideal for jobs large or small.

Solarplus TLE 62 has high visible light transmittance and neutral appearance in both transmittance and reflectance which is low internally and externally.  Please refer to the performance table below for data, and please note, this is for glass only performance. Contact G.James for whole of window data.

Solarplus TLE 62 new glass product

The thermal performance is excellent with low U Values and Solar Heat Gain figures.

Colour Options

The Low E coating is on clear glass and can be combined with tinted glass to provide different aesthetic qualities. The range includes:

  • Grey
  • Green
  • Bronze
  • Blue
  • Super Green

The Solarplus TLE 62 is a durable coating that is able to be heat treated for toughening where it is required.

The G.James manufacturing facilities are currently being upgraded, and this product will be available in October, 2013. Please contact us with any further enquiries about this new product range.

Gasworks – A Modern Development with a Heritage Heart

Gasworks building developmentOngoing development of a historical site located at Newstead (Brisbane), sees it transforming in stages to a new mixed use precinct. The name derives from the sites original use – the gasworks, and part of the project is to protect the heritage listed gasometer located prominently amid the gasworks buildings.

Originally built in 1863, the gasometer once stored gas in a large bladder contained within its frame work.  The Gasometer has been fully restored ensuring the ornate pinnacles and lace work beams stand as equal alongside its newly constructed neighbours.  It creates a unique contrast set amidst the strong lines and bold shapes of the modern architectural features of the Gasworks building development.

Designed by the same team that worked on the adjacent Energex building – Architect Cox Rayner and builders FKP, the buildings in this phase of construction comprise of Building A on Skyring Terrace (five storeys) and Building E on Longland St (three storeys).

G.James Role

G.James Glass and Aluminium supplied and installed glazing facades, doors, windows and some extruded sun hoods. Building A has a proposed 5 star green star rating – so energy efficiency, acoustics and air infiltration were important design factors. As such, products with proven test results were selected for use.

Building A

Building A comprises ground floor shop front retail with four upper levels of offices. The offices utilise the flush glazed 651 series glazed with IGUs made up of green glass with a low E coating for energy efficiency, a 12mm air space, and 6mm clear glass internally. This also assisted in achieving a better acoustic rating.  Spandrel panels were made with a green ceramic painted surface – a premium spandrel glass option  that maintains the look set by the vision area.

Building E

Building E was a combination of two levels of residential apartments along Longland Street, two levels of office space along the breeze way between the buildings, and a retail shop front precinct on the ground level. The offices in building E utilize the 650 series, also flush glazed, but to accommodate 11.52mm laminated glass. The glass has a low E coating and the same colour, but didn’t require the same level of acoustic rating or energy efficiency. The office glazing also incorporated architectural features such as glass fins for extra strength and sun hoods for protection.

The residential apartments use a range of glazing styles. Fixed framing used the 650 series system with 265  series awning windows spaced across the facade. Balconies feature four side supported 550 series balustrades with access through 445 series sliding doors.

Shopfront Design Problem

The retail areas required a centrally glazed pocket, but the opening size and wind loads exceeded the constraints of the current system.  As many architects are looking for options to make windows larger, the decision was made to replace the current aluminium vertical members, the mullions, with a stiffer option. The new design also incorporated the ability to strengthen it further. This new addition to the G.James range is used extensively throughout the Gasworks project.

Practically Completed

Practical completion was achieved on the 3rd August, 2013, however there are still minor works, interior fit outs and landscape work under way.  Building E has been designed so a residential tower can be constructed above it in the future.

The Gasworks project is an aesthetic feast, and well worth a look if you are in the area. Please consult the interactive map project to get the location and a summary of the project information.

IGUs. A sound acoustic solution?

sound and noise acoustic control with IGUsInsulating Glass Units (IGUs) or double glazing, have been a popular solution to control noise, but they aren’t the only, or even the best solution in many cases. The aim of this article is to explain how acoustic problems are identified, assessed and provide solutions to properly address them.

Acoustics

The acoustic performance of façades is becoming more important in building design, and not surprisingly is included as part of the Green Star rating process. Although it is a small part, it’s raising the profile of sound reduction and the need to find better solutions to the increasingly worsening noise problems in today’s society.

