REI's buildings reflect our core purpose and provide employees the opportunity to engage with our communities, members and customers. Our built environment also accounts for one of our largest environmental impacts. We apply green building principles to address several of our environmental priorities, including energy efficiency, renewable energy and waste reduction.
Whether we are retrofitting an existing facility or building a new store from the ground up, our goal is to integrate sustainable design elements and for our facilities to be as energy efficient as possible. This approach also provides financial savings to the co-op.
To date, six REI facilities have received the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED) certification, totaling more than 690,000 square feet, or approximately 15 percent of REI's total square footage. We don't seek LEED certification for every REI building, but look to the LEED standards as guiding principles in design and construction.
In previous reports, we highlighted our prototype-design stores located in Boulder, Colo. and Round Rock, Texas. The experience, insights and learning we gained from those investments is paying off as we adopt attributes of those stores into our current standard package with new stores.
Features that are considered during the design process of every new retail store include energy-efficiency measures, low flow sinks, dual flush toilets, solar hot water, and passive solar design. Fixtures are manufactured from sustainable materials, Forest Stewardship Council (FSC)-certified woods, rapidly renewable fiber products, polished concrete and durable steel. Carpet tiles are made from recycled carpet and require no adhesive, making them easy to replace and 100 percent recyclable. All materials have no added formaldehyde, are low or zero VOC and can be recycled, refurbished or reused.
We continue to retrofit HVAC systems in our stores and we remain on track to eliminate units that use Freon (R22), a substance harmful to the ozone layer, by 2020 by replacing them with equipment that is more efficient and less impactful to the climate. The HVAC units are connected to an energy management system, which minimizes how often they must be on to control temperature fluctuations. These investments reduce our energy impacts and improve the comfort and indoor air quality of our stores for our employees and customers.
We intend to expand our on-site energy production through additional retail store solar systems in 2011. Currently, 11 stores feature solar power systems and collectively they produced over 1.1 million kWh in 2010. Our investment in solar panels makes great sense for the co-op because it reduces greenhouse gas emissions, reduces operating costs, and mitigates our exposure to volatile energy markets.
REI's store development division continues to evaluate our facility design and lighting as technology evolves, allowing us to reduce the energy impact of our stores. Combined with occupancy sensors and an energy management system, we are able to minimize the time each day that our lights must be on.