Our 2021 Diversified Property Investments business activity continued apace. We realised several profitable exits which contributed to strong social and environmental benefit. It was a year in which we further diversified our property portfolio and made good progress in developing our strategies, including a formal responsible investment policy and a first full carbon emissions estimate for our business (scopes 1,2 and 3) to help plan our route to operational net zero carbon.
A major success was the sale of our West Midlands Interchange interest, after we secured planning permission to create a nationally strategic 8 million sq ft rail-served infrastructure centre in the UK. The ability to secure a commercially viable planning consent was binary, with the investment proving to have been high-risk, high-reward.
Its subsequent sale to specialist developers last year, enabled us to achieve a multiple on our investment over four years, while creating a scheme that will reduce long-term carbon emissions by facilitating the transport of more goods by rail, instead of by road. The completed scheme will also create more than 8,500 jobs and contribute over £680m a year to the UK economy.
Separately we sold a 10% share of Sonae Sierra, the Portuguese multinational property company and real estate services provider, to Sonae SGPS, the majority shareholder. The sale means that we retain a 20% interest in the company which is benefiting from the easing of Covid restrictions across its markets and which continues to expand its activities beyond its core shopping centre holdings, guided by its high-quality management with whom we hold a relationship that spans over 20 years.
In 2021, we made good progress in our joint venture with MedProperties, a Dallas-based healthcare real estate specialist, including the acquisition of a brand new, highly specialised inpatient rehabilitation facility for patients, including those who have suffered from strokes, severe brain and spinal cord injuries. After six months of its opening, this new facility reached full capacity, demonstrating the huge local need.
In Australia, we committed AUS$100m of equity to six new assets with Gateway Capital, who acquire and add value to industrial and logistics properties in Australia; and in the US, we invested US$4m alongside our Greensoil PropTech partners to back a Californian-based domestic smart energy storage system. In Brazil, our student accommodation joint venture with VBI Real Estate continued to expand, opening two new sites last year with a further two under development.
We look further into 2022 with several new transactions already in the pipeline, and a commitment expressed in our revised overall property strategy to significantly expand our investment activity. Our expectation is that we will need to carefully navigate fast changing and uncertain property markets if we are to uncover exciting opportunities with great partners that can meet both our commercial objectives and deliver the social and environmental benefit we expect our activities to create.