Energy Conservationist Andrew worries about ceiling cracks in Grand Designs first-look

And during the process, Andrew becomes concerned that too much Earth is being applied to the top of the building, which could potentially lead to cracks in the ceiling, something which would spell disaster for the project.

As Kevin McCloud explains in the clip: "The tiniest crack in his ceiling could become a gaping chasm in the project, if it means replacing the roof."

"If I saw a crack right now I'd probably cry," Andrew explains as he nervously checks for damage. "In fact, there's no probably."

Andrew aims to heat the completed house all year round by storing the warmth of the summer sun into insulated earth banks over and around the house, and drawing the warmth back into the living spaces in winter.

But the pioneering construction soon appears to become an exercise in trial and error, as his initial design is vetoed as ‘unsafe’ by his structural engineer.

As a result, what began as a simple concept soon becomes a complicated feat of earthmoving and engineering, testing Andrew's small £300k budget to the limit.

Grand Design’s 21st series began at the start of January, with Kevin McCloud having presented over 200 episodes of the Channel 4 show since its 1999 debut.

To find out how Andrew gets on, tune into Grand Designs on Channel 4 tonight at 9pm. Catch up on All 4. Looking for something else to watch? Check out our TV Guide.