A modern version of the typical ‘block-built’ wall system uses insulating blocks which are manufactured using aerated concrete, pumice, ash and other lightweight aggregates.

Insulating concrete is a different form of construction that has appeared over the years in various guises. Recent forms of this building method use an insulating mould or shuttering system for walls and normal concrete is poured into this to form the load-bearing part of the wall. A less well-known type of cast insulating concrete was tried in the USA after WWII.

Diatomite and Wood-Fibre Concrete The US version was an experimental mix of sawdust, wood-shavings, diatomaceous earth, cement and clay. The sawdust and wood shavings replaced the sand and gravel found in normal concrete and as diatomaceous earth is used in industry for its insulating and fireproofing properties, this provided the fire retardant element necessary for the mix. The resulting concrete was found to be not as strong as normal concrete but this could be solved by building a cavity or double skin type wall with one ‘leaf’ of the wall providing the structural strength.  

More importantly, the ‘sawdust’ concrete used less cement and was reckoned to have about 12 to 14 times the insulation value of ordinary concrete. It has proven to be long-lasting with no significant deterioration of the buildings which have been built with it. The product can be cast in relatively thin slabs and can be drilled and sawn; and also plastered or sanded to produce a finish suitable for painting. It is lightweight and suitable for internal walls, floors and even the internal part of roofs; and can be reinforced if necessary.

Availability of Materials       Sawdust and wood shavings are easy to come by if you live near sawmills, although the variety of timber and even the age of the sawdust can affect the quality of the finished product. The best known source of diatomaceous earth in Ireland is found in the Lower Bann Valley, and it can also be obtained from suppliers of industrial minerals. Note that there are some health and safety precautions associated with certain commercial varieties. Clay is a common feature in most areas and cement is obviously available from builders’ merchants anywhere.

The actual mix requires knowledge of the qualities and quantities of the various constituent parts and could benefit from the addition of other environmentally friendly materials.

If anyone is interested in experimenting with this interesting building material, please get in touch through the website and I will be keen to help and advise.

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Hi All,

Relax, this blog will be short and sweet!

I recently co-wrote an article for Selfbuild magazine with the editor, Astrid Madsen - entitled 'Waste Not, Want Not'. It is published in the Summer 2010 issue and should be available from local bookshops or newsagents.

The magazine is a very useful resource for information on all aspects of building and if you wish, you can subscribe to it at the following link http://www.selfbuild.ie/selfbuilder/magsub.htm

Happy reading.

P.S. If you can't obtain a copy - I have a spare one which I can post out (free) to the first person who asks me! Just leave your request here

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Go here for a copy of the full Case Study.

The Brief ...

I was asked about a year ago by a client to make a planning application for a large commercial building on his site in rural County Tyrone. The proposed steel-framed building was to be dismantled from a commercial site in England (where it had been found by the client) and re-erected in its new position.

The Planning Application …

The process of obtaining planning approval was long and arduous and the main objections concentrated on issues such as the alleged environmental impacts of noise, pollution and traffic. These matters were eventually cleared up to all the consultees’ satisfaction and the design was ultimately approved.

The Structural Design …

The general dimensions of the shed were obtained early in the design stage in order to make the planning application; however detailed dimensional checks were done after the building was dismantled on its previous site and shipped over to the new site. In order to check that the re-erected shed would meet with current building regulations, the structural engineering survey examined points such as:

• Quality of the steel beams and columns - e.g. had they been damaged irreparably through corrosion, excessive loading or fire?
• Were the structural steel members of sufficient size to carry the new loads expected of them?
• Were structural connections of a suitable size, with bolt holes in the positions required for the new structure?
• Could the steel cladding be re-used and still provide a weather-tight system?
• Were there enough bracing members and cladding rails and purlins of the correct dimensions?

Some alterations to the original design were required; such as additional bracing, fire protection and new baseplate connections. New doors were required and the shed would need to be repainted. A new reinforced concrete base and column and wall foundations were obviously also needed. As a precaution against the possibility of receiving old over-stressed bolts, all connections would be fitted with new bolts.

When the survey and subsequent structural engineering design was complete, the costs were calculated by a quantity surveyor and the total project was found to make a considerable saving over building with all new materials. The difference was estimated to be in the region of a 20 - 25% saving to the client.

All that remains now is for the project to be built (it is scheduled to begin in late summer, 2010).

Go here for a copy of the full Case Study.

Surface water run-off from roofs presents the eco-designer with some problems – but as we all know – problems provide us with opportunities for improvement. Green roofs are well known solutions to slowing down and reducing the amount of rainfall that eventually finds its way back into our groundwater. There is an alternative to this approach ...

THE BLUE ROOF:              The blue roof avoids the necessity for heavy planting materials as required by the green roof, by simply storing excess rainwater in rooftop gullies, channels or gutters. This water is released using flow control devices and can be used for almost any non-drinkable purpose. It can be released to a stormwater harvesting system for later reuse as well as an infiltration system that recharges groundwater, or released slowly as in the SUDs solutions discussed in previous blogs. The blue roof can therefore reduce the costs of installing a traditional drainage system and can replace – or be used together with a lower-capacity SUDs * system. The ratio of captured/discharged runoff is designed to closely mimic the pre-construction hydrology of the site.

