Tag Archives: eco build

Some more Thermodynamic panel info

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From a discussion on http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=9511&page=1#Item_15

Gary

I consider these as a form of air source heat pump, without a fan or finned coils. The underlying technology is well established and should be as reliable as a GSHP.

The panels are a good solution for a marine environment – I wouldn’t use ASHP units near the sea as the coils rot after about 7 years due to salt corrosion, so they would be a cheaper alternative than GSHP for such areas.

I have seen a completed installation and the owners were very happy with it.

Solar thermal it ain’t however – there is an improvement in COP when the sun is shining but it won’t provide free energy.

Chris

As far as I can find there are two manufacturers of these systems, the best known being Energie in Portugal http://www.energie.pt/ but also a company called Energy Panel in Spain. http://www.energypanel.es/productos.aspx?idFamilia=1&idProducto=1

The problem I have with them is a seeming lack of independent verification of their claims for running costs. I’ve seen mention of various installations being independently monitored but all my previous efforts to get these reports have so far failed.

Does anyone know of any such independent verification?

A nice post about Accoya wood

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http://blog.emap.com/footprint/2011/08/08/accoya-used-to-build-bridge-in-the-netherlands/

I’ve since learnt that (unless it’s changed and the info is out of date or wrong) that Accoya wood is grown in NZ & treated in the Netherlands. So the transport carbon footprint isn’t great. It’s then consequently expensive.

http://www.gowercroft.co.uk/2013/03/what-is-accoya-timber/

“The downside to this material is that while the trees are grown in New Zealand and the acetylisation process occurs in The Netherlands, it will always be expensive. The raw timber costs three times as much as our standard hardwoods.”

The geographic growing and processing isn’t mentioned on the Accoya website that does cover a lot of other good environmental aspects of Accoya:

http://www.accoya.com/sustainability/

Polar bear inspired external wall heating system

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Follow the bears

The biomimicry-based technology imitates the effect of fur on polar bears, the individual hairs on the polar bear being hollow and guiding sunlight directly to the skin. As the polar bear’s skin is black, it is able to absorb light efficiently, and convert it into heat which it transfers to the body.

http://www.building4change.com/page.jsp?id=1339

External wall insulation system (EWIS) specialist Sto has brought its StoSolar solid wall heating system concept from Germany to the UK market.

The system incorporates a translucent glass render finish covering tiny capillaries that guide sunlight to a black absorbent layer, which converts solar to thermal energy. The masonry stores this heat and releases it back into the building as radiant heat, reducing the internal heating requirement.

Low sun means high heat

The amount of heat generated by the system depends on the angle of the sun. In summer, when the sun is high in the sky, less radiant energy is absorbed by the capillaries, so the heat generated is greatly reduced. In the winter, the low angle leads to the maximum amount of sunshine being transmitted to the absorbent layer ensuring that most heat is produced during the cold months.

StoSolar integrates into a Sto EWIS and is suitable for new and existing buildings when fixed to a solid wall that is not internally insulated. It will generally use 10-30 percent of a façade’s insulating surface area and be delivered to the construction site as prefabricated units to be incorporated into an external wall system.

Recycled Foamed Glass Insulation

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28 May 2012 Update:

I put a post on greenbuildingforum.co.uk and the consistent reply is that it’s more expensive than well used and well know Leca, which is usually used with a breathable Limecrete floor. I’m not sure if it’d work / work as well under a non breathing floor.

http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=9113&page=1#Comment_147104

I was at a Green Building show / expo / day at the Eden Project last week and there was a talk by a German sounding chap, who is part of the UK Epoc Europe Ltd team promoting / pushing their TECHNOpor (Recycled Foamed Glass).

The key points seemed to be:

  • uses 100% (or close to 100%) recycled materials (glass bottles etc.)
  • German factory is powered by HEP electricity.
  • light to transport on low emmisions trucks from Germany.
  • easy to work with.
  • good insulation values for under the floor, behind retaining walls.
  • can even be used for between floor and in ceilings insulation (as super light).

I’ve found 2 UK Websites related to this:

The German site for TECHNOpor is http://www.technopor.com/English/Granulat/

The Swiss site has a great idea of using bags for when you use the Recycled Foam Glass to insulate a wall. Given that there will be 2 retaining walls, this could be great.

From www.misapor.ch:

Carbon negative bricks !

