Long life, loose fit, low impact: Playing the long game on sustainable buildings

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It may not be possible to re-love every component of a building but if we want ensure buildings remain as sustainable as possible throughout their lifetimes, the property industry needs to embrace the “three L’s”: long life, loose fit, low impact.


There’s no such thing as a perpetually sustainable building. Just as a computer becomes obsolete once you take it out of the box, so it becomes increasingly difficult to maintain a building’s sustainability once it opens. 

All buildings, no matter how well-intentioned and well-built, degrade over time, increasingly so with climate change. 

It may have carbon neutrality on the drawing board but staying that way becomes increasingly difficult once operations start. This is very apparent in commercial buildings where deterioration and maintenance present challenges, as do decreases in energy efficiencies. Moreover, wholly replacing interiors in these buildings, often less than a decade in, pose a repeated set of sustainability demands.

Tone Wheeler, Environa Studio

Only some parts of buildings are truly “sustainable” and only for a period of time. All buildings, no matter how well-intentioned and well-built, degrade over time, increasingly so with climate change. 

Rising costs of maintenance and repairs lead to buildings consuming more labour, materials and resources, and becoming less and less sustainable unless the environmental impacts are offset. Add to that the “virtual replacement” of a building as its interiors and services wear out and are renewed over time.  

In light of those issues it’s little wonder the idea of “re-loved” buildings has taken hold, reusing as much as possible while upgrading to modern standards. 

While it seems like a great idea, in reality it casts many shadows. To understand why, let’s divide non-residential buildings, namely commercial/office buildings, into three parts: the envelope/armature, the interiors, and the services. 

While each third is roughly equal in initial cost (labour and materials) and therefore environmental impact, they have varying ongoing issues and sustainability does not pertain equally to those three parts.

There are clear differences between each of those three parts in terms of longevity, when they need to be replaced, maintenance and repairs, and therefore how we design for those changes. When considering the desirability of retaining an existing building, we must first consider that what constitutes sustainability for these three parts.

The skeleton and skin of a building is easily recycled

The “envelope/armature” is the skeleton and skin of a building, the structural floors and walls, and the external enclosure. Traditionally, it lasts far longer than interiors and services. Throughout the 20th century these elements became increasing more durable, from steel and timber structures with brickwork and timber sash windows, to concrete frames with aluminium curtain wall glazing. 

Many older commercial buildings demonstrate that the envelopes/armatures can have a lifespan of over 100 years, increasingly so since pressurised “skins” were developed. Even the roofs are lasting; it’s worth noting that Australia has mostly avoided the flat roofs in Europe and the USA with bitumen finishes that need to be replaced frequently.

Where a building’s internals change to adapt to new uses and circumstances then often the externals radically change, with an increasing loss of sustainability.

Its durability means the envelope/armature is often recycled intact into the future, particularly where a continuing use is envisaged. This continuing use can help “offset” the high embedded energy and environmental considerations of structural materials such as steel, aluminium and concrete by amortising them over time. As we shall see more time is now being devoted to the environmental consequences of internal materials than those of the envelope/armature.

King George Tower, Sydney © Peter Miller

Where a building’s internals change to adapt to new uses and circumstances then often the externals radically change, with an increasing loss of sustainability. The degree to which buildings can change over time is beautifully documented in Stewart Brand’s book, How Buildings Learn

Brand, the principal author of the 1960s Whole Earth Catalog, considers the lifespan of urban buildings and the ways they adapt over time. Brand shows how buildings that start out with a particular purpose and scale can form the basis for larger or expanded buildings with different purposes, signage and form. What we learn from this study is that the city is more dynamic than many architects want: great buildings of one era can be “retained” in theory but are effectively demolished to cater to a new use.  

It’s a lesson that can be hard to accept. But here are two examples in Sydney. The original “King George Tower” (John Andrews, 1976) had external stainless “triagrid” structures with panels that provided shade (horizontal to north, vertical to the west) as well as access for the cleaning and maintenance of the windows. 

