Design for a Solar Earth. No Bills from the Sun.
Irelands first solar energy conference. June 2002.

Brian T O Brien
Solearth Ecological Architecture

So 'Design for a solar earth' ? What a strange title,
Surely it cant be a solar earth, not this part here in Ireland, surely ?
Well let me look at what I mean by a solar earth, and then lets look at what it would be to design for it. The Earth, the '3rd planet', is located about 150 million km from the Sun and is completely in thrall to it. Earths existence and survival is dependent on the most minor fluctuation in the Sun's energy. Earth's position, it's energy, its cycles of day-night etc are determined by relationship to, and rotation around, the Sun.

So Earth is certainly solar and thermodynamic, but what else is it ? Well lets look at how life emerged on Earth. Forgive me a moment of if I go all holistic on you, but it is important, and provides a scientific, and perhaps poetic underpinning, to the 'WHY' of sustainable and solar design. I'm going to refer to the theories of Professor James Lovelock. It might also be important if it helps me to convince my fellow architects tune in more to this subject. My hope is that I will be able to instantly find them a 20% hike in their budget (though not their fee). That's 20% more architectural fun, 20% less agonising. For engineers, I hope to convince you that the future involves 'less plant, more planting', 'less technology, more technique'. I'm sure you already know this but let's take a look anyway.

Earth is about 4 billion years old. After the big bang, or whatever of the many theories we attribute its creation to, it emerged as a hydrogen and carbon-dioxide filled bubble-, and a pretty inhospitable one at that, and remained like so for almost a billion years or so. When it eventually solidified life, in the form of bacteria, emerged and remained the only lifeform for a billion years. Over the next billion the gases and other elements were slowly created, allowing the conditions for algae, plants and oceans, and eventually animal life, to emerge. Over these billions of years the planet continued to support conditions for, at first a few and then increasing, numbers of lifeforms. These conditions were delicate, like Goldilock's porridge -they had to be 'not too hot, not too cold', but also not too acidic, not too saline, not too humid, nor composed of too many toxic gases. The astonishing thing is that the planet continued to support life, progressively becoming more not less evolved, despite the fact that in that time the Sun's energy ,ie heat output, increased to a huge extent. Earth was actually being bombarded by more and more solar heat, 25% more in total, so far. This is a massive increase in light and heat when you remember that as little as 4% increase is enough to begin massive climate change; ice caps melting etc, seasonal fluctuations biome creep etc. It's clear that any life form should have been frazzled back to its basic constituent parts, certainly not evolving to a higher form.

So why didnt it, why doesnt it ? Lovelock's theory, and one that is highly regarded now, is that the various elements of the planet; oceans, forests, rivers, insect colonies, earthquakes, rainfall, coral reefs etc seem to worked together to balance out these changes in solar radiation and maintain the conditions to keep all life forms thriving. Up till recently that is anyway.

So based on this we can see that Earth must be a complex system with very many parts, all working together to maintain the system, to maintain comfort conditions. Every element, every process supports the system and the system supports every part.
It is 'solar' ie it uses the Suns energy to power itself. It is 'cyclic' being formed of materials, water ,air that can only be cycled from one form and place to another, (ie a closed system materially).
and its 'safe' ie benign, where no artificial, synthetic or toxic compounds are necessary.
(this particular phraseology is courtesy of Edwin Datschefski of www.biothinking.com).

So no question; its a 'complex system'- but also simple, I mean remember how much trouble it is to even imagine it differently; to fight it: As William MacDonagh says Look at 'not doing it' as a design problem. Could you set someone in your office the brief to design a 'place' where the water is too dirty to let children play in, where the rain is too acidic to drink, the air so full of carbon that the 'place' heats up uncontrollably. A 'place' where you need to burn million year old precious hydrocarbons (emitting toxic gases, rubber particles, etc) to get to the shops for a pint of milk or to school, a place where buildings make you sick and, hospitals make you sicker.
Could you do it ? Well we do, and at enormous expense.

