1. Level 3 Air Conditioning Inspections for Buildings
12. Assessing Equipment Sizing (Day 1)
PRESENTED BY
Anthony Balaam

2. Regulation 22 of EPB Regulations
Size – Versus - Load
Regulation 22 of EPB Regulations
“The inspection report must include an assessment of the air-conditioning efficiency and the sizing of the system compared to the ‘cooling requirements’ of the building, and contain appropriate advice on possible improvements to the system, replacement of the system and any alternatives.”

3. Cooling Loads 1. Environmentally unacceptable
Overdesign and Over-sizing Creates:-
1. Environmentally unacceptable
2. Operational at part load, generates reduced efficiency
3. Uneconomical
4. Overall wasteful
Under-sizing Creates:-
1. Conditions required for thermal comfort will ‘not be met’.

4. Ambient Design Temperatures
Cooling Loads
Ambient Design Temperatures
1. The selection of design ambient temperatures affects cooling duty;
These are obtained from established ‘weather data’ (summer time temperatures).
2. It is possible for cooling applications that:-
temp°C determining the cooling load ≠ temp°C sizing the cooling plant.
E.g. a dry bulb temperature of 28°C may be used for cooling load calculations, but a temperature of 32°C taken for selecting air cooled plant condensing equipment.
Note:- overestimation of cooling load – enables operation at higher ambient (but the plant will be marginally oversized).

5. Heat Gains The following contribute to the cooling load:-
Heat Gains – Can Cycle From ‘Zero’ to ‘100%’
The following contribute to the cooling load:-
1. Heat flow through walls, floors, roofs, doors, glazing.
2. Heat from air changes from doors, windows, ventilation systems.
3. Heat from solar radiation.
4. Heat from people within occupied zones.
5. Heat from lighting and other energy consuming equipment.
6. Heat from fans and pump motors associated with the systems.
(be aware of being paid for twice!)

6. Cooling Design Detailed calculations to reasonable accuracy.
Design conditions
Internal heat gain (sensible and latent)
Building use data
Admittance
Fabric details
U-values
Fabric heat gain (sensible)
Duct/fan heat gains
Fresh air ventilation load (sensible and latent)
Architectural layouts and elevations
Solar data
Solar heat gain (sensible)
Infiltration heat gain (sensible and latent)
Building air tightness
Psychometrics
Sensible/total room ratio
Total room heat gain (sensible and latent)
Detailed calculations to reasonable accuracy.
Part L compliance (post 2002) will limit oversizing to 15-20%.
Plant selection limitations cause oversizing.
Room cooling emitter size
Distribution pipework heat gains
Pipework distribution system design
Central Cooling Load
Dehumidification load
Cooling load diversities
MAXIMUM INSTANTANEOUS COOLING LOAD
Chillers Selection
Plant size ratio

7. Design Recommendation guidance
Cooling Design
Design Recommendation guidance
Literature:-
1. CIBSE Guide A: Environmental Design
2. CIBSE TM37: Improved Design for Solar Shading Control
3. CIBSE TM46: Energy Benchmarks
4. BSRIA: Rules of Thumb - Guidelines for Building Services
5. BSRIA/CIBSE: A Practical Guide to HVAC Building Services Calculations
6. BSRIA/CIBSE: Illustrated Guide to Mechanical Building Services
7. CIP (central information point) database file (available from
Software:-
1. Hevacomp
2. IES
3. Design Builder
4. TAS
Design recommendations for internal temperature and humidity are also well
documented in CIBSE Guide A(2), but an important factor will be the
acceptable limits set. For example, a room condition may be specified as
21 °C dry-bulb, 50% humidity. Will comfort conditions still be acceptable at
24 °C and 60% humidity under the maximum outside ambient? If the answer
is yes, then the cooling load can be reduced significantly to meet the design
conditions within these limits.
There are several software packages available for determining the cooling
load for any building, most based on CIBSE or ASHRAE data. It is important
to bear in mind the requirements of the Energy Performance of Buildings
Directive(3), which came into force on 4 January This is intended to lead
to reduced energy consumption by buildings, which will in turn lead to
reduced CO2 emissions. Legislation to implement the Directive within the
UK has been in place since 4 January 2006 and affects all buildings, both
domestic and non-domestic. Building Regulations Part L(4) was amended for
this purpose in 2006 and includes provisions for:
— setting ‘whole building’ carbon dioxide emissions targets for new
buildings
— setting performance standards for alterations to existing buildings (with
an option to use carbon dioxide targets where appropriate)
— specifying the National Calculation Method(5) for calculating energy
performance, based on the Standard Assessment Procedure(6) (SAP
2005) for dwellings, and the Simplified Building Energy Model(7) (SBEM)
or approved commercial software for other buildings
— incorporating low and zero carbon (LZC) energy systems into
buildings with a floor area greater than 1000 m2, e.g. combined heat
and power (CHP), solar panels, ground source heat pumps and
biomass
— certifying the energy performance of buildings (dwellings only at
present, but eventually for all buildings).

