Sustainable & Ecological Architecture
There is lot of talk about Sustainability these days and rightly so. But what is it? How does it apply to Architecture? Is it relevant? To answer these questions we have to look at the current situation in relation to the built environment.
Construction and other related Architectural processes contribute greatly to this country’s greenhouse emissions, both during the construction process and the ongoing use / general maintenance of buildings / structures. In many cases the methods of construction and processes are put in place with a very low level of appropriate technical input.
Scant regard is given to what is commonly known as sustainable principles. There may be a large focus on the cost of the initial construction but little on the efficiency of various systems employed in the construction. By using sustainable principles one can reduce the direct need for artificial energy, vastly improve the quality of the built environment and save money, particularly if you are the direct contributor to the running costs of a building or structure.
However regardless of cost issues, application of sustainable principles in architecture greatly adds to the well-being of the occupants of a given building / structure. Well-being may be hard to define or pin down, yet its relevance encompasses many aspects of a building one occupies not often considered in detail in Ireland including day-lighting, ventilation thermal comfort and material specification.
Sustainable Architecture reacts and addresses climate, lifestyle, site characteristics. A list of considerations for a particular project may look something like this:
Sustainable & Ecological Design Considerations (Green Architecture)
- Location, Site & Flora characteristics
- Climate (Both macro & micro)
- Human requirements, budget & brief
- Expert input / Knowledge of materials & Regulations
- Available Local Materials & Construction experience. Specific Material specification.
There is much talk / debate about the so called “Green Radicals” / ‘Green Hippies” etc. being off their rocker! However all of this discussion and labelling of people is completely missing the real issue, which is in this context:
Sustainability = Sustainable Ecological Architecture = Common sense & Economic sense.
Thus there is no one big solution. One has to consider all the aspects of a given proposal before proceeding and consider fully one’s actions in this regard. As mentioned it is for instance not good enough to consider the cost of building as just the initial construction cost. The life cycle costs must be always factored in. And simple solutions are best.
Cummins + Voortman are one of the leading Architectural Practices in Ireland in terms of implementation of architectural sustainability and low energy design. For instance we have not used Oil or Gas as a fuel source on any of our new projects to date, while only two existing buildings continued to use gas, but only in a small way and the clients have the option to change this out in the future. (Robert Cummins Director has not utilised Oil or Gas as a fuel on any new project since 1999).
This commitment has not resulted in additional cost for clients during construction yet it has resulted in substantial on-going savings in the use of the buildings to date. The important way to progress the use of sustainability in Architecture is to do it by default in one’s work and not as an optional and often as a perceived expensive extra.
Sensible Application of Sustainability
Cummins + Voortman Ltd. strive to incorporate sustainable design principles into all work carried out. (Green Architecture) There is much focus on using sustainable principles to “save the world”. However there are many areas where sustainable principles are of great benefit economically to the individual who is for arguments sake building their own home, renovating their apartment, extending their farm buildings/yard etc. Below is an short non-exhaustive list of areas where use of sustainable principles and common sense can achieve dramatic results.
Construction and other related Architectural processes contribute greatly to this country’s greenhouse emissions, both during the construction process and the ongoing use/ general maintenance of buildings/structures. In many cases the methods of construction and processes are put in place with a very low level of appropriate technical input. Scant regard is given to what is commonly known as sustainable principles.
There may be a large focus on the cost of the initial construction but little on the efficiency of various systems employed in the construction. By using sustainable principles one can reduce the direct need for artificial energy, vastly improve the quality of the built environment and save money, particularly if you are the direct contributor to the running costs of a building or structure. However regardless of cost issues, application of sustainable principles in architecture greatly adds to the well-being of the occupants of a given building/structure.
Well-being may be hard to define or pin down, yet its relevance encompasses many aspects of a building one occupies not often considered in detail in Ireland including day-lighting, ventilation thermal comfort and material specification. Sustainable Architecture reacts and addresses climate, lifestyle, site characteristics. A list of considerations for a particular project may look something like this:
By careful use of appropriate insulation materials and detailing one can dramatically improve the comfort for occupants of an existing apartment or dwelling. How often do you here people in Ireland comment at home “God it is cold today!” or “is the heating on yet?” etc. The normal reaction to dealing with a cold house has been to install a new boiler or larger boiler. All across the country houses were converted to oil or gas and no thought was given to the provision of insulation. Therefore the house was never really comfortable or else it cost a lot to heat. Did you know that buildings could be insulated externally? No need to line the walls internally and avoid all the associated disruption. Obviously it comes with a cost but if it is carried out in conjunction with a new coloured render you avoid having to paint the dwelling externally in future years making a saving.
