Case Studies

CHAPTER 6

CASE STUDIES

In absence of any type of quantifiable data with regard to energy use in office buildings in Lahore, Pakistan it is very difficult to understand the energy performance of the existing office buildings. It is, therefore, necessary to collect data with regard to energy consumption in office buildings using different methods.

One method was to collect information from utility bills; however, they provide information only with regard to total energy used in a building. It is therefore, decided that a computer simulation programme should be used for the assessment of energy consumption of selected office buildings. However, it is important to mention here that a lot of information in the form of design data, particular for HVAC & lighting will be needed to perform accurate programme simulation.

6.1 Selection criteria of Case Studies

In Pakistan we have is a wide range of office buildings, starting from a single storey structure to a high rise multi storey building. Selection of a building as a case study was a difficult task. But after setting a certain criteria, the selection becomes easier for us. The main points of our selection criteria are given below;

a) The building should be an office building.

b) The office building should be of medium size, between 7-10 storey

c) The building will have single use.

d) The building should be located in Lahore.

e) Total area of the building should be between 70,000 to 125,000 sft

f) Information for simulation should be available including Architectural, Electrical and HVAC design parameters.

6.2 Case Studies

Following buildings are selected as case studies.

A- Bank of Punjab Head office building Main Boulevard Gulberge III, Lahore.

B- JDEL Building at DESCON World Headquarters, 18-Ferozepure Road, Lahore.

Details of each building will be discussed with respect to following aspects.

· Location of the building.

· General description of the building.

· Architectural Consultants & Architectural drawings / details / sections / materials information provided by the consultant.

· Materials thermal properties.

· Electrical Consultants & Electrical drawings / lighting loads / equipment load and related information provided by the consultant.

· HVAC Consultant with HVAC design parameters with equipment details.

· On site photographs

6.3 Case Study “A” Bank of Punjab Head office Building

6.3.1 Location of the Building

Building is located to on the main boulevard Gulberge about ½ Km from Liberty round towards Kalma chowk.

6.3.2 General Description

The original name of the Project was the EPOCH Heights. Later on the name was changed by the Crescent Bank to Crescent Standard Tower. Recently (2007) the tower has been purchased by the Bank of Punjab and tower is now known as BOP (Bank of Punjab) Tower.

The building was designed by M/s Imtiaz Ali & Associates in 1997. The project was completed in the year 2002. The building is designed as an office building with two basements for car parking and thirteen office floors. The covered area of the building is 79,885 sft. Total area of the plot is 9,000 sft (64'-6” X 139'-7”).

6.3.3 The Architectural Design

Basic plan of the building is rectangular with smaller dimension is facing south-east, the sides with longer dimensions are facing north-east & south-west. The rear side is facing towards north-west orientation. The typical plan of the building is shown in [6.1][i]

TYPICAL FLOOR PLAN-r

The BOP tower is designed by Arch. Imtiaz Ali the principle architect of M/s IMTIAZ ALI Associates in 1997.

6.3.4 The Envelope

Envelope is the separation between the interior and the exterior of a building. It serves as to protect the interior comfort conditions from the outer environmental forces. The physical horizontal components of the envelope includes the following;

· The slabs

· Intermediate slabs & floors

Vertical components includes;

· Foundations

· Walls of all types

· Interior partitions

* Doors and Windows

The connections and interactions of the physical components of envelope are the main factors that determine the effectiveness of the building enclosure system

6.3.4.1 Horizontal Components of Envelope:

BOP Tower is a concrete frame structure building with flat plate slab construction. Building has two basements having a slab area of 9003 sft each, a Lower Ground floor with slab area of 4143 sft, one Upper Ground floor having a slab area of 4229 sft. Next ten floors are typical having a slab area 5197 sft each. The top floor is partially covered having a slab area of 1537 sft. Hence the total covered area of the building is 79,885 sft.

The two basements & Lower Ground floor, the ceiling height from FFL to soffit of slab is 8'-8”. The Upper Ground floor has the exception ceiling height of 11'-8” from FFL to soffit of slab. The typical floor heights from 1st floor to 10th floor are 8'-11” from FFL to soffit of slab. Finally the top floor clear ceiling height is 7'-0” only, so the total height of the building from road level to top of parapet is 130'-0”, and it is going -22'-6” down from road level for basements & lower Ground floor . The section of the building is given for further explanation in [6.2][ii] on the next page.

6.3.4.2 Materials of Construction

6.3.4.2a Floor Specifications with thermal Properties:

* The slabs/floors in basements & lower Ground Floor are 8” thick RCC slab with 2” PCC including hardener in basements. Lower Ground Floor is finished with floor tiles (Porcelain). The details of the floor/slab are given in [6.3] & [6.4].

* From Upper Ground floor to 10th floor flat plate slab thickness is 14 ½” with floor finish of porcelain mate tiles as shown in the [6.5]. On the top floor other specifications are same except the water proofing layers of bitumen, 2” thick polystyrene R-8 & 1 ½” thick Roofing tiles. The details of the floor/slab are given in the [6.6].

6.3.4.3 Vertical Components of Envelope:

BOP Building is a composite structure of concrete & brick walls. The building is facing to South-East orientation. The right side is North-East, Left side is South-West & rear side is North-West orientation. Each side is cladded with modern materials including Alpolic Sheet (Aluminum panels) on opaque surfaces and curved glass curtain wall in panels.