8. Cooling Estimation Estimate of current loads.
What is Required:-
Estimate of current loads.
Which provides:-
An Indication of whether the system is of appropriate size.
An Indication of the current state of the building and the system.
Does assists in:-
Future maintenance, replacement or upgrading of the system.

9. Cooling Estimation It helps to inform on:- It will indicate:-
replacement by like-for-like;
or whether smaller more efficient system will suffice.
It will indicate:-
Specific and localised load issues
Special cooling measures required
Or identification of oversized plant
Remember - Waste of energy is costly.

10. Unitary or Packged Systems
Rules of Thumb Guidance values:-
For units up to 7m from windows:-
100W/m2 for up 25% glazing
160W/m2 for up to 60% glazing
For units beyond 7m from the windows (internal areas):-
75W/m2
For larger areas (perimeters plus internal areas)
110 W/m² for 30% glazing

11. Unitary or Packged Systems
Rules of Thumb:-
Estimation Only! Does not account for :-
‘orientation’,
‘windows details’,
‘shading details’ (whether external or internal),
or ‘site details’ (adjacent buildings, trees etc.).
Significant factors should be noted in your site notes.

12. Unitary/ Packaged Centralised Systems
Design Guidance:-
Literature:-
CIBSE Guide A: Environmental Design
CIBSE TM37: Improved Design for Solar Shading Control
CIBSE TM46: Energy Benchmarks
BSRIA: Rules of Thumb - Guidelines for Building Services
BSRIA/CIBSE: A Practical Guide to HVAC Building Services Calculations
BSRIA/CIBSE: Illustrated Guide to Mechanical Building Services
CIP database file (available from
Software:-
Hevacomp
IES
Design Builder
TAS
Population Density example:-
70 people in an office 800sq.m = 11.5sq.m per person
Upper value 58w/sq.m
Lower value 32w/sq.m
Upper value
lower value

13. Method 1 Example 1 Method 1 :- Rule of thumb
1 - Internal Area (I) 1m
2 - Perimeter Area (P)
Upper Heat Gain :-= 7,750W / 80m2
= 97 W/m2 8m
Total Floor Area = 80m2
Glazing = <25%
Method 1 :-
Rule of thumb
Using Rules of Thumb (CIBSE:TM44):- (I + P)
1 - Internal Area Heat Gain = 75W/m2 * (10m*1m) = 750W
2 - Perimeter Area Heat Gain = 100W/m2 * (7m*10m) = 7,000W
Total Zone Heat Gain = 750W +7,000W = 7,750W = 7.75kW
+20% Tolerance = 9.3kW
Installed machine Capacity = 12.5kW
Installed Capacity is deemed to be more than expected (using rules of thumb)

14. Method 2 Example 2 Method 1 :- Rule of thumb
1 - Internal Area 1m
2 - Perimeter Area
Upper Heat Gain :-= 8,800W / 80m2
= 110 W/m2 8m
Total Floor Area = 80m2
Glazing = <30%
Method 1 :-
Rule of thumb
Using Rules of Thumb (CIBSE:TM44):- (larger areas)
1 - Internal Area Heat Gain + Perimeter heat gain = 110W/m2 * (10m*8m) = 8,800W
Total Zone Heat Gain = 8,800W = 8.80kW
+20% Tolerance = 10.56kW
Installed machine Capacity = 12.5kW
Installed Capacity is deemed to be more than expected (using the average rules of thumb)

15. Method 3 Example 3 10m 1 - Internal Area 1m 2 - Perimeter Area 8m
CIBSE Rule of ‘occupation density’
Area = 8m * 10m = 80m²
Density/m² = 80/12 = 6.7m²/p 8m
Total Floor Area = 80m2
Glazing = <25%
12 people
Occupants: 12No (Using CIBSE GUIDE A graph)
Lower value = 43W/m² of floor space
Upper value = 78W/m²
LV = 80m² * 43W/m² = 3,440W
UP = 80m² * 78W/m² = 6,240W
Total Heat Gain range = 3,440W * (1+20%) = 4.128kW to 6,240W*(1+20%) = 7.49kW
Installed Capacity = 12.5kW
Installed Capacity is more than expected