To better understand how to mitigate sound, it is beneficial to have an awareness of a few key ideas; how sound is transferred, the way different noises are measured, know about the principles to minimise the variety of sources and coordinating appropriate solutions. Prior knowledge makes finding a solution a lot quicker and easier when you are consulting a professional.  Using advice to compare test results, it is imperative to know the difference between glass only and window system results if you want sound acoustic solutions.

Determining sound factors

Noise sources in the vicinity of a project need to be identified to best determine the most efficient glazing solutions. Look for risk sources, some examples of which are below;

  • Traffic noise from vehicles – cars and/or trucks
  • Trains
  • Planes and flight paths
  • Trams
  • Boats
  • Entertainment venues
  • Industry – a warehouse, factory plant, a truck depot up the road

For each source, be aware of the proximity and direction it will be coming from.  Future changes that will affect sound transfer must also be considered – empty or older blocks that will be used for building development, planned roads and motorways to be constructed, or a feature that may be removed to expose the project to heightened noise distribution. This information will be assessed by an acoustic engineer or glazing contractor looking at the requirements of the project.

The two main properties that contribute to disturbance from noise are the frequency and intensity level at various frequencies, or volume. Both influence the selection of appropriate glazing systems for a project.

Frequency

Sound travels as sound waves (variations in pressure) that have different frequencies. When the sound wave hits an object, this will be absorbed, transferred or reflected dependant on the properties of the object and the frequency of the sound. Below is a table that describes the frequencies associated with different noises;

Frequency distribution

Volume

The inherent volume or loudness of noise is measured in decibels (dB). Following is a table that gives you an idea of how loud different noises are;

comparison of sound

 Acoustic fact:

The human ear cannot distinguish a change in noise level of 3dB or less.

Different types of glass will assist deadening the various frequency and sound levels. To decide what the best solutions are, the window systems need to be comparable.

Measuring how much a glazing system suppresses noise

The current standard unit that is used to nominate the amount of acoustic insulation achievable is the Rw. An Rw rating is applied to many products to compare its capability to reduce sound against similar products. However, the nature of glazing systems means that frequency plays a large part in the transference of sound. So correction factors are applied to the Rw and expressed as Rw(C, Ctr).

Using Rw Data results:

When looking at results, ensure you understand what the Rw rating applies to.  Glass only data will give you just that – a figure for the glass.  It will not be comparable with a whole of system framing. Glass only data has a higher figure, and misrepresents the effectiveness of the desired glazing solution.

Rw

The Rw, or weighted sound reduction index, is a material or system’s ability to reduce sound transferring through to the other side, of a window or wall. As a rough guide, an increase of 1Rw reduces the sound perceived on the other side by about 1dB.

Rw(C, Ctr)

The correction factor for the Rw takes frequency into account. Medium to high frequency noise like conversation, and faster traffic (travelling more than 80kmh) are nominated as the C number. Low to medium frequency sound like urban traffic and planes flying overhead are the Ctr figure.
If a project has a requirement of Rw = 32(-1,-4), then the Rw = 32, the Rw+C = 31 and the Rw+Ctr = 28. The noise frequency distribution determines the correction factor figure to be used. If the predominant noise source affecting a project is traffic noise, being a low frequency problem, the Rw+Ctr figure is used. In this case, the figure to achieve is 28. If a window system is rated at Rw30(-2,-2), the Rw+Ctr = 28, therefore achieving the above requirement. The Rw number should always be used with correction factors.

Testing the Acoustic Performance of Glazing Systems

Testing is done by accredited organisations in an acoustic laboratory. The testing space consists of two rooms of known acoustic properties separated by a wall with a high sound insulation. The rooms are constructed of thick block work with the entire laboratory sitting on airbags to isolate it from ground vibration. An opening is made in the wall for the glazing system. One of the rooms is set up as a source room, and one is the receiving room. The difference in noise level measured between the rooms is used to calculate Rw, C and Ctr figures that are attributed to the system tested.

Acoustic Solutions

There are several acoustic principles that are applied to the design of glazing systems to obtain the best performance to guide you in choosing the optimal glazing products.

Glazing design

Keeping sound out is like keeping water out – any gaps provide a path by which the acoustic efficiency of a system is reduced. Even the smallest crevice or notch out of a system makes a difference. Glazing systems can be riddled with gaps – good systems minimise these as much as possible. Testing is the only way to know how any system will perform.

