Energy Efficient Cooling concepts

What's on Lecture 3?

❖ What is HVAC load

❖ Heat load calculations (example)
❖ Heat load Software
Energy Efficient Cooling concepts
 Energy Efficient Cooling concepts

Factors to consider during Cooling load requirements

It is necessary for air conditioning designers to know about the heat

source and their nature before designing of air conditioning system.

▪ Building detailed layout

▪ Building orientation
▪ Ambient condition
▪ Use of Space
▪ Physical dimension of space
▪ Indoor design condition
▪ Filtration level required
▪ Glass area exposed to sun
▪ Occupancy
▪ Lighting load
▪ Equipment load
▪ Fresh air requirement
▪ Infiltration of outside air
 Energy Efficient Cooling concepts

Application of HVAC System

❖ Residential
❖ Commercial
❖ Industrial
❖ Educational
❖ Pharmaceuticals
❖ Hospitals
❖ Malls/Offices
❖ And many more….
 Energy Efficient Cooling concepts

Air Conditioning Load Estimate

❖ The air conditioning load is to provide the basis of selecting the

conditioning equipment.
❖ The load is designed for maximum conditions of heat such as:
• Peak month
• Peak day and
• Peak time of the year

❖ The design load is divided into two types.

• Outdoor load
• Indoor load
 Energy Efficient Cooling concepts

Outdoor loads
 Energy Efficient Cooling concepts

Indoor loads
 Energy Efficient Cooling concepts

Heat transfer
 Energy Efficient Cooling concepts

Human Comfort
 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

To ensure that the heating and cooling equipment and distribution systems can
keep the indoor temperature comfortable. This usually means an indoor
temperature of 20-22 0 c

We calculate the equipment requirements for each and ensure the heating and
cooling loads are met by the equipment and distribution systems to be Installed.
 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

Heat Loss = sensible heat loss only

Heat Gain = sensible heat gain + latent heat gain

Sensible heat gain: The amount of heat that each zone

gains from the warm outdoor air and sun.

Latent heat gain: The additional work the cooling

equipment must do to condense and remove the water
vapour in the hot/humid indoor air

Total heat gain = sensible + latent

 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

We calculate the heat loss of a building and select heating

equipment and distribution system to meet 100% of the
heat loss or heating load.

We calculate the heat gain of a building and select

cooling equipment to meet 80% of the total heat gain.
(The equipment doesn’t have to provide maximum
cooling to all zones simultaneously due to the changing
location of the sun)

The cooling system distribution equipment must be able

to deliver 100% of the sensible cooling load.
 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

Building Model A
Heat Loss (from calculations): 40,000 BTUH
The heating equipment installed must be greater than
40,000 BTUH
 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

Building Model A
Heat Gain (from calculations): 30,000 BTUH (Sensible) +
9,000 BTUH (Latent) = 39,000 BTUH (Total)

The cooling equipment installed must be greater than

39,000 BTUH X 80% = 31, 200 BTUH
(other criteria also considered per CSA F280-12)

The cooling distribution system must be able to deliver

100% of the sensible heat gain to each zone =
30,000BTUH
 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

 Energy Efficient Cooling concepts

Calculating heat Loss or Gain

 Energy Efficient Cooling concepts

Heat load calculation

 Energy Efficient Cooling concepts

Wall/Roof heat load

 Energy Efficient Cooling concepts

Glass heat load

The shading coefficient is calculated by the equation SC = SHGC / 0.86. For example, for glazing with a SHGC
of 0.6, we have 0.6 / 0.86 = 0.69, so the shading coefficient (SC) is 0.69.

Managers can calculate the cooling load for each piece of equipment by multiplying either: the number of
watts by 3.4 to produce Btu; or volts by amps by 3.4 to produce Btu. Add up all the units' Btu to determine
the equipment's total cooling load, and divide the Btu by 12,000 to determine the tons.
 Energy Efficient Cooling concepts

Heat load calculation

 Energy Efficient Cooling concepts

Heat load calculation Example

N

W
Section A E

Number of Person = 110

Total Floor Area = 4708.5 𝒎𝟐

S
 Energy Efficient Cooling concepts

A. Solar Heat Gain for Wall and Floor

𝑄 = 𝑢 × 𝐴 × ∆𝑇

Condition of Wall Area in 𝒎𝟐 Temperature in °C U factor Watts(W)

West partition 730 29 0.36 7621.20

North Exposed 451.5 31 0.3 4198.95

South Partition 645 29 0.36 6733.80

Floor 4708.5 29 0.19 25943.84

Total 44497.79
 Energy Efficient Cooling concepts

B. Solar Heat Gain for Glass

𝑄 = 𝐴 × 𝑆𝐶 × 𝑆𝐶𝐿

Condition of Wall Area in 𝒎𝟐 SC SCL Watts(W)

North Exposed 193.5 0.8 16.08 2489.28

Total 2489.28

Total Solar Heat Gain A+B 46,990.06 W

 Energy Efficient Cooling concepts

C. Effective Room Sensible Heat Load (E.R.S.H.L)

𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑡ℎ𝑒 𝑟𝑜𝑜𝑚 𝑥 𝑁𝑜.𝑜𝑓 𝑎𝑖𝑟 𝑐ℎ𝑎𝑛𝑔𝑒𝑠 4708.5×10×2
𝟏. 𝑂𝑢𝑡𝑠𝑖𝑑𝑒 𝐴𝑖𝑟 = 60
= 60
= 1569.5 𝑚3

