We changed our roof and cut CO2 emissions

Nice savings! Tho no ingenuity is needed to calculate them as there is actually an established process used in the energy saving business. It uses &quot;degree days&quot; that are derived from temperature measurements, rather than using temperature measurements directly.<p>Degree days work better in regression as, assuming the correct base temperature is chosen&#x2F;calculated, heating degree days are directly proportional to heating energy consumption (including being zero when it is warm enough that no heating is needed) and cooling degree days are directly proportional to cooling energy consumption.<p>More info and data here: <a href="https:&#x2F;&#x2F;www.degreedays.net" rel="nofollow">https:&#x2F;&#x2F;www.degreedays.net</a><p>including an article explaining the process typically used for before&#x2F;after calculations:<p><a href="https:&#x2F;&#x2F;www.degreedays.net&#x2F;calculate-energy-savings" rel="nofollow">https:&#x2F;&#x2F;www.degreedays.net&#x2F;calculate-energy-savings</a><p>Disclaimer: I work for the company behind that site, and yeah I know it looks a bit dated :D

One thing people are not so much aware about other than insulation is air sealing. A tiny gap that may seem like nothing is in fact very bad. Take windows notoriously bad for heat and air leaks. A small seam along a window that isn&#x27;t locked (it should be) could be the equivalent of having a 1cm hole in the wall.<p>If insulated well and air sealed a home would lose very little energy. But also you&#x27;d need a good air handling system to move and refresh the air.

Did I miss the amortization of the CO2 emitted during the change?

One thing to point out is that yes, saving CO2 is grand, but this doesn&#x27;t sell just how much more _comfortable_ decent insulation makes things.<p>I live in a &#x27;30s UK semi detached. It had an air brick , a blocked up fire place and blown double glazing in each room. (barring two that were replaced)<p>We had to re-render the place, as it was starting to fall off at the front, and the back was scarred from unfinished renovations.<p>We replaced the double glazing with triple (it was cheaper than double glazing at the time, so a no brainer. has a u-value of about 1.0)<p>We also put 90mm of external wall insulation round the outside as part of the re-render. This cost an extra £4k compared to just a normal re-render.<p>before the insulation, in summer the front room would reach 37 degrees C with the blinds down, and in winter with a 5kw wood burner and central heating on full we&#x27;d reach about 18 degrees c when outside was either windy or -3c<p>Now in summer the hottest we&#x27;ve had it is about 29, with the blinds open. In winter we reach 20 within 30 minutes of the heating coming on. ( no need for the wood burner)

1.5 tons in 6 months.<p>this period is important. otherwise number doesn&#x27;t mean much to me.

Insolation is an extremely effective way to save energy.<p>But with cold bridges and such it can be a little complicated to get right.

Is triple glazing still not a thing in most places? It&#x27;s become pretty much standard here in Romania in everything but the cheapest windows.

Interesting.<p>It would have been nice to add a calculation of the energy required and CO2 produced to manufacture, transport and install that roof.<p>I feel this is an important metric that is generally ignored in these conversations. And yet, it is crucially important in order to determine the true outcome.<p>That said, I understand just how complex this input can be to obtain. You can’t reduce it to a number per window. That’s not how it works.<p>In order for someone to produce those ten (or whatever) windows somewhere in the order of twenty companies must exist and operate constantly. Aluminum mining and processing, steel production, extruders, paint&#x2F;coatings, chemicals, oil&#x2F;petroleum, fasteners, cardboard and foam packaging, forklifts, trucks, CNC machines, computers, etc.<p>The point is: These companies don’t exist just for the 42.5 minutes it took to assemble and pack the windows. In order to be able to buy ten windows, they have to exist whether or not someone is buying that model window or not. The energy required and CO2 produced comes from the combination of all of these factors. And, yes, this is hard to estimate. Yet the numbers are very far from zero.<p>It’s like saying you are going to go live in a tent on a small island to reduce CO2 emissions while ignoring the car ride, flight and ferry that get you there and the freighter that delivered your possessions.

This is great.<p>I&#x27;d also like to point out that with switching from gas to heat pump heating&#x2F;cooling you&#x27;d probably save even more on your bills and have 0 on-site carbon emissions and likely 0 off-site emissions as your electricity starts coming from non-carbon sources. Heat pumps are around 3x more efficient than the most efficient gas heating because they&#x27;re just moving heat around, not creating heat.<p>As Saul Griffith says[0], &quot;You can&#x27;t &#x27;efficiency&#x27; your way to 0&quot; (meaning 0 emissions, which is what we need).<p>Efficiency is a great win for our bills and cutting some emissions but even if every building made their current systems more efficient, we&#x27;d still be on track for over 1.5C of warming. What we need is transformation, and most of that to electric heating&#x2F;cooling&#x2F;transport&#x2F;cooking. And we need it fast, all across the residential and commercial economies in the next 2 decades with more in the next decade. It&#x27;s going to be a war-time-like effort. Thanks for getting it started!<p>[0] <a href="https:&#x2F;&#x2F;mitpress.mit.edu&#x2F;books&#x2F;electrify" rel="nofollow">https:&#x2F;&#x2F;mitpress.mit.edu&#x2F;books&#x2F;electrify</a>

They may be saving energy, but 17.2°C average temperature indoors is freezing.

nitpicking time :D<p>&gt; (assuming a 0.3g of CO2e per kWh<p>It&#x27;s kg there, not g.<p>And this number is for the electricity, gas is 0.203 kg per kWh.<p>If you are indeed heating with electricity, in france the electricity CO2 is almost always below 100g of CO2e per kWh.

It would have been interesting to also estimate how much CO2 would be reduced if instead of a glass roof they used a normal properly insulated roof. So we can see what is the CO2 cost of a stylish glass roof.<p>Note: I suggest using underfloor heating, it should be more efficient with a glass roof, because there is less hot air to raise to the top of the house.