Product selection

Restricting sound penetration is only as good as the barrier’s weakest point. Opening or operable parts of a façade are the hardest places to control sound, but improvements in technology are minimising the issue. With changes in door design to allow for access according to AS 1428, it is good to be aware these points are made weaker, acoustically.  With glazing developments, there are solutions to help minimise this issue.

Window systems with a positive closing force are more effective at blocking out sound. Awning windows and hinged doors generally perform better than sliding windows and doors.

Acoustic seals can be used to improve glazing performance and achieve a better Rw rating. The only way this can be accurately assessed and used for compliance, is if the glazing system is tested with the acoustic seals.

An air gap between the glass panels in a glazing system can provide a degree of sound reduction dependant on the size of the air gap. Typical IGUs with an 8, 10 or 12mm air gap, the improvement is marginal. Larger double glazed air gaps are much more effective, with 50mm being the “sweet spot” with only marginal improvement beyond this. These large air gap systems are generally the best performing of any glazing system.  Jockey sash systems can also be used to create large air gaps but have size restrictions and may cause internal condensation issues.

Laminated glass can provide equivalent or better performance than a standard air gap IGU. Typically the thicker the laminate, the better the acoustic performance. Specifically designed acoustic interlayers are now available that provide an increase in performance in standard interlayers

Looking for assistance with acoustic design

Window fabricators can help you understand the acoustic performance that their products provide. If you are aware of the nature of noise pollution in the vicinity of your project, then it’s a matter of matching the correct products to minimise this problem. Look for new technology becoming available to better deal with the increasing noise issues in today’s society.

When using window acoustic data, ensure you are discussing whole of window system data. There is a lot of glass only data available, but it’s the frame that is typically the weakest acoustic point of a glazing system. The glass only data will not give you a proper representation of noise control.

5 Points to Remember

  1. Understanding Rw(C,Ctr).
  2. Gaps in Systems = sound transfer. Minimise these weak points, especially in operable glazing.
  3. Larger air gaps in between glazing layers helps acoustically.
  4. Familiarity with latest technology in sound reducing products like acoustic seals and interlayers.
  5. Test results need to be comparable. Look at whole glazing systems, not glass only test results.

Helpful Links

For further information on the subject, please refer to the suggested following resources:

Generic and Custom Plastic Extrusions, Gaskets and Seals

PVC extruded plastic gasketThe G.James Glass and Aluminium Plastics department has been operating since 1995, and started out manufacturing just 2 products for in house use. Type and quantity of manufacturing has been growing steadily ever since. Commercial sale of products initiated 5 years ago, and now supports several industries.

G.James Extrusions

The industries that G.James manufactures PVC plastic extrusion for include – building and construction, automotive, commercial refrigeration, marine, shop front, internal fit outs and railways to name a few. They come in a range of colours and PVC types, from rigid, semi rigid and flexible, including nitrile or rubber modified and TPV (Thermo Plastic Vulcanite) or Santoprene equivalent (this has the same properties, characteristics and function, but without the Santoprene brand name) as well as Santoprene, if its specifically required. Co extrusions (extrusions made from two different materials) and bushfire (BAL) rated extruded gaskets are also available.

The G.James facilities are capable of large scale commercial production. The production lines can produce up to approximately 2000m of plastic extrusion an hour – depending on the size and shape of the profile. Products are designed up to 100mm in Circumscribing Circle Diameter (CCD). At peak times, it will use up to 40 ton of material a month – and that’s not at full capacity.

Extrusion design

After initial contact, the design process involves an in depth look at what is required – the use, appropriate material for the conditions – sun and weathering, heat and chemical exposure. Identifying potential issues and mitigating them, or troubleshooting issues that may have occurred previously. Assessing die design and making a more effective proposal are all looked at prior to signing off drawings for a die to be made. Die trials are run and the resulting profile measured up for quality assurance purposes before commercial runs begin.

This process can take up to a couple of months if there is a lot of design involved, but is usually less. Ordering plastic extrusion has a two week lead time, but standard runs or more urgent requests can be processed to cater to customer needs.

Quality

During the design process

Efforts are made to ensure the die design is as beneficial and cost effective to the customer as possible. For example, a recent job started out with a profile design from a customer that required considerably expensive tooling and production costs.  Working with the customer and making a few die modifications, these costs were brought down by 60% . No impact was had on the effectiveness of the extrusion.

