When does delta T begin to measure or read?

Delta T, or temperature difference, is a critical measure in assessing the performance of a building's heating and cooling systems. It begins to register or read when there is a 1-degree difference in temperature between two zones. This benchmark is significant as it helps to ensure that any temperature differential that is being measured is relevant and can indicate whether there is a substantial enough difference that may affect comfort levels or system efficiency.

When delta T is noted to start at 1 degree, it provides a standard threshold that allows for effective monitoring and evaluation of a building's climate control systems. It means the systems can be assessed for efficiency and performance in truly representative conditions. This reading is useful in pinpointing issues such as air leaks, inadequate insulation, or system malfunctions which may arise when the temperature difference is minimal.

Using a 0.5-degree or a higher threshold, such as 2 degrees, might not yield as efficient or sensitive a measure for practical applications, which is why the 1-degree starting point is widely accepted in building analysis methodologies.