Has my improved attic insulation actually reduced my carbon footprint? (A follow-up)

Last June I posted a blog about getting my attic insulation upgraded. You can read the full blog post here, but as a quick reminder, I upgraded from R30 to R62 in February 2019, and then created a model to predict my pre-upgrade gas consumption based on the weather.

My results from last summer suggested I’d seen a weather-corrected saving of around 4.5% of my natural gas consumption. Since then, I’ve been faithfully tracking my actual natural gas consumption and comparing it against my predicted results.

So, what have I found? Well, here’s the updated graph…

It’s the grey line you want to focus on. This is the cumulative sum of the difference between my predicted consumption and my actual consumption. You can see that at soon as the roof insulation was installed – halfway through the billing period 25 Jan to 28 Feb – the line dips down, meaning my actual consumption was less than it would normally have been.

What this shows is a total saving of 10.9 GJ over the last year. During the 12 months since my roof insulation was improved, I would previously have consumed 161.6 GJ of natural gas. However, I’ve actually only consumed 150.7 GJ. This is a 6.7% reduction that has not only has put money in my pocket, but has also resulted in me shaving 0.56 tonnes CO2e from my annual carbon footprint.

Simply put, this energy efficiency upgrade has made a measurable difference to my energy consumption and carbon emissions.

A more difficult task will be to decarbonize my heating system entirely. That’s something I’m planning on looking into this year, and I’ll share some thoughts on that in another blog post. In the meantime, any comments or questions are, as always, most welcome!