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Feb 10
2010
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How much insulation does it take to make an eco-home?Posted by: Will Homoky Tagged in: Solar , Renewable , project5 , Materials , Knauf Insulation , Great British Refurb Campaign , Energy Saving , Eco-Refurb , Design , Bristol , 10:10 campaign
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The refurbishment is well underway at our house in Bristol, which will make it the 10:10 and Great British Refurb Campaign's Home of the Future.
A notable change so far has been the arrival of vast quantities of Knauf Insulation.
Previously, our Victorian house had suspended wooden floors, solid-brick walls and just 50mm of loft insulation, - leaving it poorly equipped to hold-on to the heat we generated. Now 200mm of insulation has been added under the floors, 150mm is being added to the interior of the external walls, and 400mmm is being added to our loft space. Seeing just a fraction of this insulation piled-high in our living room gives a real sense of how much our house, along with so many other houses in the UK, falls short of such a fundamental means of energy conservation. The internal wall insulation is particularly ingenious, and seems relatively simple to install. It uses a series of joists made from marine-grade ply and expandable foam (this has much improved heat retention and life expectancy compared to timber, as Knauf Insulation specialist Nigel explained to me). Between the joists recycled and water-resistant soft glass wool panels are installed behind new plasterboard. It's the kind of thing that one could install one-room-at-a-time or in combination with other planned refurbishments, thus spreading the cost of installation. 
Previously, heating accounted for half of our estimated annual energy consumption, but following the improved insulation our heating bills should be halved, saving us around £200 and 0.75 tonnes of CO2 per year. Our old radiators failed to heat the house adequately but now we've had all this insulation installed we can actually downsize the radiators... and heat our house more effectively.
Better for us, better for the planet!
Will Homoky
Home of the Future competition winner
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written by Janet Cross, February 12, 2010
Hi, I think all that extra insulation is wonderful, but what is the plan for ensuring you get adequate ventilation? It's bad enough in a modern house - we have cavity wall insulation etc, and have to use a dehumidifier to counter the effects of drying clothes on airers rather than in a tumble dryer, thus reducing the amount of electricity we save. As I understand it, these old Victorian homes need to breath. Are you getting a heat recovery/ventilation system?
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written by Will Homoky, February 17, 2010
I think Matt makes a very good point about the miss-use of 'pay back' periods - the period it takes for accumulated energy savings to offset the cost of the initial investment.
Firstly, as Matt points out the insulation could be added to other re-decoration or renovation plans room-by-room if required - spreading the costs, and minimizing disruption to the home.
Secondly, the total pay back period for the wall, floor and loft insulation installed in our house for example is around 31 years - longer than many people may expect to be around to see overall financial gains in a single home. In this instance however, the pay back period alone can be misleading as it does not account for the benefits to the comfort of the home, or the environment. When simply re-decorating a house there are zero benefits to your energy bills or the environment, but the investment is still considered worthwhile. When improving the energy conservation of your property, you will also improve the comfort of your home, save a lot on your bills (savings of around £200 a year for us), and benefit the environment.
So perhaps rather than using a pay back period as an excuse to put off insulating the home, we should see any home-refurbishment with a pay back period at all, as a sounder investment than one without?
Firstly, as Matt points out the insulation could be added to other re-decoration or renovation plans room-by-room if required - spreading the costs, and minimizing disruption to the home.
Secondly, the total pay back period for the wall, floor and loft insulation installed in our house for example is around 31 years - longer than many people may expect to be around to see overall financial gains in a single home. In this instance however, the pay back period alone can be misleading as it does not account for the benefits to the comfort of the home, or the environment. When simply re-decorating a house there are zero benefits to your energy bills or the environment, but the investment is still considered worthwhile. When improving the energy conservation of your property, you will also improve the comfort of your home, save a lot on your bills (savings of around £200 a year for us), and benefit the environment.
So perhaps rather than using a pay back period as an excuse to put off insulating the home, we should see any home-refurbishment with a pay back period at all, as a sounder investment than one without?
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written by Will Homoky, February 17, 2010
Hi Janet, I share your concerns about adequate ventilation; this is a point I have raised with Keepmoat, the guys responsible for overseeing the refurbishment at our house, and they've assured me it is being addressed.
