Energy bills vs insulation

Home comfort, is it all about the money?

Our house is a 1970s half-in-the-roof type house, the upstairs is mostly timber frame and flat roofs, downstairs the construction is cavity wall… I’d say there’s next to no insulation. The heat goes out almost as quickly as we put it in, on the flip side – in the summer – it’s baking upstairs. The temperature downstairs is more stable from the thermal mass of the block walls.

I say “let’s insulate!”, yet we haven’t to date. We’d never recoup the financial outlay. We’ve replaced the boiler a few years back to increase efficiency but the fact remains the house leaks heat. Now with energy bills on the rise, it’s a discussion we’re having again. Here are four reasons to insulate:

1. Keeping warm

The house will be warmer, primarily insulating is about comfort. Yet, the reality is it won’t actually be warmer (unless we choose to crank up the thermostat), we’ll just be using less energy to keep it the same level of warm. Maybe psychologically I will “feel warmer”?

2. Using less energy

We’ll be using less energy to keep it warm because the heat losses are reduced. We’re going to improve the performance of the walls, roof and floor (not the floor in our case) by insulating – we’ll have better U-values. Granted we’re looking at a very simplified model here which doesn’t really consider air tightness or thermal bridging. Junctions are not your friend – there’s a reason Passivhaus design is easier with a box.

3. Saving money

Heat loss is equal to heat load meaning the less energy that escapes out the less energy you need to put in. And less energy in results in lower energy bills. It’s always about the money, at some level.

4. Overheating is mitigated

Summer comfort will be improved, this is an often overlooked benefit of insulating, think of insulation as a warm puffer jacket in the winter and more of a un-iced cool box in the summer. It’s not making your house colder, it’s just stopping the contents from melting. Overheating is becoming more problematic in the UK to extent that Part O of the Building Regulations is coming out this summer with regulation that will cover this topic. If you live in a “lightweight” house (i.e. one where the there’s no masonry to slowly absorb and release the heat) you’ll find the temperature fluctuations can be quite dramatic. Insulation plays an important role in stabilising that.

Don’t get me wrong, our house is not a single glazed, solid walled Edwardian house – the heat loss situation could be a lot worse. But I can’t help but think, that if we can afford to, sooner or later we should get on and insulate.

What your Conservatory is saying is “Replace me”!

Conservatory: lovely concept but far too hot in summer, too cold in winter. Terrible thermal performance is the number one reason to get rid of it, that’s what it’s trying to tell you! But take care not to replace it with an extension that is glazed to the extent that the same problems might persist.

Poor Performance

Designing a new extension to replace a conservatory is a brief I’m commonly presented with. The main reason cited for replacing it is always poor thermal performance, don’t get me wrong – conservatories have their place but they aren’t very functional for year round family living and if yours is a dumping ground for toys and garden paraphernalia, fear not – there are others out there just like you.

That said, there are some huge advantages in terms of light that come from a fully glazed room. And in replacing a conservatory it’s often the case that you’ll want to go for as much glass as you can, which could in turn perpetuate the same conditions. Fortunately, the Building Regulations have some criteria to help you avoid this in terms of amount of glazing that is permitted before you reach a tipping point. After which you’re required to mitigate your excess glass by “over insulating” other components to compensate, although this is more in relation to heat loss than solar gains.

There are lots of options including triple glazing and solar control coatings to help improve the performance of your glazing and the orientation of your building will be a key factor too. The angle of the sun comes into play somewhat in the UK where it’s low and weak in the winter (desirable) but high and hot in the summer (problematic). If your main elevation is south or west facing, you’ll need to consider the design quite carefully to avoid overheating in the summer months. Solar shading in the form of a roof overhang or vertical fin might be an appropriate solution.

Panorama Overdose

Rarely do people say “I want to replace my conservatory becayse I hate looking at my garden”. But it’s worth considering, do you want to look out on all of your garden or just the best bits?

Frame a view of something worthwhile, mask out the ugly bits. Yes, the apple blossom is nice but do you want to look out at your knickers on the washing line when you’re sat on the sofa… when your friends have popped round to admire your lovely new extension? Maybe not.

It’s also worth considering that floor to ceiling glass can play havoc with your furniture layout, see also Is Open Plan Always The Answer? where it turns out walls have their place.