It's a fair question and one we're hearing more and more.
Whether you're working from home, upgrading a single room, or trying to make a garden office usable all year-round, it's understandable to want comfort without blowing the budget.
But as ever, the answer depends on your space, your habits and what "cheap" really means to you.
First: What do we mean by cheapest?
Are we talking about:
Cheapest to install upfront?
Cheapest to run month-to-month?
Cheapest over the life of the system?
A basic fan heater might cost £20 from your local DIY store, but could cost several hundred pounds per year to run. In contrast, an efficient electric system may cost more upfront, but use far less electricity long-term.