As an initial saving, G.James can arrange to have the tooling price amortised into the production price per metre to offset the lump sum.

Use in situ

18 years of experience by the PVC extrusion manager, Jason Clarke, ensures personal service from someone who knows how to make it work. Trouble shooting feeding problems, stopping gaskets from “popping” out of position, gasket “wave” problems and better shape design are among other issues that are addressed.

Point of manufacture

A length from every roll of extruded plastic is tested to ensure a quality product. Measurements are taken and information is recorded and stored so it can be tracked back to when and how it was made. Materials that work into other G.James products are also trialled for a suitable fit on completion to ensure a whole of system customer service.

Back end quality control

G.James conduct investigations into existing scenarios that are having problems. Extrusion and glass checks, incorrect use and out dated design issues can be looked at to assess the cause of any issues. Advice is given on the findings, whether it is a change in plastics die design, or other members that are found to be out of tolerance.

Manufacturing Process

It’s a short but interesting manufacturing process. The material comes in pellet form that is control fed through a hopper into a spiralling screw or ram. The pellets are heated, mixed and compressed as they are fed through the spiralling screw, and finally forced through the die into its final shape. After the gasket is extruded, it is immediately cooled in chilled water, and then dried before being cut into designated lengths and boxed, or rolled onto a spool.

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Recycling

All off cuts of plastic extrusion are recycled on site. They are shredded and prepared to go through the same hopper feed and production process. As a quality control issue, recycled material is only used on non-structural gaskets, such as fly screen splines.

Brisbane designed and made, supply is distributed Australia wide, with much of our standard range available off the shelf at any G.James branch. For more information on product and supply, call the PVC manager, Jason Clarke, on 0403 352 703 or 07 3815 4908. Keep up to date by looking up the PVC page on the G.James website.

Thermal stress glass breakage

AGGAThe following fact sheet has been prepared by the Australian Glass and Glazing Association Technical Sub Committee and has been reproduced with the kind permission of the AGGA.

The original technical fact sheet is available as a downloadable PDF file.

Thermal Broken Glass

Introduction

Thermal stress occurs in glass when there is a temperature variance in different parts of the glass. If the stress caused by the temperature difference is greater than the strength of the glass, thermal stress glass breakage will result.
Thermal stress glass breakage is not a new phenomenon and it has been relatively well understood in commercial glazing for many years. However, given the increasing use of high performance, energy efficient glazing and the fact that some of these products can carry a greater risk of thermal stress, it is important that everyone involved in the glazing industry has a better understanding of thermal stress, its cause and how to prevent it.
As thermal stress breakage is not often due to a glass fault, but rather the result of a set of conditions that a pane of glass is exposed to, it is generally not covered by a glass supplier’s warranty.

Identifying thermal stress glass breakage

A glass fracture can be identified as a thermal stress breakage if the start of the crack is at 900 to both the edge of the glass AND the face of the glass. Depending on the magnitude of the stresses involved, the crack may only travel for a few millimetres before branching out or veering off-line, so the 90° angle of the initial fracture may not always be immediately apparent.
Breakages caused by thermal stress can be characterised as either low stress breakages or high stress breakages. Low stress breakage is characterised by a single crack that “lazily” makes its way across the glass, while high stress breakage is identifiable by the initial crack branching off into a number of separate fissures a short distance from its origin.

What causes thermal stress?

As mentioned previously, thermal stress is caused by varying temperatures in different parts of a glass pane. Absorption of the sun’s energy is one of the main causes of this temperature difference. The section of glass exposed to the sun absorbs the sun’s energy and, as a result, heats up. Any part of the glass which is shaded from the sun, for example, by the window frame, stays relatively cool.
The hot glass expands while the smaller, cooler area doesn’t. If the cool area of the glass isn’t strong enough to withstand the forces imposed by the expanding hot section of the glass, thermal stress breakage will occur. Putting the forces required to induce thermal stress into perspective, Pilkington estimate that for every degree in temperature difference between the edge of the glass and the centre of the glass, around 0.62 MPa of stress is introduced into the glass. Given that in some cases temperature differences of 20 to 30°C can occur, that equates to around 12 to 19 MPa. This is higher than the design stress used for wind loading!

