Cornwall based sustainable furniture

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I’ve got some ideas for a table made from recycled wood and maybe recycled steel. The more of the house (build, materials AND furniture) can be recycled:

  • Built in a way that can be recycled in the future
  • Be built from materials that have had a previous life

the better.

So great to come across St Austel based www.sustainable-furniture.co.uk who also have a showroom in Truro.

 

Single Vs Double Glazing

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I’m going to have a problem, sorry challenge.

The sliding doors from the planned living room at the bottom are due to be around 2.8m tall.

This is taller than most companies produce triple glazing. In part due to the total weight of the glazing units.

Triple glazing gives better insulation, and less thermal gain. But as this is north facing, the solar gain isn’t an issue.

  • The very best double glazed windows are already capable of being net heat contributors over the course of a heating season. In contrast, triple glazed windows slightly reduce the heat absorption characteristics of a window.

BUT, how much more expensive is triple glazing and how much better is it ?

  • http://www.homebuilding.co.uk/advice/key-choices/green/triple-glazing
  • Current Building Regulations insist that any window you install today should have a U-value no worse than 1.6.
    – for  reference, walls should be less than 0.3. So windows are a thermal weak spot.
  • PassivHaus standard requires triple glazed windows with a Uvalue of no more than 0.8.
  • Although a U-value as low as 0.8 sounds very impressive, the additional energy we are saving is minuscule whilst the payback time for triple glazing (like double glazing) is high compared to other energy-efficiency improvements. So why bother ?

The key benefits are really to do with comfort. If you insulate the walls, roof and floor of a house, and you ignore the glazing, you end up with cold spots surrounding the windows at night, which cause draughts, draw heat away from you if you sit next to them, and can result in streams of condensation running down the panes. So, in essence, the standard of glazing has to match the standard of the insulation elsewhere in the house, so that the warm wrapping around the house performs consistently.

The PassivHaus Institute, in Germany, has looked at the surface temp­eratures on various forms of glazing when it gets really cold outside, and the internal air temperature is designed to be at 21°C:

  • Next to a single-glazed window, the internal surface temperature is around 1°C.
  • Next to a double-glazed window (2000 vintage), the surface temperature is around 11°C.
  • Next to a modern, energy-efficient double-glazed window, the surface temperature is 16°C.
  • Next to a triple-glazed window, with a centre-pane U-value of just 0.65, the temperature is 18°C.

So whilst triple glazing may make little difference to your heating bills, you will notice the difference inside the house.

BUT, this is all based on the situation in Germany, where it’s a lot colder than the UK. Cornwall is itself a relatively warm bit of the UK.

The upshot of this is that there are many who argue that triple glazing simply doesn’t make sense in a climate like ours. Triple glazing is more costly to produce, produces much heavier sections and has an embodied energy approximately 50% higher than double glazing.

An alternative option that might make more sense is to revisit the traditional practice of drawing curtains across windows after dark. It may be low-tech, in comparison with glazed cavities filled with krypton, but it’s something of a natural British habit and it does cut down on heat loss. Perhaps it’s time we paid attention to improving the heat retention characteristics of curtains and blinds, rather than continuing to engineer glazing units to ever lower and lower U-values.

  • Maybe, as a life style strategy, I’ll have curtains, that I might only draw when I go to bed, or some time after it gets dark. But curtains and top efficiency double glazing could be the way to go.

UK Government delay Feed In Tariff Cuts

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At yesterdays Green Building Event at the Eden Project the news came through (Tweet feeds) that Greg Barker, the UK government energy and climate change secretary tweeted:

“Having listened carefully to industry, we are looking at scope for pushing back a little the next proposed reduction in the solar tariffs.”

They were due to be cut in July from the current 21p per Kw.

If you have / get solar panels there are several return on investment streams:

  • Generation tariff – your energy supplier will pay you a set rate for each unit (or kWh) of electricity you generate. Once your system has been registered, the tariff levels are guaranteed for the period of the tariff (up to 25 years) and are index-linked. For a full list of generation tariffs, see FIT payment rates published by Ofgem
  • Export tariff – you will get a further 3.2p/kWh from your energy supplier for each unit you export back to the electricity grid, so you can sell any electricity you generate but don’t use yourself. This rate is the same for all technologies. At some stage smart meters will be installed to measure what you export, but until then it is estimated as being 50% of the electricity you generate (so that if your solar PV system is less than 30kWp you do not need to have an export meter fitted)
  • Energy bill savings – you will be making savings on your electricity bills , because generating electricity to power your appliances means you don’t have to buy as much electricity from your energy supplier. The amount you save will vary depending how much of the electricity you use on site.

One of the Eden Project show talks had these figures, that may be high end in terms of them being from a chap that is from a PV installation company.

The Energy Saving Trust has figures of:

A typical domestic solar electricity system with an installation size of 3kWp could earn:

  • £530 a year from the Generation Tariff
  • £40 a year from the Export Tariff
  • £100 a year reduction of current electricity bills

Scaling this up to a 4kWp system that’d be £893.

Being fair to Tony at Cornwall Solar Panels (Tel 01872 562 775) who gave the above figures, his entire talk was centred around there being no such thing as the best solar panel, but the best solar panel configuration for a particular situation. Panel efficiency, shape, size, drop off with heat, drop off with shading, the roof angle and a bunch of other variables (string or per panel inverters) all influence the efficiency and the system cost and so the Return On Investment (ROI). His talk went over about a dozen different installations they’ve done and have figures from. The clear implication / impression is that they are doing installations all over Cornwall.

 

Window Efficiency Article

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Houzz have this US biased article on Energy-Efficient Windows: Understand the Parts

Window Frames

All have their advantages and disadvantages, but the U.S. Department of Energy (DOE) recommends vinyl, wood, fiberglass or composite. (Aluminum is easily heated, so it isn’t a great insulator.) Wood has efficiency problems due to expansion and contraction, so consider aluminum- or vinyl-clad windows. But if you choose vinyl, consider an insulated version, depending on your climate and house requirements.

Window elements from http://www.energysavers.gov/your_home/windows_doors_skylights/index.cfm/mytopic=13370

Window Glazing

Different gas fills impact cost and efficiency.

The most common gasses used are argon, which is relatively less expensive, and krypton, which is more expensive but has a better ability at decreasing a window’s U-factor.

Tints and inner glass layers or spectrally sensitive coatings can impact the U-Value.

Low-E coatings. These coatings increase a window’s cost by 10 to 15 percent, the DOE says, but they can reduce energy loss by about 30 to 50 percent.

For keeping heat inside the house in the winter, the coating should be on the inside of the glass.

 

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.

People really do like to be beside the seaside !

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http://www.bbc.co.uk/news/education-17743980

The songs and postcards appear to be right – a study suggests we really do like to be beside the seaside.

The study of 2,750 people presented to the British Psychological Society examined the effects of different types of outdoor environments on people.

Researchers found the bracing seaside air had a more positive effect than the countryside or an urban park.

Researcher Mathew White said it could reflect an “innate preference” for the sights and sounds of water.