In a refurbishment 30 years later, the glazing was upgraded to provide sun-control, a conventional building maintenance unit was added and the stainless spidery frames removed. Much of the character disappeared, and along with it, the embedded energy of the sunshade structure. Hopefully the new higher performance façade lasts longer than the original.

Even more dramatic was the conversion of Sydney’s IBM office building (Stephenson and Turner, 1964) into apartments. Its elegant banded concrete/glazed walls with shading hoods turned into a lumpen flush block of dark-green paint, and little of the original external material was kept. Surmounted by an incongruous “golden temple” (Walter Barda, 2002), it stands beside the Harbour Bridge as an example of how not to recycle a great commercial building. 

It’s what’s inside that counts

The interiors are another component of an office building. They are often replaced as tenancies change, and in Australia, commercial tenancies are often very short, around eight to 10 years. When there’s a change in tenancy, there might be changes in floor finishes, wall partitions and doors, fit-out furniture and equipment.

It’s interiors where so much churn takes place and where much of the focus on sustainable materials has been concentrated.

This churn in internal fitout where the former tenant’s interiors, equipment and materials are thrown out and completely replaced for the new tenant is a serious sustainability challenge. Often it’s done outside of working hours – during “the midnight shift” where there’s little control over the way materials are demolished, put into trucks and disposed of at the tip. This is a major failure in the pursuit of perpetually sustainable buildings. 

A building may have sustainable accreditation when it’s built, say from Green Star or NABERS, but it’s the churn of the interiors that will render that grade misleading and make the building “unsustainable”. The move by the Green Building Council of Australia away from awarding Green Star for building design and towards both interiors and the buildings in use, with monitoring on an ongoing basis, is to be roundly applauded.

As indicated earlier, it’s interiors where so much churn takes place and where much of the focus on sustainable materials has been concentrated. The framework for consideration of these issues is set out in Cradle to Cradle by Michael Braungart and William McDonough. 

Cradle to Cradle, by Michael Braungart and William McDonough

One key indicator of the revised thinking in this book is the identification of “down-cycled” as opposed to recycled is considering the value of materials. The now growing “circular economy” puts an emphasis on retaining the highest value possible in materials rather than dumbing them down as is often the case with fit-out and joinery in commercial tenancies. 

Commercial floor coverings, notably carpet, came in for early consideration, because of their relatively short life-span, particularly in areas of high wear. Major suppliers of carpet tiles have introduced products where the floor tiles are totally made from recycled materials, low to non-outgassing, with programs offering to take back the carpet tiles and ensure that they are repurposed as carpet tiles again, recycled not down-cycled. 

There are now carpet tiles that are said to absorb some of the noxious atmosphere inside the building, a key issue in an office’s internal environment where new paints, furniture, fittings and equipment can all outgas volatile organic compounds (VOCs).

There’s also lifts and airconditioners to think about

Services are the third aspect to consider in sustainable commercial buildings. These are inevitably more complex than they in residential buildings, particularly the lifts, airconditioning and mechanical exhaust, electrical, controls and communications systems. It’s often obsolescence as well as failing maintenance that leads to an upgrade for these services. Nothing like failure of lifts or AC to ramp up the demand for replacements, placing stress on ongoing sustainability.

Services in commercial buildings have changed dramatically in the last 100 years. Lifts, invented by Elisha Graves Otis in 1851, have improved over time, including energy efficiencies and better automating controls in lift selection. Quicker and quieter, the desire is often to upgrade not just the car’s interior, which is subject to heavy use and abuse, but the entire system. In less than 25 years it’s desirable to remove and replace the lifts within the existing lift shafts.