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Carbon negative bricks showcased prior to market launch

From: http://www.building4change.com/page.jsp?id=1276

Encos uses recovered aggregates and vegetable oil to make sustainable bricks

Encos’ carbon negative bricks and brick slips are set to come to market soon and are on display this week at the Greenbuild Expo 2012 show, which takes place on 9 and 10 May in Manchester.

The bricks and brick slips are made from a combination of recovered aggregates and vegetable-oil-based binders. They are manufactured using a patented method based on research carried out at the department of civil engineering at the University of Leeds by Dr John Forth into the use of alternative binders in construction materials. The process consumes no water, and produces no waste.

Encobricks and Encoslips will be the first Encos products to come onto the market. Prototype products manufactured at the company’s pilot plant have been subjected to comprehensive testing at BRE and have met the standards for fire resistance, freeze-thaw and compressive strength. The products have already been used successfully in the construction of test walls.

Environmental impact

Encos says its bricks use 80 percent less energy to make than clay bricks, and as a result produce only 30 kg CO2e per ton of product. In addition, the plants that produce the vegetable oils used in the Encos binder take in CO2.For every ton of Encos product, 70 kg of CO2 is sequestered within the binder.

But looking at their site, these aren’t yet in commercial production 🙁

“A scale production plant is now fully designed with production planned for mid 2013.”
– http://encosltd.com/products/production/

MVHR :: A Passivhaus perspective

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Reading a Passivhaus article they have these as the key Mechanical Ventilation Heat Recovery (MVHR) reasons:

  • firstly its purpose is to provide sufficient fresh air,
  • secondly it is to avoid draughts and discomfort and
  • finally it is to reduce energy demand;
    – without heat recovery, ventilation leads to unnecessary energy demand and can cause thermal discomfort.

In buildings with MVHR, fresh air is drawn in through a heat exchanger, past the stale air being extracted from the building. The heat exchanger is designed so that the exhaust air warms the incoming outside air, before it finally leaves the building. Importantly the two air streams do not mix, thereby maintaining high standards of fresh air supply throughout the home.

In order to circulate the fresh air throughout the home, two low energy fans are used; one on the supply and one on the extract. The fans only consume a fraction of the energy that the system manages to ‘harvest’ from the stale air. Measurements have shown that they can save more than ten times the amount of energy that they use.

Opening doors and windows

  • You can open windows and doors. Yes, in winter, you’d impact the integrity and efficiency of the system if you leave doors and windows for long periods of time. But even in a non MVHR / Passivhaus building, this is unlikely to occur.
    And steam, smells etc. are being naturally extracted, so this “venting” requirement is no longer there.
    In warm weather, it’s good to open doors and windows of a MVHR / Passivhaus building. Especially at night to let in the cooler air, that you can day time keep trapped in the house at that temp.

Saving energy and water :: Pipework

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An interesting GreenBuildingForum.co.uk thread.

Long +/or copper pipes mean that the amount of water that needs to flow to a tap, before you have a hot tap can be a lot. Shorter plastic (that don’t absorb the heat, until they heat up) pipes will have a big impact on reducing the amount house users will run a tap in order to get their hot water needs / desires.

Also discussed is having thinner diameter pipework. If you have enough pressure, this means there is less water sitting in the pipes between times the hot water is requested. Suggestion is 12mm pipework.

Construction (embodied) Energy Vs Operational Energy

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My Summary / Conclusion

  • In 2007, 16% of CO2 equiv impact is construction of a building, 84% is operational / in-use.
  • Today the split is roughly 20% embodied and 80% operational.
  • The modelling shows that we are moving to a CO2eq (CO2 equivalent) of 38/62% for masonry construction, and 35/65% for timber-frame construction.
  • No significant differences emerged between masonry and timber construction in terms of overall CO2 impact over the 60- and 120-year study periods. The largest difference observed between comparable masonry and timber constructions was 4%.
  • No clear / significant impact of thermal mass.
  • Emissions are cumulative, so 1 tonne of CO2 equiv at the point of construction roughly equals a tonne of CO2 equiv during the 60 year life of a building.

Which aspects of a dwelling are responsible for the largest CO2 impact?

