Btu (th)/Minute/Square Foot

The unit Btu (th)/minute/square foot is commonly used in the field of heat transfer and building energy analysis to quantify the rate of heat flux through a surface. Here, Btu (th) stands for British thermal units in terms of thermal energy, and the measurement indicates the amount of heat energy transferred per minute through one square foot of surface area. This unit is particularly important in evaluating insulation efficiency, designing heating and cooling systems, and assessing the thermal performance of walls, roofs, and windows. For example, a higher Btu (th)/minute/square foot value implies more heat is passing through a surface, indicating poor insulation, whereas a lower value indicates better thermal resistance and energy efficiency. Engineers and architects often use this unit to calculate building loads, select appropriate materials, and ensure occupant comfort while minimizing energy consumption. In addition, it serves as a standard measure in energy audits, helping to compare different construction methods or retrofitting solutions. Understanding and applying Btu (th)/minute/square foot measurements allows for accurate prediction of heating or cooling requirements, cost estimation, and optimization of HVAC systems. Accurate calculations in this unit ultimately contribute to sustainable building design and energy conservation.

Dyne per Hour per Centimeter [dyne/(h·cm)]

The unit dyne per hour per centimeter, written as dyne/(h·cm), measures force per unit length over time, often used in contexts such as viscous drag, material creep, or very slow mechanical processes in cgs (centimeter-gram-second) units.

A dyne is the cgs unit of force, defined as the force required to accelerate 1 gram of mass by 1 cm/s². Therefore, 1 dyne = 10⁻⁵ newtons in SI units. The additional division by centimeter represents a per-unit-length measure, and division by hour accounts for time rate.

Mathematically, the quantity can be expressed as:

where F is force in dynes, L is length in cm, and t is time in hours.

Applications include:

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  Creep or stress studies in materials under very small forces over long periods

  
  
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  Lubrication or viscous flow measurements in cgs-based engineering studies

  
  
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  Experimental mechanics where small forces per unit length are measured over extended time

  
  

Conversion to SI units:

This unit is largely of historical or specialized interest but provides a precise cgs-based measure for extremely slow, small-force phenomena.