s.ky blue information

The Solar Decathlon is a project of the U.S. Department of Energy (DOE) in partnership with DOE's National Renewable Energy Laboratory.



Engineering: 77.000 out of 100 possible points


The houses are marvels of modern engineering, and this contest "checks under the hood." A jury of professional engineers evaluates each house for functionality, efficiency, innovation, and reliability. It considers:

  • Functionality—Will the home's energy systems function as intended?
  • Efficiency—Relative to conventional systems, how much energy will the house's systems save over the course of an entire year?
  • Innovation—Were any unique approaches used to solve design challenges? Do the proposed innovations have true market potential?
  • Reliability—How long are the systems expected to operate at a high level of performance? How much maintenance is required to keep them operating at a high level?


s.ky blue engineering


The University of Kentucky s.ky blue project provides an infrastructure designed to minimize energy consumption and supply necessary energy from an integrated system. This system efficiently collects, stores, and supplies the solar energy through highly efficient photovoltaic (PV) and solar thermal systems. The s.ky blue project is equipped with:

  • high efficiency appliances and lighting systems
  • multiple heat pumps and thermal storage tanks
  • piping systems for multiple modes of operation
  • an intelligent control system that selects the optimal method of operation based upon the local weather forecast.


These innovations provide an efficient, comfortable, adaptable, and convenient living environment that empowers its occupants to live “light” on the land.


The structure of the house is composed of structural steel elements designed for efficient transport as one complete, stand-alone unit ready for rapid on-site deployment. The structural floor beams are supported by four connection points. The house’s structural members are designed to minimize deflection while being transported and provide external lifting points. These external lifting points make it easier to put the house on the National Mall by eliminating the need for a crane during construction and are used with jacks to load and unload the house once it arrives at the site.

The integrated PV roof rack can be easily tilted with large integrated screw actuators to provide seasonal adaptation and maximum solar energy collection. This rack is shipped at 0 degrees for flat transport but can adjust to track the sun and optimize solar collection.



Communication among the systems’ components, their environment, and their users is provided by the control system. The integration of the systems offers opportunities to optimize the energy collected in response to changing weather conditions and selects the method of operation to use the energy most efficiently to provide comfort and convenience for the occupants.

An Automated Weather Adaptive Response Energy control system (AWARE) is being developed at the University of Kentucky to enhance the control system. This program receives zip-code-specific short term (24 - 72 hours) weather forecasts on a three hour interval, evaluates (using an energy model) the various energy storage (or use) options available in the building, considers all the possible operation methods for the next 24 hour period, and selects the optimal energy path.

The method, which minimizes the total energy consumption, is then implemented for the following three hours. The weather-AWARE system manages the HVAC systems, the solar thermal system, and a series of pumps connected to thermal storage tanks to provide heating, cooling, and ventilation in the most efficient manner.

The control system’s computer interface allows the user to view and analyze their energy consumption. It displays the circuits and items consuming energy to promote awareness and alert the occupants of practices that waste energy so they can partner with their home in the conservation effort.


Electrical (PV)

The house’s photovoltaic system (PV) is designed to produce at least as much energy as the house consumes during a year. The house will also be connected to the power grid with the ability to withdraw and deposit electricity.

In periods of high PV generation, the house can sell power to the grid. In periods of low PV performance, the house can purchase power from the grid. Over the period of a year, the house is designed to produce at least as much energy as it consumes, “net zero” energy usage.

The power generation for the house will be realized using two PV arrays – an 11kW single axis-tracking roof array and a 2.2kW building-integrated array on the south façade. These two arrays supply DC current to four inverters that turn the DC current into AC current to be used by the house’s systems and appliances.


HVAC System

The house’s heating and ventilation system uses a high-efficiency reverse cycle chiller coupled with a small thermal storage tank to provide hot water for floor heating and cold water for air conditioning and dehumidification. The reverse cycle chiller is an air to water heat pump, which can transfer heat from, or to the connected thermal storage tank by exhausting heat to the outside air or collecting heat from it.

The house is separated into three radiant heating zones and two cooling zones based on the occupancy and usage. Due to the space constraints associated with the efficient nature of the house design, a small ductless system is used for cooling and a concealed radiant floor system is used for heating. Two air handlers carry the cooling load - dividing the load increases efficiency and reduces latent load recovery time.