𝟐. 𝑄𝑠 𝑆𝑒𝑛𝑠𝑖𝑏𝑙𝑒 𝐻𝑒𝑎𝑡 = 𝑚3 × ∆𝑇 × 𝑏𝑓 × 1.08

1569.5 × 34 × 0.15 × 1.08
8,644.8 W
𝟑. 𝐼𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝐻𝑒𝑎𝑡
= 𝑁𝑜. 𝑜𝑓 𝑃𝑒𝑜𝑝𝑙𝑒 × 𝑆𝑒𝑛𝑠𝑖𝑏𝑙𝑒 𝐻𝑒𝑎𝑡 𝐺𝑎𝑖𝑛
= 110 × 245 = 𝟏𝟕, 𝟏𝟓𝟎 𝐖
𝟒. 𝐿𝑖𝑔ℎ𝑡 𝐿𝑜𝑎𝑑
= 𝑇𝑜𝑡𝑎𝑙 𝑎𝑟𝑒𝑎 𝑚3 × 𝑙𝑖𝑔ℎ𝑡𝑖𝑛𝑔 𝑙𝑜𝑎𝑑 𝑤𝑎𝑡𝑡𝑠
= 4708.5 × 2 = 𝟗, 𝟒𝟏𝟕 𝑾

𝟓. 𝐸𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝑙𝑜𝑎𝑑 = 𝑁𝑜. 𝑜𝑓 𝐸𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 × 𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝑙𝑜𝑎𝑑 𝑤𝑎𝑡𝑡𝑠 = 90 × 300

= 𝟐𝟕, 𝟎𝟎𝟎 𝐖
 Energy Efficient Cooling concepts

𝟔. 𝑇𝑜𝑡𝑎𝑙 𝑆𝑒𝑛𝑠𝑖𝑏𝑙𝑒 𝐻𝑒𝑎𝑡 𝐿𝑜𝑎𝑑(A+B+C)

= 44,497.78 + 2,492,28 + 8,644.8 + 17,150 + 9,417 + 27000 = 𝟗𝟗, 𝟕𝟖𝟒. 𝟖𝟔 𝑾

Safety Factor 8%

𝟕. 𝐸𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑅𝑜𝑜𝑚 𝑆𝑒𝑛𝑠𝑖𝑏𝑙𝑒 𝐻𝑒𝑎𝑡 𝐿𝑜𝑎𝑑 = 𝟏𝟎𝟓, 𝟕𝟕𝟏. 𝟗𝟓 𝑾

 Energy Efficient Cooling concepts

D. Effective Room Latent Heat Load (E.R.L.H.L)

. 𝟏. 𝑄𝑙 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 = 𝑂𝑢𝑡𝑠𝑖𝑑𝑒 𝑎𝑖𝑟 × ∆𝑤 × 𝑏𝑓 × 0.68 =

1569.5 × 36 × 0.15 × 0.68 = 𝟓, 𝟕𝟔𝟑. 𝟐𝟎𝟒 W

𝟐. 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝐼𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝐿𝑜𝑎𝑑 = 𝑁𝑜. 𝑜𝑓 𝑃𝑒𝑜𝑝𝑙𝑒 × 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝐺𝑎𝑖𝑛

= 110 × 205 = 𝟐𝟐, 𝟓𝟓𝟎 𝑾

𝟑. 𝑇𝑜𝑡𝑎𝑙 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝐿𝑜𝑎𝑑 = 5,763.204 + 22,550 =

𝟐𝟖, 𝟑𝟏𝟑. 𝟐𝟎𝟒 𝑾 Safety factor

𝟒. 𝐸𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑅𝑜𝑜𝑚 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝐿𝑜𝑎𝑑 = 𝟑𝟎. 𝟓𝟕𝟖 𝑾

 Energy Efficient Cooling concepts

E. Effective Room Total Heat Load (E.R.T.H.L)

𝐸. 𝑅. 𝑇. 𝐻. 𝐿 = 𝐸. 𝑅. 𝑆. 𝐻. 𝐿 + 𝐸. 𝑅. 𝐿. 𝐻. 𝐿 = 𝟏𝟎𝟓, 𝟕𝟕𝟏. 𝟗𝟓 + 𝟑𝟎. 𝟓𝟕𝟖

= 𝟏𝟑𝟔, 𝟑𝟒𝟗. 𝟗𝟓 𝑾

136.3𝐾𝑤
𝑇𝑅 = 136,349.95 𝑊𝑎𝑡𝑡𝑠 = = 𝟑𝟖. 𝟗𝑻𝑹
3.5𝐾𝑤
𝐸. 𝑅. 𝑆. 𝐻. 𝐿 105,771.95
𝑭. 𝐸𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑅𝑜𝑜𝑚 𝑆𝑒𝑛𝑠𝑖𝑏𝑙𝑒 𝐻𝑒𝑎𝑡 𝐹𝑎𝑐𝑡𝑜𝑟 = = = 𝟎. 𝟕𝟕
𝐸. 𝑅. 𝑇. 𝐻. 𝐿 136,492.87
𝐸. 𝑅. 𝑆. 𝐻. 𝐿 105,771.95
𝑮. 𝐷𝑒ℎ𝑢𝑚𝑖𝑑𝑖𝑓𝑖𝑒𝑑 = = = 𝟓, 𝟒𝟒𝟎. 𝟗𝟒
1.08 × (𝑅𝑇 − 𝐴𝐷𝑃) 1.08 × (72 − 54)

Capacity: 39 TR
Airflow: 5, 441 m3/min
 Energy Efficient Cooling concepts

Heat load calculation

 Energy Efficient Cooling concepts

Heat load calculation

 Energy Efficient Cooling concepts

Heat load calculation