Design Efficiency

Obviously if every conceivable aspect of a building’s design was highly efficient then that would be a good thing and eminently desirable. However, when the building design industry talks about efficiency, it almost exclusively means operational efficiency: a measure of a building’s ability to provide functionality, comfort and amenity whilst minimising energy use and other forms of environmental impact.

Some projects may consider the initial embodied energy of building materials and the construction processes involved, but any detailed analysis of their full life cycle or even their ability to be readily recycled and re-used is typically of only minor concern. This is almost entirely a result of having no reliable information on what happens to materials before and after the building is built - and what happens to all the resources buildings need before they’re piped in and after they’re piped out.

The result is that the majority of concern focuses on the efficient use of energy during the operational life of the building. Energy use is currently quite topical, it is something that designers can relatively easily quantify and exert some control over. It is also what most government regulations and building energy codes focus on.

What’s Wrong with Operational Efficiency?

It is obviously desirable not to unnecessarily waste operational energy, especially given the long life expectancy of many buildings and uncertainties within energy markets. However, due to our lack of knowledge about cradle-to-grave life cycles, modern production techniques and embodied energy, we are unlikely to ever fully appreciate the true costs of achieving such high levels of efficiency.

  • Does it justify using high-energy materials, mined from increasingly fragile environments?

  • Do these materials have to be shipped from far away, with the complex transport infrastructures and energy that requires?

  • Do their fixing techniques mean lots of mastics, plastics and other products whose life-span and non-biodegradable/toxic ingredients we’re not entirely sure of?

  • Will future generations really be in a position to smash up our buildings and cart most of their materials away to landfill like we do?

  • Could we have designed them slightly differently to be readily disassembled with individual materials and components more easily separated?

  • When viewed from the future, might this have been a more effective and sustainable use of our design time and effort?

Thus, the real questions we should be asking become:

  • Are high-tech, highly efficient buildings actually sustainable?

  • Are there better ways to achieve more sustainable efficiencies?

  • Are we really looking in the right place for them?

Unfortunately there are no real answers to these questions – we simply don’t yet have enough solid data for all the locations we build in. But that doesn’t mean we can ignore them.

Natural Forms and Forces

This article was written to address one of the topics at the SmartGeometry2008 conference in Munich, during which the use of natural shapes and complexity as an inspiration for built form was a theme in many of the presentations. This is worth pursuing as it provides a very useful analogy.

Viewed as machines, plants and animals are not actually that efficient at processing and converting the food they eat into heat and energy. However, they have adapted to be highly efficient at collecting and using the most energy-rich resources available within their immediate surroundings.

Picture of a dung beetle.
Figure 1: Sorry, I couldn't resist a dung beetle picture.

Their lack of ‘operational efficiency’ is not really an issue as other organisms in their environment have adapted to be highly efficient at feeding off their waste. In fact, most ecosystems require these inefficiencies to sustain a complex and inter-dependent food chain. Even in death, plants and animals provide their entire resources back to the local environment in a useable form.

Of equal importance, the vast majority of plants and animals are surprisingly robust in that they can adapt their behaviour and use of local resources to cope with widely varying environmental conditions. The few that cannot have evolved in highly stable environments, but are extremely vulnerable if conditions do change – as we are now seeing with coral reefs.

Drawing Lessons

Drawing lessons from this, perhaps the simplest and most obvious design response is for us to adapt our buildings to capitalise as much as possible on everything the site and its local environment have to offer.

At the moment we don’t know enough about the wider impacts of extracting and removing resources from different parts of the country - let alone different parts of the world. We know that the materials and resources we are consuming are finite, but a complex global economy built on short-term profits and a cheap transport system allows us to ignore these concerns. Simply being able to afford to buy and ship something from half way round the world is no justification for actually doing so – the monetary price we pay to a handful of international companies in no way represents the true long-term economic, social and environmental cost of that transaction.

Rather than simply adding up numbers, we need to apply more common sense when choosing materials and resources. Even without detailed life cycle data, we all have a fairly reliable understanding of which materials require energy-intensive manufacturing, long-distance transport or rare minerals mined from far away and which don’t.

If we are serious about sustainability, then depending more on local resources means it is at least possible to constrain our impacts to the immediate environment. At this scale the effects are more obvious – use too much water and the dam will run dry. They can be more easily monitored – you and everyone you know can see the dam slowly drying up. And it is possible to take action – communities faced with significant local problems have been the mainstay of innovation and positive adaption throughout history.

Some will see this as a call for a more regionalist architecture, but it is really a call for the building industry to voluntarily take more responsibility for the ramifications of its actions and look beyond the simple dollar value of its materials and processes. It is also a call for us to re-evaluate where we look for design efficiencies.

A Better Approach

It is proposed here that most of the operational energy savings we are after don’t need high-tech solutions but can actually be found right there on site. Some examples we have worked on show that putting the building in the right place with the right shape and facing the right way can result in less than 40% of the energy use required by a building in the wrong place with the wrong shape and facing the wrong way. If you then consider the best location of windows, thermal mass and appropriate materials, the potential energy savings become an order of magnitude greater as it is so easy to get these aspects horribly wrong.

  • Right Place: Where on the site is the best position to make use of daylight, direct solar gains, cooling breezes, natural shading, geothermal energy or wind power? Is this even the best site for this building or does it need to be closer to transport and other amenities?