There are foil based insulation sheets that are as little as 12mm thick, yet provide as much heat retention as 170mm of conventional insulation. These can be used to line internally in a dwelling where appropriate and vastly improve comfort of the occupants yet do not reduce the space internally in a perceptible manner.
By use of alternative rainwater systems the need for and the costs associated with large rainwater run-off facilities or soakaways is avoided. Use of external paving that allows water to penetrate through and filter into the ground below can result in stunning results. This means a reduced need for clearing of blocked gullies and drains etc. More time to go for that walk or watch the latest football match on TV! Of course now rain harvesting is an option everyone should be looking at to reduce there dependance and use of the public water supply.
The Principles of Heat Transfer
General Principles of Heat Transfer and it’s relationship to Insulation. All thermal insulation materials work on a single basic principle: heat moves from warmer to colder areas. Therefore, on cold days, heat from inside a building seeks to get outside. And on warmer days, the heat from outside the building seeks to get inside. Insulation is the material which slows this process.
Phenolic, rigid urethane and extruded polystyrene insulation materials for instance have tiny pockets of trapped gas. These pockets resist the transfer of heat. They will not stop the loss or gain of heat completely. Buildings, no matter how well insulated will need a continual input of heat to maintain desired temperature levels. The input needed will be much smaller in a well insulated building than in an uninsulated one – but it will still be needed.
Heat Transfer Explained:
Before dealing with the principles of insulation it is necessary to have an understanding of the mechanism of heat transfer. When a hot surface is surrounded by an area that is colder, heat will be transferred and the process will continue until both are at the same temperature. The heat transfer takes place by one or more of three methods:- conduction, convection and radiation.
Conduction is the process by which heat flows by molecular transportation along or through a material or from one material to another. The material receiving the heat being in contact with that from which it receives it. Conduction takes place in solids, liquids and gases and from one to another. The rate at which conduction occurs varies considerably according to the substance and its state. In solids, metals are good conductors, gold, silver and copper being amongst the best.
The range continues downwards through minerals such as concrete and masonry, to wood, and then to the lowest conductors such as thermal insulating materials. Liquids are generally bad conductors but this is sometimes obscured by heat transfer taking place by convection. Gases (e.g. air) are even worse conductors than liquids but again they suffer from being prone to convection.
Convection occurs in liquids and gasses. For any solid to loose or gain heat by convention it must be in contact with the fluid. Convection can not occur in a vacuum. Convection results from a change in density in parts of the fluid, the density change being brought about by a change in temperature. The process of convection that takes place solely through density change is known as natural convection. Where the fluid displaced is accelerated by wind or artificial means the process is called forced convection. With forced convection the rate of heat transfer is increased – substantially so in many cases.
Convection In Gases
If a hot body is surrounded by cooler air, heat is conducted to the air in immediate contact with the body. This air then becomes less dense than the colder air further away. The warmer lighter air is thus displaced upwards and is replaced by colder heavier air which in turn receives heat and is similarly displaced. There is thus developed a continuous flow of air or convection around the hot body removing heat from it. This process is similar but reversed if warm air surrounds a colder body, the air becoming colder on transfer of the heat to the body, and the air becomes displaced downwards.
Convection In Liquids
Similar convection processes occur in liquids, though at a slower rate according to the viscosity of the liquid. It cannot be assumed however that convection in a liquid results in the colder component sinking and – the warmer rising. It depends on the liquid and the temperatures concerned. Water achieves its greatest density at approximately 4C. Hence in a column of water, initially at 4C, any part to which heat is applied will rise to the top, but, alternatively. if any part is cooled below 4C it too will rise to the top and the relatively warmer water sinks to the bottom. It is always the top of a pond or water in a storage vessel which freezes first.
Requirements Of An Insulant
In order to perform effectively as an insulant a material must restrict heat flow by any, and preferably, all three methods of heat transfer. Most insulants adequately reduce conduction and convection elements by the cellular structure of the material. The radiation component is reduced by absorption into the body of the insulant and is further reduced by the application of a bright foil outer facing to the product.
The process by which heat is emitted from a body and transmitted across space as energy is called radiation. Heat radiation is a form of wave energy in space similar to radio and light waves. Radiation does not require any intermediate medium such as air for its transfer, it can readily take place across a vacuum. All bodies emit radiant energy, the rate of emission is governed by:
•The temperature difference between radiating and receiving surfaces.
•The distance between the surfaces.
•The emissivity of the surfaces. Dull matt surfaces are good emitters/ receivers, bright reflective surfaces are poor.