What about another design brief? Can you design a place which creates more clean air then it consumes, where its own materials increase in quality with no effort or forced energy, where free solar radiation is absorbed by surfaces and turned into nutrients, to create comfort and maintain this 'place'. A place where carbon-dioxide is neutralised, air and water cleaned by simply flowing within it, and where people learn just from being there.

Well, which project would you like to get an A in ? Clearly this latter is a very complex place, by the way, its the brief for a forest. It could easily be the brief for an advanced mixed use urban building.

So the question is can we design all our buildings, our cities, to operate with as much humility and elegance as this, to play a role in the system, the way the hydrological cycle, the coral reefs, the polar ice caps, do ?. Could we have our buildings and cities be tuned and integrated into this system to support it as a massive system, rather than undermine it.
How would we do it, how to inhabit and create our buildings, cities, societies so that they work with this system ? Well we must learn the operating rules.

We said that Earth was solar, a spontaneous thermo-dynamic, cyclic system; a 'living' system.
Living systems draw energy in from outside themselves, that is they run spontaneously on ambient energy. They use the flow of energy through them to maintain their physical structure (imagine a whirlpool as a diagram of this or remember how quickly the physicality of a tree or flower ceases immediately its energy source- light- or its ability to convert that energy, is interfered with). Form Follows Flow'. is the design maxim. Also though, their materials are drawn from the natural material cycle, ie. they are inert, safe, and ultimately cause no harm to the environment.
I wont deal much with materials here but it is integral to solar design. Living Systems are also intelligent; -responsive, capable of regeneration, feedback and evolution. Are our buildings ?

How do we do it, how do we integrate into this, well its a design approach. Its name is 'bio-mimicry'. We use Nature's energy and our ingenuity.

The way we, as architects and engineers, mimic nature is by being 'bio-climatic'.
That means we design to create comfortable conditions in a particular climate, using natural (biological) rather than mechanical means. Comfort creation and an understanding of the exact climate zone we are dealing with are vital to bio-climatic design, vital to mimicking nature in designing buildings.

The principal climate zones have different approaches to this bio-climatic comfort creation; In the Mediterranean zone, shading and some earth coupling is appropriate, In temperate maritime climates, like ours, passive solar (along with super insulation) works, in hot dry climates, shading and evaporative cooling is used, while in tropical climates, induced ventilation is the best approach. Natural cooling of different types can be used especially on bigger buildings in most climates.

So we need to make use of the ambient energy around us- sunlight, ground and water heat, the velocity of water, the flow of air. Remember in a living system all energy comes from the Sun, either directly or through its action on the Earths surface, causing winds, hydro action, biomass etc. All natural energy drives from the sun- its not so much not sustainability as SUNstainability (as Holocene's Joanne Tippett says). In fact the Earth receives enough solar radiation in 30 minutes to power society's activities for a year. Renewable energy is diffuse though- spread out in space and time, and of low quality in terms of meeting society's current expectations -not surprising when you realize that 'society' was built on the combustion of hydrocarbons rather than the production of carbohydrates as nature was.
In this climate then the appropriate bio-climatic approaches are familiar.
With small-scale buildings, the climate is the predominant challenge ('skin dominated' buildings as they are termed) so heating is the usual problem. With bigger, more densely populated buildings, (load dominated) cooling is the usual challenge. As you know a person in a commercial building can emit as much heat as a 100w incandescent light bulb. So many people working together emit the heat of quite a lot of light bulbs -though often far less light !

The design strategies to create comfort are actually quite straightforward; compact design for heating, passive solar heating and for cooling natural, or passive, ventilation with shading.

So lets look at these approaches in Europe and in Ireland. First, compact (centric and highly insulated) design. The idea is that since the skin of the building is the weak point (ie the surface represents stress; heat loss, wind chill, expansion and contraction, erosion etc all act on the skin) so the less of it to enclose a given area the better. It's all about surface to volume/area ratios and reducing them. The idea is to create strong (super insulated) envelopes and bringing the heat in around, rather than through, that envelope.

