You don’t have to think about insulation more than a few occasions in your life so when you do, take some time to learn what it really does and make sure you make the best choice for you and your home.
Why is insulation important?
It’s a fact that insulation saves heat and it’s a fact that heat costs money. So it’s a simple fact that if you’re saving heat you’re saving money. So the more you insulate the more money you save. All insulation saves more money than it costs so don’t think of insulation as costly.
When you first look in the loft you can see the state of the old insulation and how it has slumped and degraded. The last thing you should want to do is add a layer of what’s up there already. If you do, some day you’ll return, look at the same scene and repeat the same exercise. Instead, use something that won’t slump or degrade. Why not use something that is thermally bonded with recycled polyester to ensure the insulation retains its loft? Buy something that lasts, then once you insulate, you won’t have to do it again.
What is the main role of insulation?
The main role of insulation is to reduce heat loss. Two things influence its ability to reduce heat loss; the physical properties of the material itself and its thickness. The former is represented by the k value and the latter is taken into account in the U or R value. The U value is the inverse of the R value. When it comes to the k value, the lower the number the better. For the U value it’s the same and for the R value, the higher the number the better. That’s because the R value is the inverse of the U value.
What to consider
The amount and type of insulation you need depends on how much energy you need to save and space available. You may prefer certain types of material and some other features may help more than others. Insulation does much more than lower heat loss. Think of these features before you make a final choice and you will benefit much more from the end result.
Don’t just look at the k value. It’s easy to think that the lowest k value is the best. But you can get much better performance and value for money using a thicker layer with a higher k value. What’s more, a thick layer of insulation can help more to reduce noise and heat gain. A thick layer of natural fibre insulation will also improve breathability.
The benefits of insulation
As we have said, insulation does a lot of things. As well as keeping in heat, it helps manage summer heat gain. It helps with moisture and humidity levels, reduces noise and improves sound quality. It can improve indoor air quality, ease of build, sustainability, health and well being. Insulation can make up 50% of the volume of the building so these other features can provide very significant benefits.
How to choose the best insulation?
So how do you go about choosing what’s best for you? It depends on where you want to insulate and what you want to get out of the insulation. We’ve given some ideas below to give you some food for thought.
If you’re looking to insulate your loft, bear in mind there is plenty of space to work with. With the amount of space in most lofts you will be able to install a deep layer of insulation. This means you don’t need to focus so much on a very low k value. Instead you can create a good layer of insulation by building up a deep layer with a regular k value. Even if you want to board part of your loft you can use loft legs to raise the level of the boarding. This will still allow you to install a deep layer of insulation.
New Property or Old Property?
In a new property with a well-ventilated loft, using recycled polyester insulation will be very effective. Recycled polyester insulation is a great way to use recycled single use plastics. It’s also safe to handle and itch free.
If you have an older property or your loft ventilation is a bit limited, natural fibres might help. Sheep’s wool insulation, hemp or cellulose will work well. As well as being safe sustainable and healthy, natural fibres can help regulate humidity levels. It does this by absorbing moisture and holding it in a safe form. It’s then released it as air around it becomes less humid.
Insulating between rafters
When insulating between rafters in a pitched roof (e.g. loft conversion) you may have limited space to work with. You might think about lightweight insulation with a low k value. Also consider what sound reduction properties you will need. Adding denser sheep’s wool insulation between the rafters will help with this. The sheep’s wool will also give some thermal mass to the insulation that you won’t get with light weight materials. This will help reduce over heating in the summer.
Insulating under suspended ground floors
Insulating under suspended ground floors now popular. In this case it is very important to deal with draughts coming from under the floor. If you don’t the effectiveness of your under floor insulation will be reduced. Materials such as sheep’s wool or recycled polyester can be stuffed in the gaps around the edge of the floor. This will lower draughts that can go up the back of skirting. It also fits snuggly between floor joists creating a draught free layer. Installing a breather membrane above or below the floor joists will provide more draught proofing. You should ensure that air movement under the floor is maintained. If the floor joists are damp, you should deal with the source of damp before insulating.
Controlling moisture and humidity is very important when you insulate walls. That’s because it can be very hard for moisture to escape from a wall once it gets into the wall fabric. The right vapour control is vital. This will limit the amount of moisture able to enter the wall. It also provides a means of escape for any trapped moisture. Use a natural fibre insulation such as sheep’s wool with a well-installed moisture variable membrane. This can provide an effective option when insulating external walls from the inside.
In a nutshell, insulation does much more than prevent heat loss so give this some thought when you decide what’s right for you. If you choose the right insulation first time, you’ll never have to do it again. Choose good quality insulation and remember that over its life, insulating is never a costly investment.
Written by Mark Lynn
29th August 2019
Mark Lynn is MD of Eden Renewable Innovations Ltd and Vice Chairman of the ASBP
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