16. Method 4 Example 4 Upper Heat Gain = 13,330W / 80m2 = 167 W/m2 10m
1 - Internal Area 1m
2 - Perimeter Area
Upper Heat Gain = 13,330W / 80m2
= 167 W/m2 8m
Total Floor Area = 80m2
Glazing = <25%
Method 4 :-
CIBSE Rule of ‘occupation’
Occupants: 115W per person (SITE SURVEY + CIBSE GUIDE A)
Equipment: 1No 150W, 1No 450W
(SITE + CUIDE GUIDE A)
Lighting:
(SITE SURVEY)
Solar:30W/m², pre2002 building ADL2B
Occupants: 70 * 115W = 8,050W
Equipment: 150W + 450W = 600W
Lighting: (22*100W) + (4*20W) = 2,280W
Solar: 30W/m2* 80m2 = 2,400W
Total Heat Gain = 13,330W = 13.3kW
+20% Tolerance = 16kW
Installed Capacity = 12.5kW
Installed Capacity is Less that of expected

17. Method 2 Example 2 Revised Method 2 :- Rule of thumb
1 - Internal Area 1m
2 - Perimeter Area
Upper Heat Gain :-= 8,800W / 80m2
= 110 W/m2 8m
Total Floor Area = 80m2
Glazing = <30%
Revised Method 2 :-
Rule of thumb
Using Rules of Thumb (BSRIA 5th Edition from table = 87W/m²):-
1 - Internal Area Heat Gain + Perimeter heat gain = 87W/m2 * (10m*8m) = 6,960W
Total Zone Heat Gain = 6,960W = 6.96kW
+20% Tolerance = 8.352kW
Installed machine Capacity = 12.5kW
Installed Capacity is deemed to be more than expected (using the average rules of thumb)

18. Reference Material
“Heating, Ventilation, Air Conditioning and Refrigeration”, CIBSE Guide B, Chartered Institute of Building Services Engineers, 2005 “CIBSE KS13: Refrigeration”, CIBSE Knowledge Series, Chartered Institute of Building Services Engineers, 2008 “ASHRAE Handbook: Fundamentals”, American Society of Heating, Refrigeration and Air Conditioning Engineers, 2001 “BS EN 378: Specification for Refrigeration Systems and Heat Pumps; Part 1: 2000: Basic Requirements, Definitions, Classification and Selection Criteria; Part 2: 2000: Design, Construction, Testing, Marking, and Documentation; Part 3: 2000: Installation Site and Personal Protection; Part 4: 2000: Operation, Maintenance, Repair and Recovery”, London: British Standard Institution, 2000 “Non-Domestic Heating, Cooling, and Ventilation Compliance Guide”, Department For communities and local Government Building Regulations Approved Document L2B”, Department For communities and local Government “Inspection of Air Conditioning Systems”, CIBSE TM44:2007

19. LEVEL 3 Air Conditioning ENERGY ASSESSORS TRAINING
ANY QUESTIONS OR FEEDBACK ON ANY SLIDE
Any questions or clarity needed over this topic and slides 19

20. Contacts:- STROMA Certification Ltd – Contacts Web Links
Contacts:-
STROMA Certification Ltd.
4 Pioneer Way, Castleford, WF10 5QU

21. End of this section
Test 2 -. Package Systems Cooling Exercise – Question 1 a,b,c,d

22. Example 1 Method 1 Rule of thumb Using Rules of Thumb (CIBSE:TM44):-
1 - Internal Area 4m
Upper Heat Gain :-= 7,750W / 80m2
= 97 W/m2
10m
Total Floor Area = 200m2
Glazing = <25%
Method 1
Rule of thumb
2 - Perimeter Area
Using Rules of Thumb (CIBSE:TM44):-
1 - Internal Area Heat Gain = 75W/m2 * (20m*4m) = 6,000W
2 - Perimeter Area Heat Gain = 100W/m2 * (6m*20m) = 12,000W
Total Zone Heat Gain = 6,000W +12,000W = 18,000W = 18.00kW
+20% Tolerance = 21.6kW
Installed machine Capacity = 12.5kW
Installed Capacity is deemed to be less than expected (using rules of thumb)