Looking at natural ventilation, there are many approaches. The simplest 'cross ventilation', requires careful thought; ratios of depth-to-height and opening-to-elevation, need to be considered. Another, 'stack affect' uses the fact that warm air rises: chimneys, atria, double skins.
The last the 'venturi affect' relies on the fact that air accelerates as it passes through a constriction; wind towers, aerofoils etc are used to induce accelerated airflow. Importantly
these approaches us ethe shape of the building, its form and fabric to meet the comfort objectives rather than fans and heaters. They give us an excuse to integrate sculpture, vertical elements, sails, canopies and towers etc into our designs. Remember I mentioned budget benefits ? its simply a re-allocation of resources from the 'kit' mentality of 'machinery and 'plant in achieving comfort', to the 'spatial' mentality of 'form and shape to achieve comfort'. This shifting of investment 'from the boiler house to the board-room' can reduce the M&E budget from 30% to maybe 10%, transferring it back to the building fabric-where its visible, and inviting M&E engineers to structure their fees based on building budget /performance rather than on 'kit'.

Before I look at 'passive solar' let me briefly skip to 'active' solar. Active solar is the use of technology to accelerate, and 'concentrate' the 'diffuse' solar radiation to the point where our modern lifestyles and demands, which are fairly concentrated, can be catered for. We use solar thermal technology to creating heat from the sun's rays to heat water or air. There are many examples of this and many have been explained in detail at this conference, indeed this, along with heat pumps, is technology that is making a real inroad here in Ireland. Or we create electricity using the Sun, one type of PV panel actually uses waste silicon from the computer industry sharing the benefits across to the material side of Einsteins equation. These PVs are suitable for integration into building facades, can act as visual and solar screens and are now approaching the price of marble cladding, clearly expensive but increasingly justifiable. In fact every structure and surface we spend so much money building as a society is a candidate for utilisation as a 'productive' surface in this way. The idea could be extended to a city or region scale. Look at the examples; motorways embankment overpasses in Switzerland clad in PVs, or those urban wind turbines near Amsterdam. Imagine all the south facing structures of Dublin, or Tralee, or all of our new national roads' embankments covered in energy production devices. And the same could hold true for water collection.

This could really be the way forward, particularly if you start to envisage a city or community of buildings as a network. That idea would be that instead of having a national grid, which is really a one way pipe, delivering energy only in most cases, we would have a national 'web', allowing energy be generated in many places, and consumed in many other places, the way the WWW allows information be transmitted from many sources to many destinations along a myriad different routes. No logjams, no power-cuts, resilient, flexible, like nature (a forest never gets a black out !). So a building fitted with wind turbines would be beside one fitted with bio-gas, and others with solar PV, each feeding the 'web' as the minute to minute weather shifts favoured their technology, each borrowing from the others when they were unfavoured by the weather.
The idea could be broadened to include heat webs, water supply and waste recycling webs.

What are the examples of these approaches? Well we know of solar collectors for water and air, building integrated photo-voltaics, solar chimneys, solar concentrators, solar urban infrastructures like these bus shelters in Europe, building integrated wind turbines such as this idea by Future Systems. There are many examples of building and city, working to concentrate ambient (diffuse) energy, using their own structures, each making many types of energy at the point of use, in short a city mimicking a forest or ecosystem.

So to the principle reason we are here perhaps: Designing solar buildings in Ireland, and similar climates. Well why bother, What's the point ? The sun never shines here anyway, right ?
I remember being on a study tour to Copenhagen a couple of years ago with a mission to convince some decision makers that Ireland needed a major demonstration building to show that advanced design-the kind we see in other countries, works in Ireland. We were in April, and had just visited a housing project which was heated by solar air panels. The heat was incredible in the collection room, so much so that at lunch -maps wer consulted to figure out how much further south Denmark must be than Ireland that it got such heat. Of course Denmark is further north than Ireland but we have an assumption that we don't receive as much energy as these other countries.