As I understand the ventilation in our house prior to the refurbishment was apparently poorly designed (if designed at all). We had double-glazed uPVC windows throughout, but without any ventilation on the window frames. Drafty doors and loft hatches and uncarpeted wooden floors probably allowed to house to breathe adequately, but at the expense of heat conservation in the home.
To address this easily controlled ventilation has been added to all the window frames in the house (currently a building regulations standard on new uPVC window frames), while replacing doors and loft hatches (eliminating drafts), and insulating under the floors (further eliminating drafts from the living space). These measures should allow for sufficient ventilation of the loft space, and floor joists through low-level brick vents but restrict the passage of cold air into the living space. The window ventilation should then bring the property in-line with current regulations, but allow for better control during very windy or cold periods.
It strikes me that older properties like mine, with a history of alterations probably have all sorts of ventilation characteristics, and it is worth seeking advice from a specialist like Keepmoat to look at your property holistically to see where best insulation/ventilation changes could and/or should be made.
As I understand the ventilation in our house prior to the refurbishment was apparently poorly designed (if designed at all). We had double-glazed uPVC windows throughout, but without any ventilation on the window frames. Drafty doors and loft hatches and uncarpeted wooden floors probably allowed to house to breathe adequately, but at the expense of heat conservation in the home.
To address this easily controlled ventilation has been added to all the window frames in the house (currently a building regulations standard on new uPVC window frames), while replacing doors and loft hatches (eliminating drafts), and insulating under the floors (further eliminating drafts from the living space). These measures should allow for sufficient ventilation of the loft space, and floor joists through low-level brick vents but restrict the passage of cold air into the living space. The window ventilation should then bring the property in-line with current regulations, but allow for better control during very windy or cold periods.
It strikes me that older properties like mine, with a history of alterations probably have all sorts of ventilation characteristics, and it is worth seeking advice from a specialist like Keepmoat to look at your property holistically to see where best insulation/ventilation changes could and/or should be made.
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written by John Connett, February 17, 2010
Interesting to see the use of 150mm of insulation to the interior of the external walls. Something similar was considered for my refurb. Even with very high performance aerogel insulation the loss of room space and the inconvenience involved persuaded me not to do it. My house is a small, mid-terrace with cavity walls so the benefits would be less than for many other houses.
Another possible problem that was mentioned with interior wall insulation was the loss of thermal mass. Is your refurb taking any measures to address this?
Another possible problem that was mentioned with interior wall insulation was the loss of thermal mass. Is your refurb taking any measures to address this?
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written by Wookey, March 01, 2010
Thermal mass is a double-edged sword. It only unequivocally helps in a house heated all the time. For people who go out to work a low-thermal mass building is usually cheaper overall to heat, but there are complex interactions with the type of heating used and the amount of passive solar input. Our last two houses have been made much easier to heat by the addition of internal insulation, and we prefer the faster-reacting heating. Solar overheating in summer has not proved to be a problem.
And whilst everyone is thinking about insulation, don't forget airtightness, which is just as important. Yes ventilation is required but that should be controlled ventilation through holes you know about, not uncontrolled through holes you can do nothing about. If you get your insulation and airtightness up to a decent level then mechanical heat recovery becomes a good idea. Unfortunately it's still very expensive in this country.
And whilst everyone is thinking about insulation, don't forget airtightness, which is just as important. Yes ventilation is required but that should be controlled ventilation through holes you know about, not uncontrolled through holes you can do nothing about. If you get your insulation and airtightness up to a decent level then mechanical heat recovery becomes a good idea. Unfortunately it's still very expensive in this country.
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written by Mark Sopala - Keepmoat, March 05, 2010
I work for Keepmoat - the team that made various changes to retrofit Will's house over the last couple of weeks. The property was not installed with any form of heat recovery ventilation, as the air tightness of the building is higher than the levels at which specialist ventilation systems would become a requirement. The insulation products installed in the property still allow the property to breath and with the installation of trickle vents within the windows to ensure they are to building regulation standards will also create a significant number of air changes.
