Better Buildings Act of 2013 - Amends the Energy Independence and Security Act of 2007 to require the Department of Energy's (DOE) Assistant Secretary of Energy Efficiency and Renewable Energy to study the feasibility of: (1) significantly improving energy efficiency in commercial buildings through the design and construction of separate spaces with high-performance energy efficiency measures, and (2) encouraging owners and tenants to implement such measures in separate spaces. Requires the Secretary to publish such study on DOE's website.

Requires the Administrator of the Environmental Protection Agency (EPA) and the Secretary of Energy to develop a voluntary Tenant Star program within the Energy Star program to recognize tenants in commercial buildings that voluntarily achieve high levels of energy efficiency in separate spaces. Requires DOE's Administrator of the Energy Information Administration to collect data on categories of building occupancy that consume significant quantities of energy and on other aspects of the property, building operation, or building occupancy determined to be relevant to lowering energy consumption. Prohibits the impact on climate change from being a factor in determining energy efficiency of commercial building tenants.