  • Space and water heating have the largest CO2 impact in dwellings.
  • Appliances also have a large operational CO2 impact.
  • In both masonry and timber constructions, the impact of foundations and ground floors dominates the embodied CO2eq impact.
  • In masonry construction, the external walls also have a major impact.
  • Other elements, such as windows/doors and floor finishes, have a relatively large impact because they are repeatedly replaced throughout the life of the dwelling.
    • Waste water heat recovery systems have a 60 year assumed life span (windows and doors – 40, MVHR 15, flooring 10 ….)
  • The embodied impact of services was found to be approximately 5% of impact at 60 years and 7% at 120 years.

Construction Vs Operational Energy

I’ve come across some interesting figures and links to research in an article in the Green Building Magazine (by www.greenbuildingpress.co.uk).

  • Embodied Energy – a ticking time bomb (Spring 2012)

In 2007, around 16% of the CO2 equivalence impact was constructing a building.
– This covers the manufacture of materials and components, transport and construction.

84% of the CO2 equivalence impact of a building was down in use emissions.

This data is from http://www.bis.gov.uk/assets/biscore/business-sectors/docs/l/10-671-low-carbon-construction-igt-emerging-findings.pdf

That is why policy to date has been biased to making buildings more operationally efficient.

The article then makes the point that raises the importance of embodied (construction) emissions. Namely that since emissions are cumulative, 1 tonne of CO2 equivalence impact occurs for every year this “CO2” is in the atmosphere. So 1 tonne of CO2 at the start of a buildings 60 year life will have twice the impact of 1 tonne emitted during the building’s life.

The longer a tonne of CO2 hangs around in the atmosphere, the more damage it can do.

So it’s potentially dangerous to focus on carbon-intensive solutions that are installed at the point of construction, so that they reduce the operational emissions.

So, it is best to look for principles, materials, solutions etc. that will reduce both the construction (embodied) and operational energy of a building. So, as it’s often said, the general advice is still to optomise the fabric efficiency of a building before other measures.

October 2011 Update

The October 2011 report by the NHBC Foundation (“Housing Research in partnership with BRE Trust”) – Operational and embodied carbon in new build housing – A reappraisal:

Until now, focus has been almost entirely on the carbon emissions resulting from using homes, but clearly the balance between those operational carbon emissions and emissions from producing and installing the materials – the embodied carbon – needs to be considered.

This publication explores a subject which has to date lacked a strong and accessible evidence base. It looks at a range of carbon reduction scenarios as delivered through typical house types and estimates the likely impact both in terms of operational and embodied carbon – providing an insight into the contribution of different technical responses to the low carbon agenda, including the balance between operational and embodied carbon.

Evaluated Scenarios:

Twenty-four scenarios were appraised, using SAP software to determine operational CO2 emissions and BRE Global’s Environmental Profile methodology to analyse embodied CO2eq emissions.

The research considered the following variables:

  • two built forms (detached and mid-terraced)
  • two construction weights (masonry and timber frame)
  • three operational CO2 performance levels (25, 31 and 40% reductions over Part L1A 2010)
  • two dwelling lifespans (60- and 120-year study periods)
  • varying grid electricity CO2 intensity (to account for the expected impacts of grid decarbonisation).

Extracts from the report:

  • The modelling showed a typical percentage split between operational and embodied CO2eq (CO2 equivalent) of 62/38% for masonry construction, and 65/35% for timber-frame construction. These are averaged figures.
  • No significant differences emerged between masonry and timber construction in terms of overall CO2 impact over the 60- and 120-year study periods. The largest difference observed between comparable masonry and timber constructions was 4%.
  • The modelling showed that space and water heating, along with foundations, ground floors, windows/doors and floor coverings, were the largest contributors to overall lifetime CO2 impact. Appliances were also a significant contributor, but building designers have limited opportunity to reduce these emissions via their designs.
  • The typical split between operational and embodied CO2eq in new build housing has been taken as 80% operational, 20% embodied, a position largely confirmed by recent studies[1]. However, within the context of future Building Regulations requirements – which are expected to tighten to the point that new homes will be significantly lower in CO2 from 2016[2] – operational CO2 emissions are set to fall radically. This means that embodied CO2eq emissions will become increasingly significant in terms of the percentage they contribute to the overall CO2 impact of new build dwellings. In addition, typically the more energy efficient a given house type becomes, the greater the quantity of additional materials required to construct it (eg additional insulation, more services). There is also potential that such additional materials (eg renewable generation installations) may have particularly high embodied CO2eq levels. Both these considerations suggest that, as operational CO2 emissions reduce, embodied CO2eq emissions will increase.
  • The replacement of services and other building components has a direct bearing on both operational and embodied CO2eq emissions across the 60- and 120-year study periods.

