Zero Carbon Misconceptions (and the Point of Saturation)

Paul Bainbridge, Technical Director

Paul’s Greenprints   

No, it’s not the latest Harry Potter book.

Zero Carbon Misconceptions (and the Point of Saturation) is our follow-on blog from our piece on Regulating Zero Carbon.

When discussing the quest for Carbon Zero in Construction (Zero Carbon Homes, in other words), dispelling myths and misconceptions will always be at the forefront of what the great team here at The FES Group do for our clients and customers. One of those misconceptions – as we touched on last time – is that powering homes via electricity is a more efficient alternative to using gas (boilers) when heating new homes under the target to become Zero Carbon Ready. Well, we said it last time, and we’ll say it again – this really isn’t the case. In truth, electric radiators, electric immersion water heaters, and electric panel heaters are all in the main (if you’ll forgive the pun) incredibly inefficient (at least as far as modelling is concerned), and so when we talk about coming away from gas and moving towards electricity to make our homes Zero Carbon Ready, what’s really meant is that we should be using Air Source Heat Pumps/Heat Pump Technology in our plans. These things merely happen to be powered by electricity – note the difference.

Everything we continue to write about in this recent stash of blogs relates to the Government’s vision of how Zero Carbon is going to be achieved. The intention is for boilers (gas, hydrogen, hybrid, etc) to be ‘banned’, but even that sentiment isn’t really quite accurate. Theoretically, developers could still plan for and install a gas boiler in a new home under the new regulations, but in order to meet the requirements and standards that drive us towards becoming Zero Carbon Ready, there’s simply no practical way for gas to feature as a fuel for any new home or building. And so, gas boilers aren’t exactly outlawed as we move to the future, but they’re pretty much wholly impractical, at the very least.

Under the New Homes & Buildings Standard, new homes and buildings (funnily enough) need to be Zero Carbon Ready when complying with the new Part L (2025), which means no retro-fitting would be required to take place after construction is complete. In essence, getting things right the first time – with no misunderstandings around meaning – is going to be key for developers and their design teams. We’ll always be here to advise should there ever be any questions anyone has, but for now, do keep reading and taking note of our blogs. We really do know what we’re talking about!

Just as we’re already witnessing in the world of motoring – with our cars moving to all-electric models – our homes will soon (certainly under publication of the new regulations) be following the same path. For reasons of cost, efficiency, and compliance with Zero Carbon aims, we’re looking at an all-electric future in construction, with heating and lighting being fully mains-powered (and therefore 100% derived from Zero Carbon energy sources).

This is the theory, at least.

What happens next – again, in theory – is that the construction industry then off-set any energy use via micro-generation on a local level; predominantly via the implementation of PV. The aim is that we’ll reach the point of each home or building generating anywhere between 50% and 70% of the energy that’s needed and used to keep it up and running. This is all sounding very positive for both pocket and planet, we’re sure you’ll agree.

A note to add is that this all similarly applies to apartment blocks, where mains-powered Heat Pump Technology is delivered through community fed systems, networks, or districts – or simply site by site. What we’re doing a lot of right now at The FES Group, is making sure our clients know that should they want to design and build an apartment block as part of their development, they’ll need to factor in the placement of a plant room to house enough Air Source Heat Pumps for each dwelling. And the higher your high-rise rises, the more space you’ll need to accommodate. It can become tricky to find space, and costly to implement it in the first place – be warned!

And on the subject of things being costly to implement, let’s turn our attentions – as promised in the title – to the Point of Saturation.

What do we mean by this phrase that sounds like it could easily pass as the title for the latest installation in the Mission Impossible film franchise? Simple. The Point of Saturation is the point in the design and construction of new homes and buildings that means there’s no benefit against the cost incurred. In other words, when it comes to making homes more energy efficient – if not entirely Zero Carbon Ready – it’s the point where making a change costs more than the savings that would be generated in return over a reasonable period of time.

We’ve concentrated until this point on heating systems, but the Point of Saturation more closely affects the fabric and footprint of our homes. In other words, the materials our buildings are constructed from. Think walls, floors, roofs, windows, and doors.

The Building Fabric System of new homes has had a question mark hanging over it during consultations for the latest building regulations under the Future Homes & Buildings Standard. The thought is that there’ll be nothing much done to insist on significant improvements of Building Fabric Systems between Part L (2021) and Part L (2025), because we may very well have already hit the Point of Saturation. In layman’s terms, the amount of money it would cost to improve something (eg, cavity insulation in the walls), would cost so much that it would outweigh and negate any energy saving it was proposed to make in the first place over a set period of time.

Let’s look at an example. Let’s say you want to insulate – or further insulate – your walls beyond the set current industry standard (U-value below 0.24 W/m²K ish) because you feel the fabric will hold the heat better and therefore reduce bills for your customers, making the homes more attractive to buy. That’s great, but in spending say £10k on these efforts, the saving in return might only be £1k over the next 25 years. Worth it? Obviously not. It’s a false economy, and therefore, nobody’s going to put much energy (so to speak) into exploring it.

Windows in particular don’t offer enough of a ‘return’, and are therefore among the quickest of the fabrics to hit that Point of Saturation. Triple glazed instead of double… is it worth it?

The great thing about the Point of Saturation (despite it sounding particularly soul-less as a phrase), is that there’s no need for developers to start significantly redesigning their house type designs for their new sites. Essentially, the existing Fabric Specifications should be able to carry over to the new regulations, with some standards being tightened up in areas such as Air Testing, for example. This should at least be the case until the industry starts doing some work around the types of materials we work with in the future (for cost purposes, as well as the pursuit of being a little kinder to the planet in the process).

This is all good for our clients to know and to get on board with, because making dwellings wider (for example) on a floor plan, is obviously going to have a knock-on effect on available space. For example – if, as a developer, you’ve got 20 houses on your row, and each one of them suddenly needs to be 100mm wider to account for added insulation, suddenly the house at the end of the row (sounds like a horror film) hasn’t got a pathway – and you really don’t want to pith anyone off with that one.

It’s been suggested in Consultation that the footprints of houses won’t get bigger thanks to Fabric Specification changes, but we know this has still been on our clients’ minds – hence the reason for us writing about it for you.

As an industry, it would seem we’ve hit a Point of Saturation where the price per performance is no longer cost effective. Should you fancy a bit of further reading around this (and why wouldn’t you), this is all detailed within the Impact Assessment released alongside the Future Homes & Building Standards Consultation Documents.

And so, in summary, Fabric Specifications should stay roughly the same, with amendments in the regulations instead made for Air Source Heat Pumps (Heat Pump Tech), Waste-Water Heat Recovery, Ventilation, Air Testing, and… PV. But we’ll explore that in our next blog.

It’s that age-old question, really…

To PV, or not PV?