Actually Ireland gets 60% of the solar radiation levels of the equator. There is at least 2kWh of solar radiation falling on a msq of vertical south facing surface in Ireland per day, that's about 750 kWh per year on (each 1msq of) a similar elevation in the centre of Ireland, that's 25,000 kWh on the south façade of a two storey house (assuming the whole south façade is a collector).
If you could convert all of that to useable energy, it would give you enough energy for a well designed house (includes heating and electricity). However with current technology and budgets its difficult to get anything like even 50%. Theoretically though all needs could actually be met on a good site by reducing the demand, using the roof, using best available technology, reducing heat loss, and unwanted gains. Huge savings can be made.

So what are the rules of thumb? Well as with any problem, first question the question. Why passive solar heating ? why not design a building that needs no heating ? Two options, 'light and tight' like the Swedish one yesterday or, our favourite 'glass and mass': heavy insulation, high levels of thermal mass. It is theoretically possible and we know of many fine examples, though it leads to introverted design. Taking the other, more extroverted, approach; we first need to lessen the load, lower the stress on that envelope. Site planning is key. Earth coupling/earth sheltering is possible, tapping into the ground's ambient heat. Buildings should obviously be arranged along east west axes;-the long dimension of the building facing south. Totally south facing is optimum since for each 3 degrees off south, the heating done by the Sun drops by 1%.

At all times remember where the Sun and wind are in our location (bio-climatic).
Then we shelter the site, using landscape, berms, etc remembering the rule of sheltering; given a sheltering element, we build at a distance from it of between 5 and 12 times its height (ie between where the shade stops and the wind begins) if possible. Tactically we may have to sacrifice solar access to some areas (the ground floor, the east elevation etc) if in a dense or overshadowed site. At least we must be intentional and design for it.

So what about form ? Well clearly longer and narrower is optimum, with living spaces to the south, and service spaces to the north -a familiar enough rule of thumb. Throughout history there have been many variations on this theme; Curves, terraces, Palladian wings, earth sheltered building etc. There has also been some research into the impacts of solar shape, by people like Peter Bosselman and Ralph Knowles.
What about height ? Higher buildings are often better in solar (as well as in other) terms. The reason is that warm air and warm water rise,- the two ways to transport heat without using energy. The dormer bungalow (much beloved by the planners of Ireland) is not a solar system !
Two storey units ie. duplexes, houses etc are the ideal thermo-siphon-the most sustainable energetically of small building types. Even in urban apartments like is our own Daintree Building-hopefully Irelands greenest commercially funded building when completed next year- the rising warmth from the neighbour is useful. This passive heat flow affect can be taken advantage of for passive solar cooling also, eg. dual facades.

The next thing is to collect the heat: Conservatories, windows, trombe walls, solar panels, transparent insulation are used. All are solar collectors, some low tech some high tech, some with moving parts some with moving liquids. The principle difference is cost, yield etc. All need unobstructed access to light and all work on the 'greenhouse' affect; solar radiation in the form of light is short-wave and passes through glass, surfaces absorb and emit it as heat which is long-wave, and cannot easily pass through the glass layer as radiation again.

But common sense reminds us that windows lose heat too. The best window technology is still only a quarter as good as an average insulated wall. So how much glazing ?, where ?, when ? For residential design, 25% of the floor area of a building as window area is a good balance. Of that 60%, in houses only, should be on the south façade with the rest shared out among the others.
For commercial buildings openings can be shared more evenly among all elevations including, to some extent, the north one. This is due to different usage patterns and the fact that heat gain occurs from inside also.
There are some glaringly obvious considerations (the'no brainers' as the US calls them):
· I must not lose more heat in winter than I gain between spring and autumn.
· I must not put heaters in the conservatory (beware of those wanting an 'extra room' thing here) -its a net energy loser then.

There are two other techniques I believe could make for good design, that are hardly known. Transparent insulation material, or TIM is one. This consists of sheets of light coloured, lightweight cladding. Its transparent capillaries allow solar energy through as light, striking a building's surface and warming it. The air stored in the sheets capillaries then acts as insulation, stopping the heat escaping. Its elegant, clean, productive and suitable for 'white' architecture.

