The Valdelasfuentes estate comprises 4,800 dwellings of which 80 percent are subsidised by tax reductions for families on low incomes. 300 of these are protected tenancies with options to purchase, and approximately half are intended for young people between the ages of 18 and 29.

All Valdelasfuentes properties have swimming pools, green areas, playgrounds and shared communal spaces. They are also equipped with modern environmental infrastructure, such as automated waste collection, a water saving system and solar panels which generate household hot water.

The vacuum system used throughout the housing estate has been operating since May 2001. From the 160 inlets via the 6,000-metre long underground pipe network, more than 4 tonnes of waste per day is carried in two separate fractions: residual and mixed packaging. The collection station does not look like an ordinary industrial structure, but by virtue of its solar panels, is one of the most unique buildings in the area.

Demands of energy efficiency

The Valdelasfuentes estate was completed at the end of 2007, with all the dwellings in the plan finished and all internal networks operating at full capacity. The Valdelasfuentes vacuum system contract which was put into operation by Envac in 2001 comprised of the delivery, commissioning and upkeep of the system.

One of the clauses that the Alcobendas Engineering Administration Office always insists on including in the tender documentation for operations and maintenance contracts is that companies must undertake not to exceed a certain maximum energy consumption, with fines to be paid if the limits are exceeded.

In 2008, Envac installed the Scada operating system to manage the installation. First the data gathered by Envac ever since the system was commissioned, was analysed to obtain an understanding of how energy efficiency could be improved without impairing the service level or other adverse consequences arising. Following a generic study lasting six months, when theoretical and practical data were compared, Envac made a number of changes to the installations’ programming parameters. The control program and the valve functioning software were updated and the operating time for collection was reduced.

The interest shown by the Alcobendas administration for low and sustainable energy consumption has encouraged Envac to embark upon a research and development project with the principal object of reducing the total energy consumption of the installations. The outcome of the project is the Energy Envac System® program, which Envac has patented. Thanks to this program, energy consumption reduced by an average of 20 percent.

Since the launch of the energy saving system in July 2008, it has been possible to enhance this result even more. In certain months such as December 2009, energy consumption was 38.5 percent lower compared with the same month the previous year.

166 kWh/ton in December 2008
102 kWh/ton in December 2009

When the installation was commissioned in 2001, Envac undertook to keep energy consumption low. Even when this was reached the company continued to investigate and optimise the variables which affect the operations of the system.