Thermal stress risk factors

Given that thermal stress is caused by differences in temperature in a piece of glass and that breakage occurs when the ability of the glass to withstand this stress is exceeded, any situation or factor that increases this temperature difference, or decreases the glass’s strength, increases the risk of the thermal stress breakage.
Factors that can affect the risk of thermal stress include:

Edge Condition

Damage to glass edges during manufacture or installation is arguably the largest cause of low stress thermal breakage.
As US glass manufacturer PPG puts it: “The as-cut quality of glass edges is the single most important factor affecting the edge strength of glass. Poor cut-edges quality can reduce the glass strength by 50% or more…” “Glass edge quality and the resulting glass edge strength is particularly critical to the performance of the glass under the thermal loading …” Glass Edge FeatherThe level of thermal stress that a piece of glass can withstand is directly affected by the condition of the glass edges. The edges that are most resistant to thermal stress breakage are good quality clean-cut edges with no shells, vents or shark teeth. This may be difficult to achieve in laminated glass and edgework may be required to smooth the edges.

Glass Type

Different glass products have a different tolerance to thermal stress. Generally, the more solar energy a glass product absorbs, the higher the risk of thermal stress breakage. All glass manufacturers provide data on the solar energy absorption properties for their products.
Solar absorption can vary greatly, even between similar products. The use of a reflective coating can significantly increase the amount of solar absorption. This is because, in effect, the glass is absorbing the solar energy both on the way into the glass and then again on the way out after it hits the reflective coating.

Example:

Uncoated 6mm grey glass has a solar absorption rate of around 45%, while the addition of a reflective coating to this product increases solar absorption to 63%.
The use of transparent Low E coatings can also increase the solar absorption rate of glass. Low E coatings are designed to reduce the passage of radiant heat flow through the glass to improve energy efficiency. This leads to higher glass temperatures and increases the risk of thermal stress.
Another significant risk factor is the addition of heat absorbing films or any partial covering of a glass pane by other products (such as signs or paint) after installation. Both of these can increase the risk of thermal stress.

Glass Size

The larger a pane of glass, the greater the area of glass that is absorbing the sun’s energy, compared to its relatively narrow cooler edges. The larger area of hot glass results in higher levels of thermal stress in the edges of the glass.

Exterior Shading

Whilst glass properties are well documented and can be taken into account during the design phase of a project, accounting for exterior shading can be more problematic.
The effect that an external shading device has on thermal stress depends on a combination of its size, shape and location on the glass. Exterior shading is further complicated by its seasonal nature; as the sun’s position changes throughout the year so too does the shadows it casts.
In general:

  • Shading that covers 50% or less of the glass is more unfavourable than a device that shades a greater percentage of the glass;
  • Static shading is more unfavourable than mobile shading;
  • V or L shaped shading induces higher thermal stress, particularly if the point of the V falls on an edge of the glass.

Interior Shading

A thermal stress risk factor that is encountered more often in residential construction than commercial, is the use of curtains and blinds on the inside of a window. The impact that blinds and curtains have on thermal stress depends on the colour, type and other factors, however the effect can be significant.
While close fitting blinds or curtains help to minimise heat transmission into or out of the building, they can significantly add to the risk of thermal stress. To minimise this, the space between the glass and shade must be at least 50mm (preferably 150mm) and should be vented. Ventilation is provided by leaving a gap between the blinds and the walls, or frame, of 50mm at the head and 25mm at the sill.
The effect that blinds and curtains have on thermal stress is also dependent upon how much energy they reflect back onto the glass. Light colours are good reflectors while dark colours are not. Closed weave fabric helps trap heat more effectively while open weave lets the heat pass through. Venetian blinds are excellent heat reflectors as are metallised blinds.

Heating & Cooling

Artificial heating and/or cooling devices should be positioned so that they do not blow hot or cool air directly onto the glass surface, nor into the space between the glass and the curtains. Doing so may result in varying temperatures on the glass surface and therefore increase the risk of thermal stress.

Glazing Method

Commonly used glazing methods do not significantly affect the risk of thermal stress. The exception to this is structural glazing, which reduces the levels of thermal stress by reducing the temperature difference between the glazed edge and the centre of the glass. Care should be taken when using any glazing method that either encourages the transfer of heat away from the glass or covers unusually large amounts of the edges of the glass.