APPLICATIONS:                 The easiest opportunity for using a blue roof occurs in a long, flat roofing style normally seen in commercial development. These roofs typically have wide gutters and a good watertight liner. Blue roofs work especially well in highly urbanized areas where there is less space on the site for stormwater detention or where large, highly impervious areas generate a rapid rate of stormwater runoff that can overwhelm drainage systems and cause flooding.  The blue roof can also be used on domestic buildings if planned in advance – and it can solve the old problem of how to get rainwater back up to a level where it will provide gravitational flow to its end-use system.

IS IT SUITABLE FOR YOUR SITE?        Sustainable building design isn’t about which method is better than the other -- it’s about how we consider all the alternatives in any given situation. There are many projects where a blue roof design could benefit both the environment and the client’s requirements. As always – get professional advice early on in the design stage of your project if you want to consider any unusual or inventive eco-building solutions.

* SUDs - please see previous blogs

Water and Suds.

 “Water levels in our rivers are down by 80% during low water conditions in comparison with 100 years ago” This comment which was made by an angler was discussed in a Foyle Angling Report (http://www.loughs-agency.org/angling/angling_reports

Various reasons were cited as causing this, such as major changes in land use, urban development, drainage, forestry on upper catchments, loss of the ‘sponge effect’ and water abstraction. Among the solutions discussed to combat this was the concept of ‘SUDS’. The comment on low water interests me because I have designed some SUDS solutions for surface water drainage on some new developments recently. Regarding the waterways in our area I can only say that years of agricultural (grant aided) drainage schemes have totally ruined them. I suppose there are other factors involved, such as pollution etc, but I can remember as a boy seeing large salmon taken from our local burn which is only a few feet wide. Then the Water Board (as the Rivers Agency was then known) came along and dredged out the local river and its tributaries and that was the last we saw of salmon (or brown trout for that matter) in our small streams.

SUDS:                       ‘SUDS’ is an acronym for ‘Sustainable Drainage Systems’ or ‘Sustainable Urban Drainage Systems’. Either way, it describes a means of reducing the environmental impact due to surface water run-off from the built environment. There are many ways to slow down, attenuate and filter the water that runs off our roofs, driveways, pavements and roads. By doing this we hold water upstream for longer periods and thereby reduce flooding in downstream, low-lying areas. There are other important environmental benefits and these can be read in further detail at http://www.ciria.org/suds/ .

SOLUTIONS:           I would like to see the Planning Service adopt the principle of SUDS as mandatory for ALL new development including single houses, renovation works and commercial sites, etc. I would hasten to point out that the cost of a well designed SUDS solution can often be much less than that of a conventional surface water drainage system.

To take the idea a stage further, we can often easily incorporate SUDS along with a pond, marshy wetland or bog garden in a suitable corner of our site, and attract some interesting wildlife in the process. Other solutions can include reed beds for effluent treatment, re-cycling ‘grey’ water and using water butts for watering the garden or washing the car (using natural detergents of course).

By using our water wisely before we drain it away, we reduce the load on our fresh water reservoirs.

By the way, who thinks that imposing water charges will encourage the average householder to conserve fresh mains water? – but of course that’s another debate entirely. As usual, feel free to comment below ...

One of the nine categories of the new Code for Sustainable Homes (see www.communities.gov.uk) is that of the level of water use. Even if the Code does not apply to where you live, it is a good step towards achieving sustainable houses and it is worthwhile to have a look at what it covers.

Apart from the moral environmental sustainability issues of water conservation, the proposals for water metering (i.e. pay-for-use) will provide additional incentives for us to reduce the amount of water we use. Water usage between similar house and family sizes can vary significantly, so the water usage calculator at http://www.taptips.ie/water-usage-calculator.htm is a useful tool for you to obtain an idea of how much water is used in your household.

Water Efficient Products    A wide range of products now exist to diminish our hitherto wasteful use of water in the home. We can install low-capacity W.C. cisterns and baths, shower restrictors to lessen water flow, efficient water taps, and water regulators.

Other solutions are also available; a urinal for instance is an excellent water-saving (and hygiene) feature in a household with a few male occupants and an aerating shower head will use much less water than a ‘power shower’ and will still give a refreshing effect. A useful guide to water efficient products is to be found at www.water-efficiencylabel.org.uk - and view the Products directory. Their ‘Top Twenty Tips’ for saving water in the bathroom also gives good commonsense advice.

Appliances          Water consumption information is usually listed separately from the energy efficiency labels on all new washing machines, dishwashers and driers, etc. Guidance on this is to be found at http://www.environment-agency.gov.uk/static/documents/Leisure/cwb_ch4_appliances_880694.pdf

Re-using building materials can be as simple as visiting a salvage yard - or more complex such as targeting a specific building that is to be demolished and taking as much out of it as is possible to re-use.

What Can You Re-use or Re-cycle?

