Allen Center

Sustainability Statistics


  • The project redevelops the underutilized outdoor space at the base of Allen Center, a 1970’s office complex in downtown Houston.
  • The space was made more accessible through the creation of various outdoor spaces.


  • 155 trees were planted, including overcup oak, allee elm and Chinese pistache.
  • 63 trees were saved.
  • Native and adaptive plant types were used, including sandi-leaf fig, iris, and Japanese yew.
  • The project minimizes pesticide and fertilizer use.
  • Mycorrhizal fungi was implemented in the soil mix to provide increased water and nutrient absorption for the planting. In turn the planting provides the fungi with necessary carbohydrates.
  • Plants are allowed to go to seed/flower life.
  • The project avoids annual planting.


  • 48% of outdoor surfaces are permeable.
  • The site design mitigates runoff.
  • Trees have the potential for intercepting 109,000 gallons of water which is the equivalent to the water usage for 1,090 American residents for one day. *

Carbon, Energy + Air

  • The trees sequester 26,160 pounds of carbon annually, which offsets driving 35,586 miles in an average car. **
  • The trees reduce the temperature of the plaza up to 10 degrees Fahrenheit.
  • During construction, pollutants were controlled and retained.
  • Exposure to environmental tobacco smoke was minimized through designated smoke-free zones and prohibited smoking on-site.


  • The design creates a pedestrian space in the predominantly concrete environment of downtown. The trees give the space a human scale, while offering the utilitarian benefit of shade for cooling.
  • The project supports alternative modes of transportation, with a bus stop at the edge of the site and bike parking.
  • The project provides optimum site accessibility, safety, and wayfinding through added signage.

* The tree average for water interception is 500 gallons. American’s use an average of 100 gallons of water per day (EPA’s water trivia facts)

**120 pounds of CO2 per tree annually (This number is based on an average from the National Tree Benefits Calculator) One car produces an average of 8,320 pounds of CO2 per year. (The Code of Federal Regulations - 40 CFR 600.113)

Allen Center

What once was a lifeless courtyard shared between One, Two, and Three Allen Center, The ACRE, has now been revitalized into a green oasis. The ACRE involved the removal of a second-level sky bridge and the large earth berm under it, which opened up the view to people walking along Smith Street and reconfigured the area into a publicly-accessible space for active and passive recreation. The open space also includes various small and large programmed spaces to accommodate events, art installations, performances, movies and concerts.

The landscape features a thoughtful botanical experience, highlighted by five distinct planting areas with a unique and striking combination of color and texture from 12 vibrant and adaptive plant species. Over half of the project is located above a below-ground parking structure, with no planting depth. Architectural planting mounds that slope at different angles were used to further define the exterior spaces. 

When designing The ACRE, OJB accounted for environmental sustainability, saving trees and adding additional native and adaptive tree species to provide generous shade to the site. The promenade surrounding the lawn uses light grey colored pavers, which reduce solar energy retention and minimize the impact on microclimates and habitats.


Location: Houston, TX
Team: Morrison Dilworth + Walls, D.E. Harvey Builders
Photo Credit: Brookfield, Peter Molick