Zero Energy Certified


Originally known as the Darragh Building, this project was renovated in 2016 in order to house the headquarters of Entegrity, a building performance optimization consulting company.

The Darragh Building was designed by Noland Blass, Jr., of the Erhart, Eichenbaum, Rauch, & Blass firm in 1958 for the Darragh Company’s commercial and warehouse use and is located just east of downtown Little Rock, Arkansas within an emerging mixed-use district. The Darragh Building has several significant features which include: post and beam construction techniques, floor-to-ceiling glass walls and windows, extended floor and roof slabs that emphasize the building’s horizontal lines, a roof with no slope, a small atrium (which is now covered due to historic water damage), floating front steps, and exterior and interior concrete infill panels decorated with a stretched octagon and diamond three-dimensional pattern.  The existing building is in good condition considering its age and has had only minor updates over its lifetime. The building is listed on the National Register of Historic Places.

When Entegrity began to plan the retrofit of the 13,342 sf building which was occupied in January 2017, it was clear to the Partners that the building should be a high-performing, net-zero building, fit to house a company that offers efficiency, solar, and sustainability services to its clients. The entire renovation was designed and executed with sustainability and historic preservation in mind. Energy modelling was used to first determine strategies to reduce energy use as much as possible before adding in a rooftop solar array to bring the building to net zero. Energy efficiency strategies employed in this building include use of all-LED lighting, dynamic self-tinting glass, operable windows and doors for natural ventilation in the warmer months, and occupancy sensors. Other sustainability features of the building include the use of locally sourced materials as much as possible, preserving access to daylight and views, controllability of lighting comfort through the use of dynamic glass and self-tinting windows, highly efficient plumbing fixtures, and native landscaping. The project is certified LEED Platinum for New Construction/Major Renovation.

The building is owned by Sustainable Properties, LLC, and was designed, executed, and documented for ILFI Zero Energy certification by Entegrity.

Photo Courtesy of Entegrity
Certification StatusZero Energy Certified
Version of LBC31
LocationLittle Rock, AR, USA
Gross Building Area13,342 SF
Start of OccupancyJanuary 2017
Owner OccupiedYes
Occupancy TypeCommercial Building
Number of Occupants45
Photo Courtesy of Entegrity
OwnerSustainable Properties, LLC
Project ManagerEntegrity
ArchitectWER Architects and Planners
MEP EngineerECCI
Lighting DesignEntegrity
Interior DesignEntegrity
Photo Courtesy of Entegrity
Wall R valueR-1.4 Existing; R-12.3 New
Roof R valueR-4 Existing; R-30 New
Floor R value and section specificationNo Insulation
WindowsWindows are View Dynamic Glass – electrochromatic glazing that changes in tint in response to daylight brightness. SHGC varies between 0.39 when clear and 0.09 when fully tinted.
Air infiltration rate and sealing protocolConstructed addition with WRB-integrated sheathing and detailed transitions and penetrations with commercial sealants. Spot-sealed existing buildings with foam and caulk.
Photo Courtesy of Entegrity
Array Size48 kW
Panel Quantity155
Panel Type and BrandYL325-36b by YINGLI SOLAR
Inverter Quantity3
Inverter Type and LocationGrid tied PV inverter; non-isolated on south side of warehouse
Photo Courtesy of Entegrity

All lighting in the building is completely LED.  Lights are controlled by occupancy sensors in individual workspaces, as well as directly through an app on the occupant’s company phone.  Additional desk lighting is provided to individual desks with receptacle occupancy controls.


An occupant comfort survey is conducted at least once a year. The building operations manager ensures that controls and smart things are operating properly and responds to occupant feedback and complaints on a regular basis. The company reminds occupants of best practices through office-wide communications on an as-needed basis.


Entegrity performed design and construction phase commissioning to meet the requirements of LEED v2009 NC fundamental and enhanced commissioning. The systems that were commissioned include: HVAC, lighting controls, domestic hot water, photovoltaic system, and the View dynamic glass system. The main challenge that arose was ensuring that sufficient outside air was entering the space through one of the units. Ventilation was ensured by installing a booster fan in the intake ducts of the system.

Photo Courtesy of Entegrity