Guest Post: Ben Newell on Zero Energy Residential Optimization Software

This is Ben Newell from Equinox Built Environment Engineering ( writing a guest blog post about our ZEROs (Zero Energy Residential Optimization software) program now linked through the PHIUS Design Tools page. We are excited to offer this new design tool to the passive house community!

 ZEROs is an easy to use web-based energy prediction modeling program, but much more! Those experienced in designing and constructing super-performing buildings know that minimizing energy is not the sole factor in design decisions. Other considerations such as minimizing costs and maximizing health are just as important, if not more so. These design parameters are incorporated into the ZEROs model, giving you more control.

The goal of ZEROs was to develop a design tool that is very powerful and complex behind the computer screen, but with a simple interface that is easy to operate and very user friendly. We think we’ve accomplished that and plan to offer many tutorials that will help guide users in their own designs. Our centerpiece, Equinox House, was designed using ZEROs and the hundreds of thousands of data points we’ve collected since its completion validate the results. More about the design and construction of the net zero energy Equinox House can be found at

Equinox House, Urbana, IL

Modeling of both new and retrofit construction is possible. Main input parameters for the building envelope consist of the location, base house cost, wall, roof, and floor sizes, R values, and costs. The ground heat transfer is also included, an important factor dependent on the location. After defining the envelope, window parameters are entered for each side of the house consisting of area, U value, SHGC, and cost.

When the shell has been defined, characteristics of the building systems, energy, and comfort are selected. These relate to the efficiency of the conditioning systems, base load appliance energy, and the number of occupants, comfort set points, and fresh air ventilation. A solar module allows one to define a solar pv system to achieve net zero with the house design entered.

Once the parameters have been fully defined, running the model will produce a set of results which are broken down into five categories; costs, air quality, thermal loads, latent loads, and electric loads. One unique feature of ZEROs is its ability to predict air quality levels. This considers the use of ventilation and energy recovery equipment, including our soon to be released CERV (Conditioning Energy Recovery Ventilator). Another feature is breaking out the latent or moisture loads, which are extremely important in super houses, but often not handled in modeling software.

A validated energy model is important in designing a house, but as important is the validation of the constructed building’s performance. Blower door tests can point to construction flaws, but they don’t tell anything about the air quality and systems operation. In conjunction with ZEROs, our Black Box IAQ test ( records data related to Indoor Air Quality. This test assures that when habited, a building is providing a healthy environment for its inhabitants.

Follow the ZEROs link to try a fully functioning free version of the software. The subscription version is also available, which allows you to save different project cases and generate reports with the data as well as go into more depth with the parameters for windows and temperature and humidity set points. We hope you will find ZEROs to be useful and easy to use and in the end result in many more high performance, healthy, net zero energy residences across the country.