Trombe walls consist of glazing elements, usually as the cladding, in front of dark absorbing surface, usually the structure. The light gets through the glass and is absorbed, warming the structure, which then conditions the space. Since heat is given out to both the outside and inside though, its not as effective as TIM but, if viewed as simply a beneficial side affect of an esthetical decision-say to create a 'dark' architecture then its clearly beneficial.

Also, obviously we must remember that in commercial buildings cooling and lighting are the main demands, so the challenge is slightly different. Large windows for daylight seem attractive, but glare, excessive solar gain and winter heat loss can quickly outweigh the savings on artificial lighting. Computer modelling is necessary with bigger buildings, a consultant who is open to this type of thinking is even more necessary. We have to be the brain of the system.

So then the heat is collected, where does it go ? Well mostly into the walls as it happens: around 60% while the floor gets from 20-33% depending on its material. Clearly covering the glazing(Ireland is culturally prone to over-curtaining) or absorbing surface up wont help. In Ireland due to weather fluctuation only about the first 50mm of mass is used for absorbing the heat, before it begins to flow out again. Moving the heat around is a question. Low tech. systems rely on radiance, and some convection (hence the benefits of taller spaces). More elaborate systems can use closed loops working by thermosyphon or pump to do the same.

I haven't addressed all aspects of solar design; windows, heating systems , management systems are all complex elements that help make up a bio-climatic building and could take a lecture, or a consultant , in themselves.

What are the costs ? well anywhere from 5-10% extra (domestic building) for insulation, sunspaces, shutters, TIM etc. As little as 0-5% on bigger buildings can get you a long way.
The benefits ? firstly in money; 33%-50% savings on heating fuel (through passive solar design), reduction in CO2. Health and price security. Our clients constantly respond to these two benefits.
More importantly though, the creation of new spaces, lightness, indoor- outdoor relationships, and delight. The other design strategy (compact, super insulated buildings) can do as well in terms of energy, but lose on the whole delight/health side of the equation.

The Daintree building here for a 12% or so cost margin will create heat that costs only €75 a year per apartment. This building is heated with heat pumps, active solar and has multi storey, breathing wall construction, green roofs and many more sustainable features.

So how can we make architecture out of all this ? Remember we have two objectives; to make buildings that fit into the working process of the planet; solar cyclic and benign. Here in the Real Goods passive solar building in California (by Sim van Der Ryn) the vital task of holding the heat in at night, or designing how it is emitted, is executed elegantly with night shutters that drop down to be daylight reflectors. You can really see the meaning of the maxim 'passive buildings need active occupants' here when I tell you the original design found these too heavy to move manually. We must use night shutters, seasonal layers and screens to allow -the building adjust to and compensate for fluctuations in weather, heat, light, precipitation etc. ie to mimic nature

So what are the limititations to solar energy in buildings ? I suppose the most glaring one for me is that solar rights are legally undefended in most of the western world. There is no legislation covering solar access as an energy source. Imagine creating a building designed to power itself on solar energy, and someone comes along in a crowded city, and sticks a bigger building to the south of yours. They could do it in planning terms, if they met certain skylight criteria, or were deemed of national importance etc. but they would be effectively chopping your building down, strangling it. We need these rights established in law. Clearly there is a big issue with the cost of photo-voltaic panels here in Ireland. PVs are the easiest renewable electricity option in an urban environment. Other countries offer tax breaks and free hook up to the grid, we must have these. And on that there are real barriers to inter connection; the technical instability of the national grid here also. There are also imaginary barriers ; a perceived unwillingness by the grid to co-operate with small scale generators in allowing interconnection at a fair price.

Perhaps the biggest barrier though are in our minds. We insist on running cost benefit analyses on sustainable technologies the like of which we do not do with other elements of a building. How long does it take to pay back we are asked all the time ? Well its from 2 to 12 years for solar, but no one asks how long a kitchen or a roof takes to pay back. We must adopt an attitude that, like the inside toilet or universal accessability, this is just how it must be done now, this is evolution.

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SoleEarth Ecological Architecture
Solearth provides the highest calibre architectural design and contract administration services for residential, institutional and urban projects of all sizes, which include an environmental agenda.