Hartman-Cox Architects is committed to sustainable practices and in particular the limitation of greenhouse gas emissions in three ways:

- designing buildings only in urban communities, 
- preserving the embodied energy of existing buildings, 
- designing energy efficient buildings.

Over half the work at Hartman-Cox Architects involves some component of preserving existing structures and/or adaptive reuse. These buildings contain "embodied energy", a significant amount of energy of all types required to construct the building initially. Retaining this energy by reusing the building means that that energy is saved, as is the energy required for demolition of the building if it were to be destroyed. 

For more than 30 years, Hartman-Cox Architects' buildings have been constructed entirely in urban and campus environments (ie, zero Greenfield sites). These are areas that have available utility infrastructure and redevelop our communities. Commuting time and emissions are reduced, no trees or agricultural land is destroyed, and public transportation is readily available. 

Investigating energy conscious design and planning is a matter of course for Hartman–Cox Architects. Developing new strategies, energy modeling and life cycle cost analyses that consider initial cost, energy, life span/replacement, and maintenance are fundamental to our practice. Site orientation, building envelope design, day–lighting, creative lighting and controls, and efficient mechanical systems are intuitive and constantly interwoven. 

While our primary goal at Hartman-Cox Architects is to reduce greenhouse gas emissions, we produce economical and sustainable buildings in many other ways; the LEED rating process, as established by the US Green Building Council, provides a framework for measurement and verification of sustainability. Most of our projects pursue certified LEED Silver or Gold status and a portion of our architectural staff are LEED Accredited Professionals with extensive experience on multiple sustainable projects. 

The studio environment at Hartman-Cox Architects is supportive of our mission to design sustainably. Two thirds of the employees use alternative means of transportation for commuting (metro, bus, walking, biking). Our office is in an early 19th century warehouse in Georgetown (embodied energy/ adaptive reuse), there is bicycle parking in the building and a shower facility. We use non-disposable dishware and have a full recycling program, high efficiency lighting with dimming controls, programmable thermostats and low flow fixtures.