City of Denver: Richard T. Castro Building


The Richard T. Castro Building was built in 1998 and encompasses approximately 307,000 square feet.  This general office and public service building houses over 800 employees and is primarily occupied by the City of Denver's Department of Human Services.  Their mission represents a commitment to working with community partners to provide resources and services to people in need making this a high visibility public facility serving large numbers of visitors each year.


The City of Denver first started considering energy efficiency upgrades to the building after collecting feedback from City facility managers. With its important place in the community and being one of the City’s largest buildings, the Castro Building was viewed as a top candidate for improvement. 



The building underwent comprehensive energy improvements beginning in 2012 which include sealing the building envelope, upgrading the building automation system, installing four new high efficiency boilers, and utilizing variable frequency drives on HVAC units to allow greater control and synchronization. The building also houses 30 kW of solar panels on its roof. 


The building is currently serving as a pilot site for interior LEDs as replacements for T8 fluorescent lamps, the City is using the pilot to gauge lighting levels and occupant feedback to determine how to roll out LED retrofit to other city buildings.  In addition, improvements have also been made to the parking garage serving the Castro Building. Energy savings to date have been significant, resulting in energy reductions of 36% at the Castro Building and 50% at the garage.

The complete list of energy efficiency improvements include the following measures:

  • Building envelope sealing
  • Installation of four high efficiency boilers
  • Installation of variable frequency drives on rooftop units, creating greater level of control and synchronization
  • Installation of frequency drives  on fan controls
  • New temperature sensors & damper actuators installed in the rooftop units
  • Building equipment commissioning
  • New Web Servers and computers installed onsite
  • Upgrade of BAS from Inet to Niagra, enabling better use of economizer features
  • Photo cell controls installed in parking structure
  • Currently conducting demonstration project replacing 160 T8 fluorescent 4’ lamps with LED lamps


The Castro building is also a participant in the 57 building Denver City Energy Project, an initiative aiming to unlock $1.3 billion in energy savings through targeted efforts to reduce climate-changing greenhouse gases from the energy used by commercial and multi-family buildings. Improving building energy efficiency will not only help reduce these emissions, but also protect Denver’s quality of life and strengthen the economy.


Its projected that investing an estimated $340 million in improved building energy efficiency would result in 4,000 local jobs and $1.3 billion in energy savings over 10 years.


Annual Energy Use

(Source EUI)
Baseline (2011)
218 kBtu/sq.ft
Actual (2013)
140 kBtu/sq.ft

Energy Savings:


Annual Energy Cost

Baseline (2011)
Actual (2013)

Cost Savings:


Sector Type

Local Government


Denver, Colorado

Project Size

307,000 Square Feet

Exterior of the Richard T. Castro Building
Exterior of the Richard T. Castro Building

Roof mounted 30kW solar array
Roof mounted 30kW solar array