Passive Design Strategy Calculators
The Idaho Power Company and Integrated Design Lab Climate Tools Package is a series of excel spreadsheets intended to assist in the process of designing and evaluating the application of passive strategies on a project. The different spreadsheets are designed to first calculate the peak heat gain rate of the building and then compare this value to a variety of different passive design measures’ cooling capacities.
Currently, there are four different spreadsheets:
- Heat Gain Calculations
- Cross Ventilation
- Stack Ventilation
- Night Ventilation Thermal Mass
Each spreadsheet contains multiple tabs and a step-by-step process that directs the user to define the critical parameters of the building. These factors are linked to pre-defined equations within the spreadsheet that automatically provide the peak cooling loads, cooling capacities, and other performance metrics of the building. Charts, line graphs, and other forms of graphic information also automatically populate the workspace to provide visual feedback to the user. The last tab of the spreadsheets contain a reference tab that includes a myriad of textbook, code, and other sources needed to complete the step-by-step instructions. Additionally, a certain amount of weather data is embedded into the calculations and spreadsheet based upon the different Idaho Power Company service territories. Once each tab is filled out, the first page of the spreadsheet contains all of the important outputs needed to evaluate how much the passive design measure can contribute to the peak loads of the building. Changes to the building parameters are instantaneous, making the Climate Tools Package an ideal instrument used to explore different design iterations and how they might facilitate passive design strategies.
Goals
The ultimate goal of the Climate Tools Package is to reduce the loads of a building through passive design measures. This happens mainly by embedding, early in the design process, the analysis of the performance capabilities of different passive cooling and heating strategies. Once a performance capacity is calculated and compared against peak loads of a building, a qualitative decision can be made whether or not to pursue more detailed analysis. If certain passive strategies are proven to meet some or all of the peak load, this may warrant further development. Potential next steps could involve more advanced analysis such as building simulation to quantify annual energy savings based on actual weather data.