Cambridge Eco Homes 2011 Launch


Sunday, June 12th, 2011. 11:29am


Open Eco Homes Logo

Eco Homes in Cambridge are Open on the 18th and 26th of June 2011

On the evening of Friday the 10th of June 2011 I attended the Cambridge Eco Homes launch event in St Luke’s Church Centre on Victoria Road in Cambridge.

Cambridge Eco Homes is an event run by Cambridge Carbon Footprint. They organise two days where owners of particularly “eco” homes in and around the city open them up and run guided tours. The homes are all listed online, along with downloadable case-studies describing their eco features.

The launch event was mainly an “ask the experts” question and answer session, the experts were:

The event was chaired by Liberal Democrat Cllr Sian Reid (Newnham) as Leader of Cambridge City Council. Cambridge’s Mayor, Cllr Ian Nimmo-Smith was also present, but he attended incognito, in plain clothes (no chain, gown or hat) and played no official role in proceedings.

Cambridge City Council and South Cambridgeshire District Council were listed as one of a number of sponsors of the event, along with building supplies merchant Ridgeons.

My Views

  • While there were two representatives of Housing Associations present, and the two councillors, overall it appeared to be mainly a group of rich home owners almost exclusively over fifty. I am concerned that public funding for events like this, grants, and subsidies such as feed-in-tarrifs and grants for home improvements are focusing scarce public resources on the well-off. There was no discussion during the evening at all about what could be done to encourage making privately rented homes more energy efficient, or about things like loans for investment which could help those without large amounts of money to spend to improve their homes.
  • All discussion focused on what individuals can do within their own homes; there was no discussion about those living in an area working together towards a more energy efficient way of living.
  • While it’s great to see events like these, I think the biggest and most challenging questions are really elsewhere when it comes to working out how we’re going to keep the lights on and our homes warm into the future. Stopping our increasing dependence on imported gas from ever further away and less reliable sources and generating more of our energy here is also critical. I think the passion and interest could be better channelled, but it is easier and more rapidly rewarding to make a small change in your own life than engaging in debate with others and trying to change the way the city, country and world is run where it will be less clear if you’re personally having an impact.
  • I’m always skeptical when I hear of people working in the public sector with job titles like “Senior Sustainability Officer”. It was good to see one appearing in-person in-front of some of those who pay taxes to support such positions. I was unimpressed with the officer’s level of knowledge/preparation and from her performance couldn’t clearly see what value having someone in that position in the council adds. I dread to think what the mere “Sustainability Officers” would be like if this was a “senior” one. Cambridge City Council has 1,200 staff – I’m astonished by that figure I can only presume there are lots more where this “Senior Sustainability Officer” came from.

Question and Answer Session

Insulating a Nine Inch Solid Brick Wall

Cllr Reid picked how to insulate a nine-inch solid brick wall as the first question out of those which had been submitted. As chair she chose the questions put to the panel from those submitted on paper just before the session started; those attending were given the opportunity to both contribute to the answers and ask follow-up questions.

This is clearly a question of particular interest in Cambridge given its large stock of Victorian terraced houses.

One of the panel related his experience of externally insulating his house in Cambridge, on Sleaford Street, about thirty years ago. (This house regularly gets cited at events such as these, and in council meetings, but I appear unable to find a link to any details or a picture). He described it as a very simple process of simply sticking four inches of polystyrene to the outside of the house and rendering on top.

Someone pointed out it gets a bit more tricky around windows and doors etc.

Follow-up questioning initially focused on the potential for increased internal condensation as a result of better insulation; the suggested solution being to continue the insulation below ground level.

The Energy Saving Trust‘s good practice guides were recommended by the panel. I see they have a webpage on Solid Wall Insulation, which covers external insulation.

Internal insulation was then discussed. The key problem being the loss of space inside, what in Cambridge are generally already small homes. Phenolic-foam products were reported to be the most efficient insulators for a particular thickness. (Details from the Energy Savings Trust).

A question was then asked about planning permission for external cladding. The council officer stated that if a property was not listed and not in a conservation area no planning permission was required, though building regulations would have to be adhered to.

The English Heritage Historic Environment Local Management (HELM) website was recommended for advice in relation to older buildings.

A question was then asked about homes which were built right up to the pavement. The council officer responded to say planning permission would be required in such cases (a response which I didn’t think those present appeared to think was accurate). Audience members chipped in to note that there were specific things permitted to overhang the highway such as window sills and guttering, the implication was made that external insulation was not one of them. Another member of the audience commented that essentially cladding in such circumstances would be extending a home onto land you did not own.

The idea of external insulation on the first floor only was suggested, but members of the panel advised this would result in a “leaky” overall result.

Asked about getting planning permission for external insulation in a conservation area the council officer stated it would be “not impossible”, but advised that things like both halves of a semi-detached building opting to go for it together might help in gaining permission.

Notably she did not offer up any examples of where such permission has been granted in Cambridge.

Insulating Old Wooden Doors and Windows

The second question was also on insulation, this time doors and windows.

A member of the panel said that if the country was to meet its CO2 reduction targets most of the country’s windows would need to be replaced.