  • Right Shape: Is it possible to use parts of the building to protect other parts that need it, to build in shading, duct natural ventilation, reflect light or form thermal buffers? Is a tight multi-storey approach better than a sprawling single storey layout?

  • Right Orientation: What is the best direction to face windows for maximum solar collection, daylight availability or summer shading? What side should the trees be on? Which rooms need morning sun the most?

  • Right Aperture Ratio: What is the right glazing area to give adequate solar gain during the day but not radiate too much heat at night? Is more glass, less shading and a darker tint better than less glass, more shading and less tint?

  • Right Materials: Are lightweight or heavyweight materials most suitable? What about exposed thermal mass or super insulation? Will surfaces need constant cleaning or is rustic charm more appropriate?

It is important to note that pretty well all these criteria are usually resolved within the first few weeks of a design project. If you think about it, they represent the most important factors affecting the overall thermal and energy performance of a building. Yet with just a little extra design effort on decisions that you have to make anyway, huge long-term economies and efficiencies are possible.

To use another analogy, getting these things right isn’t just picking the low hanging fruit, this stuff is lying right there on the ground. Designers need to start foraging around a bit – looking a bit harder for the nice juicy bits and discarding those that are mushy and not-so-nice. Maybe we should also be a bit more experimental, looking under rocks and other unlikely places that may have been previously missed.


To translate this analogy, what we’re really talking about is a process of ‘optioneering’. This means generating, simulating and analysing a wide range of different design configurations to see how they stand up against a wide range of performance criteria, right from the beginning of each design. With many CAD and analysis tools now having their own scripting languages, creating design variations is something that is becoming much easier and more automatable. With tools like GenerativeComponents, maybe at some point ExplicitHistory and some of the parametric BIM tools available from the major CAD vendors it is becoming possible to generate and adjust even the most complex geometries and sophisticated layouts, representing an exciting new area of research in architectural and environmental design.

Also, with new building materials and constantly evolving occupancy patterns, the performance of many building types can be quite counter-intuitive. Thus, if the process can be automated, why not test a few configurations your instincts tell you could never possibly work. At worst you confirm your own understanding, at best you discover a potential solution you may never otherwise have looked at.

Is this Enough?

Patient on life support.
COR Building, Miami.

We are still designing the building equivalent of patients on life support. Our buildings need everything brought to them. They need constant feeding, cleaning and bathing. They are kept alive only by constant connection to electricity and fossil fuel drips. For them to remain useful and relevant, we need continuous cycles of refurbishment and renovation until the costs become way too high and we end up demolishing them.

It must be possible to design buildings that can actually do a few things for themselves. Why can’t they self clean to some extent, or even grow food, generate heat and energy, provide natural habitat and actually increase public amenity. Some buildings do manage some of these, but we need to go further. Integrated renewable energy systems are important as long as they are sufficient, easy to maintain and not just token applique. Green roofs and sky gardens are fine, but they simply replace something the building originally took away.

What is being suggested here are positive impacts rather than just minimal impacts.

One Last Analogy

Consider the Land Rover as a motor vehicle. No-one in their right mind would call them in any way operationally efficient, but they are astoundingly robust. Intentionally over-engineered, they can take extremely rough treatment yet can be worked on with the most basic of toolsets – for example most of the bodywork can be entirely removed with a single spanner and the engine completely disassembled with just a few of different sizes and a screwdriver. As a result they are used by utilities, mining companies, search and rescue, farmers, armies and even fire stations throughout the world.

The author's 1969 Land Rover Series IIa.
A Lexus RX Hybrid utility vehicle.

Apart from some major accidents, there aren’t many Land Rovers in the world’s landfill sites. Their ease of disassembly and the retention of almost exactly the same design over many years means that even wrecked one’s can be readily re-used as replacement parts. The example pictured on the right is a 1969 Series IIa - it is as much of an asset and provides as much utility to it’s owners today as it did nearly 40 years ago. In fact, it is claimed that 80% of all Land Rover Defenders ever produced are still in service (BBC News).

Thus, despite their relatively low operational efficiencies, it can be justifiably argued that they are a very effective use of the energy and resources required to make them. Will we be able to say the same of today’s high-tech, highly efficient hybrid vehicles in 40 years time ? Realistically, how many are likely to be still on the road then?


This article is not an argument against operational efficiency. However, I get the distinct feeling that in pursuit of high-tech and highly efficient solutions, we end up with the exact opposite of robust, easily maintained, highly adaptable and re-useable buildings. Instead we get them full of very expensive, bespoke and finicky detailing; difficult to clean and maintain yet quick to discolour and show signs of aging; sealed up with mastics, plastics and other short-lived materials that need constant attention; working well for a while but unable to accommodate any significant change of use without major refurbishment; everything welded and concreted together making destructive demolition the only recycling option; in short, a building stock that will quickly end up in the future as more a liability than an asset.

Instead of focussing so exclusively on operational efficiency, we need to learn the real lessons of nature and look to improve how efficiently we:

  • Make best use of local and renewable resources.

  • Ensure our outputs and wastes are in a form useable by someone/something else in the local environment.

  • Make every part of the building easy to disassemble, recycle or re-use so it can give back what it originally took away.

More importantly we need to look carefully at the buildings we have inherited, understand their shortcomings and work out what could have been done better to make them more useful and effective to us. Then we need to apply all the lessons learnt to make sure that what we build now is as much of an asset to future generations as it is to us.

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