Skip to content

Intro to Rules Engine

Jump to bottom
Thad Kerosky edited this page Aug 30, 2023 · 8 revisions

Glossary

  • billing period: For a given bill that a homeowner is charged for their heating usage, the billing period is the time range (defined by a start date and an end date) for which they are being billed. On the HEAT app, users will upload their heating usage data for multiple billing periods.
  • BTU: British Thermal Units - a common measuring unit for heat
  • UA: also known as the whole-home heat transfer rate, UA is a measurement of how quickly a home loses heat (units are BTU per hour per degree F)
  • Thermostat set point: the average interior temperature that is desired by the homeowner - what they program their thermostat to
  • Balance point: the outside temperature above which no heating is required for a given home to maintain its thermostat set point. By definition, the balance point is less than or equal to the thermostat set point.
  • Heating Degree-Days (HDD): For a single day, HDD refers to the number of degrees between the average outside temperature and the balance point. HDD is non-zero only when the outside temperature is colder than the balance point - if the outside temp is >= balance point, no heating is required, which by definition means HDD = 0. For a multi-day time period, the total HDD is the sum of the single-day HDDs.
  • Average heat load: the amount of energy that a heating system needs to produce in order to maintain a desired thermostat set point within a given home on an average day
  • Max heat load: the amount of energy that a heating system needs to produce in order to maintain the design set point within a given home when the outside temperature is the design temperature
  • Design set point: a standard internal temperature / thermostat set point - different from the preferred set point of an individual homeowner
  • Design temperature: an outside temperature that represents one of the coldest days of the year for the given location of a home. Heating systems are designed to this standard to ensure that they're powerful enough to handle some of the worst cold, not just the average cold

Rules Engine Steps

  1. Read in the billing periods data and categorize them by season.
  2. Calculate the average daily non-heating usage (if fuel type is gas, this is the average daily summer-month usage. Otherwise, it's 0)
  3. Calculate the average daily heating usage (average daily total usage in winter months minus average daily non-heating usage)
  4. Calculate the UA and the balance point. This is a semi-iterative process
  5. Calculate average indoor temp: ((24 - setback hrs per day) * tstat setting + setback hrs per day * setback temp)/24
  6. Calculate avg heat load: (design set point - (avg indoor temp - balance point) - design temp) * UA
  7. Calculate max heat load: (design set point - design temp) * UA

Frontend-Rules Engine Questions

Clone this wiki locally