Retired academics Judith and Barry Richards sold their home in Kent two years ago and decided to split their time visiting the US where they are from and where their son lives, and east London where Jeanine, their daughter, lives with her architect husband and three kids.

When the couple sold their home, they picked their favourite pieces of Georgian furniture and moved into a modest two-bedroom house at the back of Jeanine's garden. "We thought we would use the opportunity to see more of the children and grandchildren," Judith said.

Bernard built a Passive House for his in-laws which were placed in the garden of their home. He intentionally used this home design to make it green or eco-friendly and to apply his expertise in Tectonics, the architectural firm where he is working in London. It is spelled as 'Passivhaus,' which he considered a chance for him to apply his principles both as the client and the architect of the house he designed.

"I thought: 'I'm doing this building for myself, so it should be green.' What was important for me was that it was measurable. Passivhaus was the one that was the most constraining and nerdy," Bernard said.

He added, "What really sets this place apart is the marriage of Judith and Barry's homely style with the house's industrial finish."  So, he asked help from his consultant, Peter Ranken, from Accredited Passivhaus Design, in Passivhaus Institut in Germany.

In that same place, they need to send the data needed which contained the maximum of kilowatts the residents should consume in that house. He stated, "Peter is an architect by training, so he understood what I wanted to do. Passivhaus doesn't have rules - it just has number you have to achieve." This is how the 'Passivhaus' will be built.

"They say you cannot use more than 1,500 kilowatt hours [of energy] per year - and how you get there is up to you."

The couple decided to have the house in Passive design due to the shocking price rates for electric bills in Kent.

Judith explained, "I can't tell you what the energy bills in Kent were - but they were shocking. Here, they are modest [around 70 UK pounds a year]. It's very comfortable, it's a pleasant temperature, and there's a feeling of fresh air. I love huge windows."

The entire house measured 100 square meters with the planned two-storeys which will have lower-ground and upper-ground parts. They will also have study areas as well as kitchen just like any regular house. The pieces of furniture were retained in the house which matched the house's industrial finish.

"The furniture is more antique than I suppose younger people would have. But we're pleased that it fits in here," Judith stated.