Heat Gain Formula

Heat is a type of energy, and the pace at which energy is consumed is referred to as the power. Watts are used to assess the rate at which heat energy is used, which is also known as power loss. Solar energy is absorbed in the exterior surface, which is represented by the air temperature, and this affects heat gain via walls and roofs. Because it exists with the real air temperature, it is the external temperature that would provide the same heat gain through the element without solar energy.

Heat Gain

Heat gain refers to a temperature increase in a space caused by incoming sunlight (sunlight), heat from the outer surface (long-wave infrared radiation), and heat from other channels within the space (such as heaters, hobs, individuals, mechanical systems, lights, and computers), among other things.

Formula

q = 1.10 × cfm × (t₀ – t_i)

where,

• cfm denotes the flow rate with which air rushes inside the building.
• t₀ is the temperature outside.
• t_i is the temperature inside.

Sample Problems

Question 1. Find the heat gain rate for the flow rate of 9000 cfm, t₀ = 77°F and t₁ = 70°F.

Solution:

Given: cfm = 9000, t₀ = 77F, t₁ = 70F

Since, q = 1.10 × cfm × (t₀ – t_i)

q = 1.10 × 9000 × (77 – 70)

q = 69300 KW

Question 2. Find the heat gain rate for the flow rate of 4000 cfm, t₀ = 69°F and t₁ = 63°F.

Solution:

Given: cfm = 4000, t0 = 69F, t1 = 63F

Since, q = 1.10 × cfm × (t0 – ti)

q = 1.10 × 4000 × (69 – 63)

q = 26400 KW

Question 3. Find the heat gain rate for the flow rate of 2330 cfm, t₀ = 45°F and t₁ = 40°F.

Solution:

Given: cfm = 2330, t₀ = 45F, t₁ = 40F

Since, q = 1.10 × cfm × (t0 – ti)

q = 1.10 × 2330 × (45 – 40)

q = 12815 KW

Question 4. Find the heat gain rate for the flow rate of 1200 cfm, t₀ = 56°F and t₁ = 52°F.

Solution:

Given: cfm = 1200, t₀ = 56F, t₁ = 52F

Since, q = 1.10 × cfm × (t0 – ti)

q = 1.10 × 1200 × (56 – 52)

q = 5280 KW

Question 5. Find the heat gain rate for the flow rate of 3500 cfm, t0 = 71°F and t1 = 68°F.

Solution:

Given: cfm = 3500, t0 = 71F, t1 = 68F

Since, q = 1.10 × cfm × (t0 – ti)

q = 1.10 × 3500 × (71 – 68)

q = 11550 KW

Question 6. Find the heat gain rate for the flow rate of 5500 cfm, t0 = 34°F and t1 = 29°F.

Solution:

Given: cfm = 5500, t0 = 34F, t1 = 29F

Since, q = 1.10 × cfm × (t0 – ti)

q = 1.10 × 5500 × (34 – 29)

q = 30250 KW

Question 7. Find the heat gain rate for the flow rate of 3800 cfm, t0 = 76°F and t1 = 72°F.

Solution: 

Given: cfm = 3800, t0 = 76F, t1 = 72F

Since, q = 1.10 × cfm × (t0 – ti)

q = 1.10 × 3800 × (76 – 72)

q = 16720 KW