Tim Doherty shares what you need to know to get this crucial element of your new home right

F inalising your new self build’s central heating system is an important decision that needs to be made at the start of your project. But who chooses what’s needed, what are the options and where should you start? Here’s what you need to know.

Fabric-first approach

The type and performance of your building envelope is crucial to the design of your heating system. You’ll probably have heard of the fabric-first approach, where building designers talk about extra grades and higher specifications of insulation and how airtight their detailing is proven to be. This really does matter, as reducing heat loss and air leakage should be one of the core design criteria for your space heating system.

A good example is the philosophy behind Passivhaus – another term you’re likely to have came across. The concept is to make the superstructure so airtight and well insulated that conventional heating systems are not required. In these buildings, everything from human activity to cooking and lighting contribute towards your space heating. There are accredited Passivhaus buildings in the UK and their owners are rightly very proud of the unbelievably low running costs they benefit from, so we know through published measurement that these principles really do work.

Mechanical ventilation & heat recovery

All buildings need ventilation. Stale air must be replaced with a fresh supply, plus smells, pollutants and moisture removed, too. In new builds we are required to create forced, controllable draught in our homes, the amount of which is dependent upon occupant numbers and household activity. The best way of achieving this, and central to the design of any energy efficient build, is the installation of a whole house mechanical heat recovery and ventilation (MVHR) system. In these setups, the warmth in the outgoing stale air is recovered and transferred into the fresh, cooler incoming supply so little additional heating is required. In very simplistic terms, if your MVHR is operating at 75% efficiency and your space heating is set to 20°C, on a cold day (say 2-3°C), the new incoming air will be circulated at circa 15/16°C