Housing minister Sajid Javid always knew his job would be a tough one. The nation's lack of affordable housing is an issue that appears to need a seismic shift in policy.

Indeed, Mr Javid was recently urged by a respected think-tank to build more houses - a lot more. According to the independent Joseph Rowntree Foundation (JRF), England alone needs to build 600 new low-cost homes every week.

Under current plans, the government intends to build just 100 new affordable homes a week.

The JRF and others says a long-awaited “wide-ranging, top-to-bottom review” of social housing should include a pledge to build 78,000 affordable homes each year. Aside from saving people from expensive and precarious rental contracts, analysts believe it could slash the nation’s housing benefit bill, which last year soared to £23.4bn.

The housing crisis continues to gain more column inches, not least because the Archbishop of Canterbury recently decried the lack of affordable housing and the UK's generally "dysfunctional" housing market. His new book Reimagining Britain: Foundations for Hope, is equally critical of the culture of buying second or even third homes.

So the pressure is certainly building on Mr Javid. However, he has an idea to solve the crisis - or at least assuage it: ‘upfill’ old buildings with new accommodation.

What is upfilling?

Upfilling is the process of adding new levels of accommodation to existing buildings.

Mr Javid said: "The answer to building new homes isn’t always an empty plot, or developing on a derelict site. We need to be more creative and make more effective use of the space we already have available. That’s why we are looking to strengthen planning rules to encourage developers to be more innovative and look at opportunities to build upwards where possible when delivering the homes the country needs."

"Very fancy penthouses"?

For a country with strict planning laws, it would be a big step-change. ApexAirspace believes 200,000 new homes could be built in London alone using this process.

But others are less impressed by the idea. Treehugger's Lloyd Alter described a development he worked on in which a new level of homes was added to an existing building: "Being penthouses with great views and higher ceilings, they were the most expensive units in the whole complex. This will likely always be the case; it is likely that Housing Secretary Sajid Javid has just created some very fancy penthouses."

However, Alter thinks the idea might work if new communities were built on "supermarkets and stores with big flat roofs". He believes that approach could "open up all kinds of opportunities."

Time will tell if such a scheme is put into action and if will address the nation's ongoing affordable housing problems.