It is however important that we understand what this level of retrofitting insulation will do to the property in terms of higher than usual levels of condensation. The question of good ventilation all year round needs understanding, specifically in relation to both the condensation build up and the likelihood of overheating during the summer months, with neither being dealt with by building regulations, in any more depth than the levels we are achieving.
It is however important that we understand what this level of retrofitting insulation will do to the property in terms of higher than usual levels of condensation. The question of good ventilation all year round needs understanding, specifically in relation to both the condensation build up and the likelihood of overheating during the summer months, with neither being dealt with by building regulations, in any more depth than the levels we are achieving.
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written by Bob, March 26, 2010
Reasons to consider carefully when insulating walls internally is the cost and hassle.
Remove skirtings, window boards and replace after fitting insulation. Power sockets will have to be brought forward and radiators taken off and brought forward. Dry lining the walls will require a finish so if you want a skim coat there is yet further of a plaster.
Don't get me wrong it can make all the difference in retaining heat internally but it is at a cost of more than just the cost of the insulation.
Remove skirtings, window boards and replace after fitting insulation. Power sockets will have to be brought forward and radiators taken off and brought forward. Dry lining the walls will require a finish so if you want a skim coat there is yet further of a plaster.
Don't get me wrong it can make all the difference in retaining heat internally but it is at a cost of more than just the cost of the insulation.
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written by Robert Willan, April 19, 2010
Impressive amount of insulation, but in asking about payback, why has no-one cottoned on that the payback time (if that is important to you) would be considerably reduced if the Chancellor did not charge 17.5% "Refurb" tax - i.e. VAT on the labour and materials??
Retrofitting insulation to a house already built is a nightmare. We are hoping to insulate under solid and suspended floors, on the inside of some exposed external walls and under a flat roof. In addition to the cost of demolition, materials and making good, there is the extra 17.5% VAT. What is the logic of paying tax on hidden energy-efficiency measures when the UK has to reduce its CO2 emissions?
For most people, with uncertain careers and lives, this disruption and expense are just not worthwhile; especially when the volume house-builders are building to the lowest standard they can get away with and do not pay VAT on labour or materials.
Whether or not you believe in climate change, it is intuitively sensible to live within one’s means. It seems unlikely that CO2 emissions are going to be reduced from road traffic, air travel or industry. So the onus is going to fall on the UK householder.
In order to fund the zero-rated status of energy-efficient materials and their installation, perhaps VAT should be raised on the products that use energy, or from bankers bonuses?
It is illuminating that most MPs expense claims were for tarty makeovers rather than, for example, dry lining their house and installing a ground-source heat pump! Shows how much MPs understand the problem of retro-insulating the UK's housing stock!
Retrofitting insulation to a house already built is a nightmare. We are hoping to insulate under solid and suspended floors, on the inside of some exposed external walls and under a flat roof. In addition to the cost of demolition, materials and making good, there is the extra 17.5% VAT. What is the logic of paying tax on hidden energy-efficiency measures when the UK has to reduce its CO2 emissions?
For most people, with uncertain careers and lives, this disruption and expense are just not worthwhile; especially when the volume house-builders are building to the lowest standard they can get away with and do not pay VAT on labour or materials.
Whether or not you believe in climate change, it is intuitively sensible to live within one’s means. It seems unlikely that CO2 emissions are going to be reduced from road traffic, air travel or industry. So the onus is going to fall on the UK householder.
In order to fund the zero-rated status of energy-efficient materials and their installation, perhaps VAT should be raised on the products that use energy, or from bankers bonuses?
It is illuminating that most MPs expense claims were for tarty makeovers rather than, for example, dry lining their house and installing a ground-source heat pump! Shows how much MPs understand the problem of retro-insulating the UK's housing stock!
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What's your gas bill like? Unpredictable? How much do you spend on electricity? Too much? Wouldn't it be a joy if those bills just evaporated or at least shrank? 
What is to stop any house owner doing internal wall insulation room by room, just as they would do for re-decoration, thus spreading the cost? Of course, those with cavity walls would probly need a professional.
Underfloor insulation could also be done room by room in most cases.
I cannot understand the resistance to adding adequate insulation. The excuse often given is the length of the 'pay back' period. When people decorate their rooms or add furniture or renew kitchens, do they ask about a 'pay back' period?