The same applies to items of plant – pipes, vessels and tanks containing hot (or cold) fluids. If there is no heat input to compensate for the loss through the insulation the temperature of the fluid will fall. A well insulated vessel will maintain the heat of the contents for a longer period of time but it will never on its own. keep the temperature stable.
Thermal insulation does not generate heat, it is a common misconception that thermal insulation automatically warms the building in which it is installed. If no heat is supplied to that building the building will remain cold. Any temperature rise that may occur will be as a result of better utilisation of internal fortuitous or incidental heat gains.
To reduce heat transfer by convection an insulant should have a structure of a cellular nature or with a high void content. Small cells or voids inhibit convection within them and thus are less prone to excite or agitate neighbouring cells.
To reduce heat transfer by conduction an insulant should have a small ratio of solid volume to void. Additionally a thin wall matrix, a discontinuous a matrix or a matrix of elements with minimum point contacts are all beneficial at reducing conducted heat flow. A reduction in the conduction across the voids can be achieved by the use of inert gases rather than still air.
Radiation transfer is largely eliminated when an insulant is placed in close contact with a hot surface. Radiation may penetrate an open cell material but is rapidly absorbed within the immediate matrix and the energy changed to conductive or convective heat flow. Radiation is also inhibited by the use of bright aluminium foil either in the form of multi-corrugated sheets or as an outer facing on conventional insulants
Most materials achieve their insulating properties by virtue of the high void content of their structure. The voids inhibit convective heat transfer because of their small size. A reduction in void size reduces convection but does increase the volume of the material needed to form the closer matrix, this thus results in an increase in product density. Further increases in density continue to inhibit convective heat transfer but ultimately the additional benefit is offset by the increasing conductive transfer through the matrix material and any further increase in density causes a deterioration in thermal conductivity.
Most traditional insulants are manufactured in the low to medium density range and each particular product family will have its own specific relationship between conductivity and density. One particular group of products. the insulating masonry group manufacture in the medium to high density range. They improve their thermal conductivity by reducing density.
Thermal conductivity increases with temperature. The insulating medium, the air or gas within the voids becomes more excited as its temperature is raised this excitement enhances convection within or between the voids and so increases heat flow. This increase in thermal conductivity is generally continuous for air filled products and can be mathematically modeled. Those insulants which employ ‘inert gases’ as their insulating medium may show sharp changes in thermal conductivity, these changes may occur because of gas condensation but this tends to be at sub zero temperatures.
The effects of surface emissivity are exaggerated in high temperature applications, and particular attention should be paid to the selection of the type of surface of the insulation system. Low emissivity surfaces such as bright polished aluminium reduce heat loss by inhibiting the radiation of heat from the surface to the surrounding ambient space, however by holding back the heat being transmitted through the insulation a dam effect is created and the surface temperature rises. This temperature rise can be considerable, and if insulation is being used to achieve a specified temperature the use of a low emissivity system could well necessitate an increased thickness of insulation.
For example a hot surface at 550 Celsius insulated with a 50 mm product of thermal conductivity 0.055 and ambient temperature of 20 C would give a surface temperature of approximately 98 C, 78 C and 68 C when the outer surface is of low (polished aluminium), medium (galvanised steel) or high (plain or matt) emissivity respectively.
Sustainable & Ecological Practice
Cummins + Voortman Ltd. strive to incorporate sustainable design principles into all work carried out through the practice. (Green Architecture)
While this is a complex area and not linear in nature due to the many different types of projects and situations these principles are focused on 5 separate areas where much can be done to achieve sustainable design and thus reduce the environmental impact of any proposed construction work and later running costs of any proposed buildings (Lifecycle analysis).
Construction sector waste is an increasingly urgent issue. By careful early planning at design stage this can be greatly reduced. For instance pumped insulation usually involves much less waste and eliminates the numerous waste off cuts you often see going into skips!
Materials have widely varying environmental impacts. Renewable materials such as timber are much more desirable and sustainable than say concrete blocks or metals. It is in this area that Architects can make a significant input into reducing the adverse impacts and the practice evaluates every material in relation to sustainable principles.
Ventilation systems consume significant energy in use and need regular maintenance. The practice by using sound sustainable design principles tries to minimise and avoid situations where such systems are necessary.
The effective use of available natural resources and protection of both vegetative and animal habitats is crucial to the sustainable functioning of a building or buildings/development into the future.
The energy people consume in transport equals that used in buildings. Much research is being carried out on the connections between density of development, mix of uses, and environmental sustainability including land consumption and transportation where non-motorised and public transports are to be favoured. Please review the Urban Design area of this site to see how the practice puts this research to the test.