Will changes to the Building Regulations mean that gas boilers and conservatories will eventually disappear?

Unless you have unlimited wealth, or deeply incriminating evidence of misdeeds by the chair of your local authority planning committee, self build is best regarded as a process of compromise.

Your plot may seem ideal, but you won’t know all its secrets until the ground is broken. Your architect’s plans may delight you, but your local authority planning committee can reject them for, in your view, the flimsiest of reasons.

And your contractor - well, the contractor’s role is to bring your plans and dreams into the real world, which generally involves them telling you what is or isn’t possible and that it will cost you far more than you ever imagined.

But there is one aspect of self build which is relatively straightforward, and that is the Building Regulations (in Scotland, Building Standards). These are a set of technical requirements ensuring that your project is constructed in ways that are safe, secure and stable.

Your build will either comply with them or it won’t, in which case your plans must be revised or the offending item rebuilt. They’re administered by local authority Building Control departments or independent inspectors, both of whom make regular site visits to ensure compliance.

Over the years the regulations have steadily grown in scope to include areas like energy efficiency and improved access for the less able. But the changes due on June 15 this year are some of the most dramatic and far-reaching yet. Their main aim is to reduce carbon emissions for new homes by 30 per cent, en route to the government’s target of zero-energy homes by 2050.

So what are the main points and their likely implications for your build?

1. New minimum standards will apply for the energy efficiency of the fabric of a new build - in other words, the external shell. This means improved levels of insulation for external walls and doors, roof, floors, windows and any points of thermal bridging, such as where services penetrate the shell.

One example is the current maximum allowed U-value of a window dropping from 1.4 to 1.2 (U-values measure heat loss; the lower the better). But that figure now encompasses the window as a whole, including the frame and not just the centre pane of glazing. According to Joe Campion of Wigan-based Quadrant Building Control, this makes it much more likely that triple rather than double glazing will be required to meet the regulations.

2. Gas boilers will almost certainly disappear from new homes. The new regulations specify a maximum temperature of 55ºC for domestic heating, compared to the 75ºC common in radiator-based gas central heating systems. Low temperature systems need larger transmitters of heat – underfloor heating or enlarged radiators – to achieve normal levels of comfort.

Heat pumps, which are most efficient at lower temperatures, are the favoured alternative. They not only demand high levels of insulation and airtightness to be effective, they also need large hot water cylinders. These store the water heated when the heat pump is operating most efficiently, so a constant supply is guaranteed at the most economical cost.

Gas boilers, incidentally, aren’t specifically banned, but if you do fit one you will need to ensure your heating system can cope with a move to a low temperature system.

3. Insulation will also be improved for hot water and heating systems. Previously pipework only needed to be insulated if it entered uninsulated space inside the house or passed outside the building. Now it must be insulated inside any internal void, including underfloor spaces and behind plasterboard.

Wastewater heat recovery systems will also become standard. These use the warm water from baths, showers and basins to preheat incoming cold water, typically by running it through copper piping encircling the waste pipe.

4. Overheating is tackled for the first time in a new regulations document which limits the amount of glazing, depending on the orientation of specific rooms and the available ventilation. This has particular implications for conservatories open to the rest of the home and also for large areas of glazing, such as bifold and wall-wide sliding glass doors.

The document does provide a ‘dynamic thermal modelling method’ for calculating ways to avoid overheating and remove excess heat. Applying it, however, is likely to require expert help, which will increase costs.

One likely consequence is that roof overhangs, external shutters on windows, brise soleils and pergolas will grow more popular as extremely hot summers become more common.

5. If the new regulations sound too onerous you can avoid them by submitting your Building Regulations application before June 2022 and starting work on site before June 2023. In that case the current regulations will apply.

But any savings are likely to be swallowed by the additional fuel costs you will incur, not to mention alterations you may have to make in future, either when you extend your property or come to sell it in a more energy-conscious market.