How to plan a forever home today. 

My parents built their ‘forever’ home in the early 1950s in the wilds of Essex – well, Romford, but let’s not quibble. 

Its walls were single-leaf uninsulated brickwork, the windows galvanised steel frames, with single glazing that streamed with condensation after a cold night, and the heating a mix of coal and gas fires and the odd electric bar heater. 

By modern standards it was spartan. But my parents loved it and, though they embraced central heating in the 1970s, were content to leave everything else pretty much as it was.

Duplicating such lifelong satisfaction would be a tough call today. We’re beset by global warming, ever-rising fuel costs and constantly changing government directives intended to make the UK zero carbon by 2050. Building to last in such uncertain circumstances seems a big gamble. So here are seven thoughts on lowering the odds on achieving a successful ‘forever’ build.

1. Put fabric first

This means prioritising the shell of a house over all other aspects. In other words, specify high levels of insulation in the external walls, roof and ground floor, including doors and windows, and ensure high levels of airtightness. Gaps in insulation as small as a few millimetres can halve its effectiveness. As well as eliminating draughts, this minimises both heat loss in cold weather and unwanted heat in summer. It also reduces the requirement for heating or cooling, however they’re provided. But there are three major catches.

2. Eliminate thermal bridges

A thermal bridge is where part of a house’s construction links interior and exterior, creating a break in the insulation and allowing heat to leak. Examples are a floor joist penetrating a cavity wall where there is a gap in the cavity insulation, or a steel lintel above a window, bridging an otherwise insulated cavity. As the level of insulation increases even small thermal bridges – such as the steel ties that hold a cavity wall together – can make a significant difference. 

3. Provide adequate ventilation 

A well-insulated, airtight house will retain heat, but also moisture from washing, cooking and breathing, as well as any pollutants from new carpeting or furniture. Currently the most comprehensive means of ventilation is a mechanical whole-house ventilation system. A slow-running fan, usually sited in the attic, continuously draws warm, moist air from the kitchen and bathrooms and expels it outside, while simultaneously drawing in fresh air and distributing it throughout the living areas. The central fan is often combined with a heat exchanger, which can extract much of the warmth from exiting air and use it to pre-heat the incoming air. The main drawback to the system is the extensive ducting it requires. Each duct is typically around 100mm in diameter, allowing it to be concealed within floor and ceiling joists. 

4. Choose construction method carefully

In principle it should make no difference how you build your home as long as it follows the measures outlined above. In practice, however, traditional brick and block, the UK’s most common method of housebuilding, can present practical difficulties. Since the bricks and blocks are laid by hand – often several – consistency of work can’t always be guaranteed. ‘Snots’ of mortar can drop onto wall ties, creating thermal bridges. Cutting then aligning dozens of rigid insulation boards to avoid the smallest gap is exceptionally demanding.

This isn’t to say well-insulated, airtight homes can’t be built in this way, and a number have been, but in general modular or prefabricated forms of construction, produced under controlled conditions, are better suited to this more precise method of building.

5. Maximise heating options

Given the government’s various zero-carbon pledges, guessing which heating system will be the best long-term investment is tricky. Will it be the heat pump, with 600,000 being installed every year by 2028, according to Boris’s recent pledge? A modified gas boiler running on hydrogen rather than natural gas? A natural gas/heat pump hybrid, designed to use whichever is cheapest at any given moment?  Or a micro-CHP (combined heat and power) boiler, a conventional boiler which also produces electricity? 

Fortunately, all of these can be used with a standard radiator system as well as underfloor heating (UFH). UFH, however, produces comfortable warmth at the relatively low temperatures heat pumps generate most efficiently. Compared to a radiator system, it’s also virtually maintenance free. Unfortunately, all of these alternatives to the standard condensing gas boiler are either experimental, hard to obtain or up to four times as expensive.  

6. Consider ‘bolt-on’ energy sources

If you have a south- or near-south-facing unshaded roof, solar thermal panels can produce much of your domestic hot water in summer. You’ll need a hot water cylinder with a dedicated solar heating coil, preferably as large as you can accommodate to store as much of the heat as possible. 

Rooftop photovoltaic (PV) panels can supplement your electricity needs – especially if you wait for a sunny day to use a washing machine or dishwasher or charge your electric car. PV will also earn you payments through the government’s Renewable Heat Incentive, though that may not last. On the other hand, solar panels continue to fall in price and rise in efficiency, so it might be sensible to wait.

7. Make your interiors flexible

Built-in sliding or folding partitions will allow you to maximise your living space for social or family occasions, or close off areas for work, children’s play areas, guest accommodation or just privacy. This will be cheaper and less disruptive to do at the planning stage rather than later in the life of your home. If you have sufficient space, consider broad hallways and corridors, too – all the better to accommodate buggies, children’s bikes, grandparents’ wheelchairs, furniture and kitchen worktops (even my parents upgraded theirs).

Janaury 2021