Managing the risk of thermal stress

The risk of thermal stress breakage can be eliminated by managing the factors outlined above or by heat strengthening the glass.
Heat strengthening increases the strength of the glass, which allows it to resist the thermally induced stress. Heat strengthening can be relatively expensive, particularly if required for laminated glass, so unless replacing glass, which has been broken under thermal, stress, a method of quantifying the risk level is needed.
Many glass manufacturers’ websites provide detailed information on thermal stress breakage. Some also provide online tools that enable you to perform a thermal stress analysis yourself, or they will perform a thermal stress analysis for you providing you purchase glass from them.
By using available information, the glass installer can objectively assess the risks prior to installation. In some cases redesign may be possible, eliminating the need for heat strengthening and therefore saving unnecessary expense.

Capitol Apartments

The Capitol ApartmentsCapitol Apartments has been recently constructed at 35 Peel St, South Bank, Brisbane, QLD. It is a 10 storey building designed by Kowalski and built by TMF. This project is situated in the busy west side of South Bank, along some major traffic routes – one being Queensland Rail train tracks and rail bridge.  It is an ambitious project considering its location, and had very stringent guidelines to achieve before it was allowed to be constructed.

Strict Design Criteria

The main aspect of design took into account the proximity to the adjacent train line. Acoustics is an obvious problem, but the location of the railway tracks are within a stones throw, literally. As such, protection of the railway tracks from litter being thrown onto the lines is of critical importance. Accompanying this, the architects designed a building with many differing glazing requirements to achieve a cohesive up market residential property. This building is to be used as furnished apartments for long or short term accommodation for people in the South Bank area. With venues like Rydges and other large hotel names in the vicinity, a boutique, stylish result needed to be achieved. The Capitol Apartments The initial design phase required the windows to comply with acoustic standards, or the apartment would not get approval to be built. G.James were the only glaziers that could beat all the ratings required, and provide evidence via testing that these results were guaranteed. The design initially specified opening sizes to be built to, but to ensure quality, it was actually done as a measure and fit job. As such, the lead times were brought down dramatically in the manufacture and installation scheduling required to meet the builders time line, which G.James achieved.

Design Resolution

To accommodate the requirements to protect the tracks from litter, all windows to the railways (northern) elevation were fitted with fixed Crimsafe screens. The balconies are set up as an Alfresco area, and the Lismore designed version of the 445 sliding door system was used for the operable windows overlooking the tracks and the city, with a fixed light beneath. The Lismore design, allows the sliding door to be operated from the inside, allowing the Crimsafe screen to be fitted and fixed externally. This alfresco area also helps protect the interior from noise pollution. The Capitol Apartments Bedrooms were fitted with jockey sashes to provide an adequate acoustic barrier, and living spaces had IGUs (as well as the alfresco area) to protect it from railway traffic noise. Both use the 451 system. Some balconies also have 136 Double Hung IGUs incorporated into their design. Other areas use differing glazing suites including the 165 slider vents to wet areas, 265 awning windows, 651 shop front with IGUs in the gym on level 1 with a 476 hinged door.  The main entry was a 475 auto sliding door, and the 477-300 bi-fold system with a lowlight under in  650 framing are a suitable finish in the restaurant. All framing not done on the railway elevation used various types of SGUs to suit the look required. The Capitol Apartments We have released a project map to provide the location and a summary of works.  Keep an eye out for the Capitol Apartments on this map…

Interactive Map: Building Brisbane

Brisbane construction projects by G.James Glass & Aluminium

Brisbane, being the location of our Head Office, sees many fine examples of G.James workmanship.   Here, we outline some of the biggest and best projects undertaken to showcase our capabilities in recent times.

The interactive map is designed so you can take a tour of some of our most recent and notable works.  Either at your desk looking out a CBD window, taking a stroll around town, and driving past a building or through an area you have always wanted to know more about.

Brisbane

G.James has contributed widely to what Brisbane looks like today.   There are buildings that have added to Brisbane’s sky line and to the diversity of looks and uses that are designed for the various parts of this fair city.  On some buildings, there are unique features that make them distinctive.  For example –

  • the ribbons of M&A,
  • the splash of red across the Australian Federal Police building,
  • the glass wall of Sir Samuel Griffith Centre,
  • the towering Aurora and Riparian plaza.