Assumed lifespan of construction elements:

  • The proportion of embodied CO2eq in masonry construction was found to be higher than that in timber construction. However, this difference was relatively marginal, the maximum difference being 4%. This is because, other than the walls, the majority of building elements were similar in both the masonry and timber constructions modelled.

Which aspects of the dwelling are responsible for the largest CO2 impact?

  • Space and water heating have the largest CO2 impact in dwellings; this remains significant in all scenarios despite diminishing slightly as designs move from 25 to 40% CO2 reduction.
  • Appliances also have a large operational CO2 impact, although dwelling designers have limited ability to help achieve reductions in this area.
  • In both masonry and timber constructions, the impact of foundations and ground floors dominates the embodied CO2eq impact.
  • In masonry construction, the external walls also have a major impact.
  • Because both of these areas will last the lifetime of the dwelling, they should be considered at the design stage when seeking to reduce the overall dwelling CO2 impact.
  • Other elements, such as windows/doors and floor finishes, have a relatively large impact because they are repeatedly replaced throughout the life of the dwelling.
  • The embodied impact of services was found to be approximately 5% of impact at 60 years and 7% at 120 years. However, these results should be treated with caution as some aspects, such as controls, had to be omitted due to lack of available data, and the services were not studied in depth during this project.

Did the varying thermal mass levels have a significant impact on cooling?

  • No clear trend was identified from the modelling carried out, with minimal impact from space cooling in both masonry and timber designs.

UK Solar Hot Water Trial Findings

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The Energy Saving Trust did a survery on a large number of UK and Republic of Ireland solar hot water systems.

PDF report on the survey >>

Key Points

  • There were 54 flat-plate systems in the trial.
  • There were 34 evacuated-tube systems in the trial.
    • There was no difference in the annual solar energy yield observed between solar installations using flat-plate solar collectors and those using evacuated-tube solar collectors. This may be because although evacuated-tube collectors have higher insulation, flat-plate solar collectors generally have a larger working area as a proportion of the collector size.
So there are none of the “new” Thermodynamic Panels in the survey. These do appear to be different and better. Providing 24 hour hot water.

Distribution of the surveyed / trial locations:

So for Silver Spray in Cornwall, should get better results as more sunshine:

The solar energy input to the hot water cylinder is at a maximum in summer, with back-up heating providing more energy in the winter months.

It’s key to set the backup (non solar) heating system to run so that the solar heating can be most effective and the house occupants have hot water when desired.

How to improve the performance of a solar water heating system:

  • Using boiler timers and/or solar controllers to ensure that water is only heated by the back-up heating sources after the water has been heated to the maximum extent possible by the sun.
    • Timing of back-up heating and hot water use. Systems
      provided more energy when the back-up heating was
      used just before the main hot water use or at the end of
      the day. This provides a better opportunity for the solar
      collector to heat the water rather than using the back-up.
  • Having an adequately sized dedicated solar volume (that is, a portion that can only be heated by the solar water heating system). Where a dedicated solar volume is not used (for example in systems that do not require the existing cylinder to be changed), the timing of back-up heating has a particularly important impact on performance.
  • Insulation is a vital part of this, as systems with poorly insulated storage cylinders can suffer from inadequate hot water provision in the mornings.

Key Findings:

  • Well installed and properly used systems can provide around 60% of the years hot water.
    • Across the whole trial, the proportion of domestic hot water energy provided by solar power ranged between 9 per cent and 98 per cent (with a median of 39 per cent).
  • Plenty of other findings, see the report.

Customer / Consumer Advice

What to expect from your installer:

  • All MCS installers should be able to provide a detailed breakdown of the specification and costs of their proposed system. They should:
    • Complete a technical survey.
    • Explain how they calculated the size of the system to be appropriate for your hot water usage.
    • Provide an estimate of how much heat will be produced by any proposed system.
    • Supply clear, easy-to-understand and detailed information and advice on how best to use the system and operating instructions.
    • Explain how the system will be installed and if there will be any disruption to your property.
    • Install and set controls and settings to ensure you get the most out of your solar water heating system.
    • Provide clear and easy-to-understand information on product and workmanship warranties.