Phoenix shipping containers used as housing and homeless shelters

A Phoenix company that transforms used shipping containers into solar-powered homes and offices has been named one of the most innovative housing solutions in the country.

State of play: The U.S. Department of Housing and Urban Development invited Steel + Spark to display its ADA-accessible "Sparkbox" on the National Mall in Washington next month as part of its Innovative Housing Showcase.

• Phoenix-based Cavco Homes, which designs manufactured homes from renewable materials, will also be displayed.

Zoom in: Sparkboxes range from 160 to 363 square feet of livable space and don't need to connect to electricity, so they can be installed and usable in a single day, says Steel + Spark co-owner Kathleen Santin

• They're powered 100% by the sun during the day and lithium batteries at night.

Why it matters: Steel + Spark sees them as a quick and environmentally friendly way to address Phoenix's housing shortage.

Between the lines: There are two Sparkbox models.

• One is a studio apartment made of two containers with a Murphy bed, kitchenette, living room and full bathroom. It starts at $218,000 and could be used as a mother-in-law suite or rental property in a backyard.
• The other is a smaller space made from a single container that could be an office or music studio. It starts at $81,000.
• Both have solar panels on the roof.

1 big flush: The larger Sparkbox has an incinerator toilet that burns waste. Santin promises it doesn't smell bad — just an occasional faint campfire smell outside during a flush.

• The toilets, manufactured in Norway, are popular in Europe. They save 2,000 gallons of water per person each year, per the company.

The latest: Two of each Sparkbox variety have been on display at a city of Phoenix-owned vacant lot since February through a partnership with the city and Arizona Department of Housing.

• After the HUD showcase, they will be donated to a local nonprofit for transitional housing for people experiencing homelessness.

What's next: Using shipping containers as non-congregate homeless shelters.

What's happening: The city of Phoenix awarded Steel + Spark $2.6 million in December for four "X-Wings" — a modified container project that will each contain 20 sleeping compartments.

How it works: The wings are made of four containers in an "X" configuration. Each container will have five rooms with a bed, desk and cubby.

• They have air conditioning and heat and don't need to connect to the grid, which makes them easy to move..
• The units don't have bathrooms or kitchens, so will need to be located near a building that does.

The intrigue: The X-Wings will be ready July 1 and were supposed to be deployed at the city's new homeless campus at 22nd Avenue and Lower Buckeye Road, but it is delayed and won't be ready until the end of the year at the earliest.

• Phoenix homeless solutions director Rachel Milne says the city doesn't currently have plans to install them elsewhere on a temporary basis.