Andrew Himes is Director of Collective Impact for the Carbon Leadership Forum. Over the past several years in the building industry, collective decarbonization efforts have accelerated dramatically. Collective impact initiatives involving hundreds of companies and organizations from every part of the sector have inspired and catalyzed systemic change. These initiatives span sectors and disciplines, from building designers to contractors, material manufacturers to policy makers and industry associations. This is a great time to review the essential conditions for collective impact, sum up key lessons from our movement, and celebrate and apply what we've learned.