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

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.”

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’.

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).

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!)

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

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 www.ndepcregister.com) 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 2003. 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).

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.

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.

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

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.

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 www.ndepcregister.com) 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

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)

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)

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

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: 70No @ 115W per person (SITE SURVEY + CIBSE GUIDE A) Equipment: 1No Laptop @ 150W, 1No Projector @ 450W (SITE + CUIDE GUIDE A) Lighting: 22lamps@100W, 4@20W (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

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)

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

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

Contacts:- STROMA Certification Ltd – Contacts Web Links www.stroma.com/certification Contacts:- STROMA Certification Ltd. 4 Pioneer Way, Castleford, WF10 5QU 0845 621 11 11 training@stroma.com

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

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)