The price of a well insulated new external door was quoted at £800; cheaper bodges were also offered up, with Council Leader Sian Reid reporting that her husband, former county councillor, Alex Reid, had used magnets to stick an extra layer of glazing to their front door. A heckler queried the need for magnets and said they’d done something similar using gaffa tape.

uPVC windows were then discussed, a question being asked about how long the “carbon payback” takes, when accounting for their production. The panel were unable to answer this, but said in terms of energy saving the cost payback ought take about five years. The panel were scathing about uPVC windows, both in terms of the time they last and their “carbon payback”.

Curtains were then discussed; with it being reported that with a blackout layer, or better a special thermal layer, they can be as good as double glazing for insulation. Cllr Reid reported that since she learnt that she had been obsessively closing the curtains in her house. (Shortly afterwards she clarified that she only closed her curtains when it got dark).

The importance of doing things in the right order, and having a plan, was stressed. One person asked if when insulating an inaccessible roof space it was best to take the roof off or ceiling down. One panel member replied taking the roof of had been no hassle for her (though admitting her builders had actually done it).

Photovoltaic Panels

The first question on PV panels was if you need a south facing roof. The answer was that an east or west facing roof has has only 15% less power producing potential than a south facing one. A flat roof is also only a 15% or so reduction on a perfectly angled roof.

A problem that flat panels need cleaning was raised; Andy Rankin agreed but pointed out that an array of inclined panels could be installed on top of a flat roof (though such an installation needs planning permission – as permission is needed for panels which extend above the roof-line more than 200mm).

Mr Rankin added that as pannels were getting cheaper there was no longer such a need to put them in optimum locations (or space them so they fully didn’t shade each other in such an array).

The risk of the Government dropping feed in tariff rates as soon as before the end of the year was discussed.

The lifespan of panels was discussed. Mr Rankin said they were very simple, with not much to go wrong. He suggested life spans of 25-40 years. A heckler pointed out the inverter was more complex, something Mr Rankin agreed with,

Further discussion of planning permission for solar panels was discussed. The planning officer told those present that up to nine square meters could be installed in a garden without permission. Mr Rankin commented that this was restricted to not being within 5m of a boundary (so not applicable to most city gardens) and in any-case nine square metres won’t produce much power.

Heat Pumps

The question which kicked off the heat pumps discussion was on if they could be integrated with existing central heating. The answer given was essentially no, as more efficient radiators (such as fan assisted ones) are needed to heat rooms from tepid rather than hot water.

Ground source heat pumps really need a field (for the type that have pipes about 1-1.5m under the ground); so air source are perhaps better in a city, but air source pumps are noisy and there have been planning issues elsewhere. The panel member from AC Architects said their offices on Victoria Road had a drilling rig brought in to drill a hole for a ground source heat pump, but reported that experience left her thinking that too wasn’t really appropriate for a city garden.

Rain Water

Going off the focus on heating, onto how to re-use rainwater, one panel member suggested not doing any more than having a water butt for the garden in Cambridge given the relatively low rainfall.

Another panel member said they did trap rainwater for use inside, eg. for washing allotment veg.

The panel advised against systems for re-using shower / sink waste water for eg. flushing, due to the amount of soap and fats in it which lead to tanks of smelly sludge. Simple re-use eg. taking such water outside to use in the garden on occasion was suggested.

Financial Sense

The last question was about the fact that once someone has taken the low-hanging fruit then further moves to make a home more energy efficient get more expensive and make less sense financially.

One panel member said:

You can’t spend enough to save the world

another said:

In the future people will laugh at the non-upgraded homes

It was a good job this was the last question as they appeared to be losing the plot after quite a rational and sensible start.

Wrapping Up

Asked for some final bits of advice one made the important point that efforts to insulate your house should not be at the expense of your health – through damp, mould, carbon monoxide poisoning, asthma etc. arising from making a home too airtight.

Lastly an audience member threw in a question about how he could deal with his cold concrete floor, and what he could insulate it with. One member of the panel offered a suggestion for insulating material, another suggested the best thing would be to excavate and insulate it underneath and keeping the concrete slab at room temperature.

Wrapping the session up a plug was given for the Carbon Conversations Groups.

See Also

6 comments/updates on “Cambridge Eco Homes 2011 Launch

  1. Tim Morley

    Wish I’d heard about this event before out happened, but thanks for the informative write-up. I’m just moving from the planning to the action stage on a renovation project on a1930s semi, so this is all good stuff to know.

    Personally I can’t see anything wrong with internal dry lining. Yes it takes up a small amount of internal space, but once it’s been there a couple of years, can you really see yourself saying, “Oh, this room was so much better when it was 7cm longer”? It’ll look like exactly the same room, just cheaper to heat to a higher temperature. What’s not to like?

  2. Richard Taylor Article author

    Thanks Tim,

    Have you seen how small many of the Victorian Terraces are in Cambridge.

    7cm matters in a room that’s only 2m wide.

    (Also there’s still time to make an appointment to go around some of the open houses)

  3. Tim Morley

    True, the smaller the room, the more difference the 7cm will make; but even so, could you actually tell the difference between 1.93m and 2m without measuring it?

    Let’s put it another way. Imagine you already have an insulated house with a room of ~1.95m wide. Someone comes along and offers you a grand, along with 7 extra centimetres in that room — think of all the things you could do with 7 more centimetres! The only downside is that your house will be colder for ever from now on, but that grand will help with the heating bills for a few years. Would you take it?

    I suspect that for most, the answer would be “no”; in which case, it’s only the fear of change that’s holding them back. Get on with it! :o )

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