Likewise, airconditioning, designed by Willis Carrier in the 1920s to dry tobacco in the USA, has improved radically. Except in the coldest of climates, it’s cooling that’s required inside commercial buildings because of the heat loads generated by the high density of occupants and equipment. This often leads to internal environments that are stuffy, circulating air with pollutants, germs and odours throughout the building, a key area of concern in building upgrades, where a wholly new approach to airconditioning may be introduced. 

Advances in the airconditioning equipment are three-fold: compressors have improved in both efficiency and noise control, with less reliance on water cooling and hence less problems with Legionnaires’ disease; improvements have been made in ductwork in design and insulation to reduce air drag, noise and air speed, and can deliver air more efficiently; and the temperature delivery can change from duct work to “chilled beam” technology.

The complete replacement of interiors and fit-outs could happen every 10 years with lifts, airconditioning, lights, power and communication systems being replaced every 20 years. 

This third improvement is a change in delivery approach to try to control the temperature of the building rather than the air, that is “building conditioning” rather than airconditioning. This is a recognition that radiant thermal comfort is a more dominant sensory perception by a human than convection and conduction combined, as shown by P.O. Fanger in his seminal 1970 book Thermal Comfort. We inherently know this from older buildings where the heavy thermal mass ensures that a constant temperature can be maintained over a long period, but these are often the very buildings that had large ducted airconditioning systems installed. 

Thermal Comfort, by P.O. Fanger

Changing these interiors from airconditioning to building conditioning by using “chilled beams” technology (which is really radiator-like panels that absorb heat), can be difficult and expensive in a retrofit, not to mention the loss of embedded energy in the AC ducting and equipment that is obsolete. 

The complete replacement of interiors and fit-outs (one-third) could happen every 10 years with lifts, airconditioning, lights, power and communication systems (another third) being replaced every 20 years, a fundamental issue in regard to ongoing sustainability. 

A new approach to buildings: Long life, loose fit, low impact

A new approach to repurposing buildings addresses these issues by more sensitively removing the interiors and services, by finding ways the materials can be recycled or down-cycled so that zero materials end up in landfill. The meme for this approach is the three “L’s”: long life, loose fit, low impact.

Long life means ensuring that the high energy-density materials required for the envelope/armature are built to last, say 100+ years. It is this part that we are predominantly re-loving when we recycle a building.

Re-loving a building is a great idea, but how much are we really reusing and how much are we replacing.

Loose fit is the approach we take to the interiors and services: if we know materials and equipment has a short useful lifespan we should plan for its replacement ahead of time, designed in such a way that installation and removal can be done in an orderly and non-invasive way. This way materials can be recycled rather than down-cycled, and so less damage is done to the long life part of the building. 

Everything should be screwed or bolted in place, not nailed and glued, so it can be unscrewed and unbolted – “use a spanner, not a hammer”. Services should definitely be loosely fitted in such a way that they can be removed and replaced when they become outdated or superseded. Ideally, they should be surface mounted so replacement can be done without doing major damage, or requiring invasive or unnecessary changes to the building as a whole.

Low impact is choosing materials that meet the highest green standards, from cradle to cradle; taking into account resource depletion, energy and labour in manufacturing, transport and installation, longevity in use, and possibilities for repair/reuse/recycling when the inevitable churn comes. Interior fitouts should be chosen from low impact materials: low outgassing and low environmental impact.

It’s often said that the building may be sustainable because it’s a hundred years old. However, the building has only been sustainable in its external envelope for that period of time, while the interiors and the services have gone through a number of cycles, quite often not monitored or considered and not part of an active sustainability program. 

Re-loving a building is a great idea, but how much are we really reusing (probably one third of structure and envelope) and how much are we replacing (probably two thirds of the interior and services). It’s reasonable to demand that once the armature of a building is constructed it will have a long life, independent of its changing uses internally, and that it can be environmentally amortized over a far longer time than the interior and services. 

We may not be able to re-love all of the building, but it’s crucial to re-love what we can, otherwise our buildings will be like 200-year-old axes that have three heads and four handles.

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