Extension to rear of terraced house. The rear of the house was remodelled to form a new ensuite bedroom and new, much larger, kitchen area and outdoor patio seating area.
The real decision is whether you feel the additional expense, normally around 8-10% of the build cost, is worth it to have the most comfortable house you’ll ever own that requires virtually no heating.
In the UK the average 85m2 home spends almost £600 a year on heating and around £1350 on energy as a whole. It may seem incredible but reducing your heating bill to the cost of a cup of tea per day is entirely possible, saving many hundreds, even thousands of pounds per year for many.
A truly sustainable home would be one that is constructed from renewable materials that do not damage the environment and that operates with little or no impact on the environment. It would be in or near a town/city to minimise travel and would manage rain and waste water to reduce impact on sewers, etc.
The maintenance of your sustainable home will generally be little different to any other home so keep gutters/drains/gullies clear, prevent piles of leaves/earth from building up against your walls, etc.