There are many buildings that have achieved the coveted green star energy efficient design,  some interesting artwork on glass designed by local artists – its worth a visit to the Anthropology Museum at UQ to see the ceramic printed window alone. Some of the buildings have specialised glass systems to suit the works being done, like the Translational Research Institute and the ABC headquarters.

There are projects that have altered the face of a tired old façade, so if you look at an old image of QIMR, you won’t recognize it.  And then theres the Suncorp Stadium which gives you a glimpse inside a place where state pride and competition is on the line.

The Interactive Map

The map is aimed to give you a glimpse into the depth the G.James knowledge base and provide an overview of the types of works that G.James is capable of.  It highlights projects done by various departments in the company, including:

  • Commercial departments
  • Residential departments
  • Gossi park and street furniture
  • Glass department

You can have a look at the map and plan out a scenic drive, or target specific jobs, or just get an idea of what we have produced, in your area.  As you can imagine, there are too many jobs to make this an all-inclusive list, but we aimed to include a range of jobs reflecting different styles and features.

A brief dossier on the project is included – a photo of what to look for, basic job data and links to further information on the project.  G.James can help you with any further information required for the jobs represented.

Explore Here…

Enjoy the exploration, and keep an eye on this space. Other areas will be released as our database of projects rolls out – Sydney, Melbourne, the Gold Coast, as well as other areas to be where you can find G.James fingerprints…

Until then, enjoy this insight into the River City.

Key:

 G.James Projects

 Gossi Designs

51 Alfred St – Efficiency in commercial design

51 Alfred St A green star accredited office block constructed in one of Brisbane’s growing commercial areas, 51 Alfred St comprises of a ground floor retail space with 8 levels of office space above.

51 Alfred St, Fortitude valley was constructed by Blackwatch Projects, to the design of Willis Greenhalgh Architects. The sustainable design intended to minimise its carbon footprint was a urban friendly solution to council and the community. It includes a smart foyer, featuring floor to ceiling full height glazing on two street frontages, and superb views to the city above level 2.

G.James Role

Development of the project went from initial “design in principle” early drawings to installation of the finalised glazing products. The project had a short time frame, and lead times for manufacture and installation had to be carefully managed.

The building incorporates shopfront glazing from ground floor to level 1 that used the 850-500 and 650-500 series framing systems. Hinged doors are 475 or 476 series, with 445 series sliding doors (as on some upper levels, also). G.James picked up the cladding package for the ground floor columns, which was made and fitted by the G.James Joinery department. QuickAlly, G.James scaffolding division assisted with providing access to entry the shop front entry glazing.

Upper levels utilizes the 651-500 curtain wall suite. The design had to allow for the addition of randomly placed aluminium horizontal and vertical fins that use different shapes in keeping with the difference in direction. There are also composite cladding positioned irregularly across the southern face, and frames the edge of the eastern face.

All of the differences in cladding and sun shading incorporated into the curtain wall, made for a wide variety of specialist panels.  This required coordinating the transportation and installation of the panels to be highly organised. Careful design, preparation and on site works were given particular attention at the corner feature to achieve the seamless angled cladding and glazed finish that spans the full height of the buildings office area.

Glazing selection

IGU’s were used in the vision areas of the tower to combat city noise and provide sufficient thermal and solar efficiency to achieve the green star accreditation.

The spandrel area uses a colourlite backing on clear glass to achieve the opaque finish. Charcoal and White were used to keep in theme with the buildings monochromatic scheme that highlights the slash of copper that makes the corner feature stand out.

Installation

There was no tower crane available for this job, so all of the framing hoisted into the floors from a crane on the street below.  Including the “Spider Hulk”, the name of the lifting crane that positions the panels into place.

51 Alfred St

“Spider Hulk” is the name of the machine that lifts the panels into position on the building.

Early design intended the framing to be fixed into cast ins – a quick and minimal fixing method that utilizes the concrete structure to enclose and support the framing. Later changes, however, meant that the frame fixings were redesigned and engineered to be fitted with bolts into the concrete.

The ground floor was site glazed as the size of the glazing was so large. There was also a curtain wall panel that needed to be site glazed. This requires extra safety measures and some specialised techniques to carry out.

Blackwatch had a tight program which was run like clockwork. It enabled overall job satisfaction with the resulting installation of the work performed by G.James, and we look forward to working on further projects together.