• Concrete, concrete blocks and concrete bricks, etc can be crushed and used as aggregate for hardcore fill. Some contractors now produce this material from their demolition works.
• Blocks and bricks can be re-used to build walls if all the old mortar & plaster is knocked off them. This is a very labour-intensive process and it is often better to use them where the jointing is not a visual or structural priority - such as in rustic garden walls, random paving or as kerbing around garden beds, etc.
• Much of the timber taken out of old buildings is re-usable (but check for infestation or rot), as are any materials that can be removed without damage such as slates & tiles, stone quoins, stone sills, flagstones, etc.
• Plumbing and electrical fittings can often be easily refurbished for re-use – as long as they meet current regs.
• A new building can easily be designed to accept 2nd-hand windows, doors, fitted furniture and other joinery. Glazing units will need to achieve the minimum standards for thermal insulation – so check this before you buy! Fire doors will need certificates to satisfy building regulations.
• Cladding (steel or aluminium, etc) can be saved from old sheds and re-used in appropriate locations. Just make sure it can be successfully weather-proofed again.
• Structural items such as steel beams and columns are easy to re-use - but reinforced concrete is not so simple (although it can still prove useful). Structural calculations will be required before you use any of these.
• Heating equipment can also be re-used as long as it is serviceable, however many older installations might not possess the level of efficiency required for new building regs. Again, this is not a major problem if the old system can be left out of the calculations. An example of this is where a solid fuel stove or an old range could heat a conservatory which is not heated by the dwelling's system.

What Do You Avoid?

• Avoid materials which have been contaminated (oil, sewage, chemicals, etc).
• Avoid hazardous materials (asbestos, certain fibre products, lead products including paints, etc)

The answer to “What Can You Re-cycle or Re-use?” – is - almost all building materials!

This is a wide-ranging subject, and I will come back to it again in the near future.

As with all advice given on this website – always obtain professional advice that is specific to your particular situation – before you embark on your building project.

FIRST STEPS:

Rising energy prices and the slowdown in house sales have caused many to re-think their priorities. I have noticed a big rise in the number of people looking to improve their house instead of building a new one, and high on the list of discussion subjects is the question “What is the best way to reduce my heating bills?” No surprises there then!

ENVIRONMENT:                

Some statistics are in order at this stage: Nationally (for the UK), domestic housing emits about the same amount of CO₂ as road transport. Factor in the amount of emissions caused to manufacture the materials used to build the houses and we see that our homes are a source of more than half of the total CO₂ emissions. ‘Space heating’ is a term used to describe a system that heats (or cools) the spaces in a building, but when you think that about 53% of CO₂ emissions from homes are due to space heating systems, the term might also be considered as ‘heating space’ i.e. in the cosmological sense!

SOLUTIONS:                      

There is no single way to achieve energy efficiency, but preventing heat loss should always come before considering alternative energy sources. Just as some people have found a new diet that works for them, every house has a solution which gives the best improvement in performance for your money. Your house needs to be examined in detail to discover what needs to be done.

INITIAL APPROACH:        

Professional advice at the start can save time and money – OK I know I’m biased here - but I’m also right! Good advice will specify exactly what work is needed and what it will cost; and will not follow trends blindly or encourage you to buy new technology without first balancing the environmental benefits.

This first survey or examination can be as simple or as complex as you wish to make it – but I try to follow the old ‘KISS’ rule.

After assessing structural stability and weatherproofing, the two main points to address are:

1. Insulation – What if any, insulation exists? Add to it or replace it and bear in mind that building regulations are a basic standard and not the optimum specification. Think ‘outside the box’ if necessary.
2. Air Permeability – How badly does your house leak air? (Tests can be carried out if required.) Leaky points are not always obvious, and although some ventilation is required, it should be ‘controlled’ ventilation. Fix the unwanted leaks and consider if you really need that open fireplace!

This touches briefly on one aspect of eco-building. If your interests are in new build, good thermal performance is much easier to obtain.

I will discuss methods of achieving higher energy efficiency in future articles.

The ‘Zero Carbon’ concept for new buildings has been widely discussed. There is a growing realisation that new buildings will not be truly zero-carbon unless everything in the sourcing, processing, transportation, manufacturing, building and end-of-life processes have been achieved without producing carbon. As you can appreciate, although possible - this will take some considerable time to achieve. In the meantime it is easier to achieve a no-new-carbon building. For further ideas on achieving this, keep updated on these blogs. For answers to a particular question, please contact me.

Building energy efficient homes is important, but no system will work properly if the users abuse it. As an example, think about how many ‘computer problems’ are not really computer problems at all. Many of the trends of building usage over the last few decades have been going in a direction that must be reversed – higher indoor temperatures, whole house heating, a proliferation of new electronic appliances, some of great energy consumption and so on.

Energy Reduction…   

There are four distinct parts to the energy reduction in buildings:

1. An improved thermal & air-sealed envelope for buildings
2. More efficient appliances and building controls
3. Decarbonised sources of energy, whether from the grid or locally generated
4. Changes in personal attitudes and behaviour in respect of the profligate use of energy.

The first three are matters of engineering, and the last a matter of psychology and sociology. I believe that the last is as important on its own as the first three put together.