Detail of each side is given below;

a) S-E Elevation

Reference to the plan given below, the S-E is the front side of the building. On right corner the wall is 9” thick concrete, indicated in red color. On left corner the wall is in brick work indicated in mauve color indicated in [6.7][iii].

Aluminum panels have been used for cladding of wall surfaces; rest of the area is curved curtain wall as shown in the given photograph [6.8][iv].

The 9” thick RCC wall has the U-Value = 2.94 W/sq.m/K, while the single one way reflective glass has U-Value = 4.8 W/sq.m/K, The 9” thick brick wall has the U-Value = 2.23 W/sq.m/K & U-Value of Aluminum panels is 3.51 W/sq.m/K. The total glazed area of the elevation is 44.1% with Solar heat gain factor (SHGF) value of 0.75.

b) S-W Elevation

As indicated in the typical plan ( 6.7), the S-W is the left side of the building. On both sides of the façade indicated in mauve color, opaque surface are in 9” brick work, cladded with Aluminum panels (Alpolic). Central surface in curved shape is treated with way reflective curtain wall. As shown in the [6.9][v].

The 9” thick brick wall has the U-Value = 2.23 W/sq.m/K, The central curtain wall with single one way reflective glass has U-Value = 4.8 W/sq.m/K & U-Value of Aluminum panels is 3.51 W/sq.m/K. The total glazed area of the elevation is 46.5% with solar heat gain factor (SHGF) value of 0.75.

c) N-E Elevation

As indicated in [6.7], the N-E is the right side of the building. On left corner the wall is 9” thick concrete, indicated in red color. On right corner the wall is in brick work indicated in mauve color. Applications of the materials are the same as discussed in S-E & S-W elevations, except the glazed area 46.0% with same SHGF value of 0.75.

Keeping the same materials on this side, the thermal properties of the materials are also same. As shown on the photograph [6.10][vi].

d) N-W Elevation

Reference to the already discussed typical plan, the N-W is the rear side of the building, which is more flat as compared to the other three elevations, with the same material applications on the opaque surfaces. No curtain wall is provided considering the back of the building which has the least importance then the other three elevations. On left which is a lift well, 9” RCC wall is provided indicated in red color. While on the other corner the walls are in 9” brickwork of toilet block, indicated in mauve color ( 6.7).

6.3.5 The Electrical Services (Lighting Design)

The electrical engineering services are given by electrical consultant Mr. Naseem Rathore, ECON Associates, Gulberge Lahore. Consultant has designed the lighting services following the standards with respect to nature of space & illumination requirements.

Lighting requirements are different with the change in nature of space. In lobbies, Staircases & lift wells the lighting / illumination requirements are different then the other working areas of office floors. In a space we have to provide the lighting fixtures accordingly. On working tables & workstations task lighting illumination is always very important. For working conditions the required light illumination is 500 Lux/m.sq. which is different than the areas for general use where level of illumination is 300 Lux/m.sq. The standards given by the consultant for each area in the building are shown in table Tab. [6.1][vii].

Sr. #

Area Type

General Lighting

Task Lighting

Equipments Plug Load

w/sq.ft.

Office-General

3.0

3.5

2.5

Office (Executive/Private)

2.75

3.0

1.5

Conference/Meeting Rooms

3.0

1.0

Corridors

0.30

0.10

0.20

Lobbies, Staircases & Lifts

0.5

0.15

0.5

Kitchens/Food Preparation

1.75

0.1

0.2

Toilets

1.0

0.15

0.2

Mechanical/Electrical Room

0.7

0.2

Parking Areas

0.3

0.1

Storage Spaces

0.7

0.15

Tab. 6.1 Table showing the lighting equipment loads on different activity areas of building

Source: M/s Econ Associates

6.3.6 The HVAC Design

The Mechanical Engineering (HVAC) services are designed & executed by MIA Corporation. Same company has provided the HVAC equipment also. Basically this was a turnkey project for MIA Corporation.

HVAC Design parameters given below are collected from MIA Corporation later on these parameters are used to simulate the performance of the system.

6.3.6.1 HVAC Zones

TYPICAL PLAN HVAC ZONES.jpgThe HVAC zoning is according to the conditioned & non conditioned spaces of the building. The typical plan of the building is showing the conditioned & non-conditioned zones of the building as given below, [6.11][viii];

Source: M/s MIA Corporation

The area shown in light blue color is the Conditioned space including

i. Offices for all type

ii. Conference / Meeting rooms

iii. Entrance Lobbies / Staircase / Lift areas

And the areas shown in green color is the Non-Conditioned spaces including

i. Corridors

ii. Kitchens / Kitchenettes

iii. Toilet Blocks

iv. Storage Areas

v. Mechanical / Electrical Rooms

vi. Car Parking areas in Basements

6.3.6.2 Weekly Occupancy Schedule

The starting & closing times of the office indicate the occupancy hours of the spaces. The Occupancy hours of POB tower is Table [6.2][ix] as follows;

Sr. #

Day

Starting Time

Closing Time

Break Hours

Remarks

Monday

8:00 a.m.

5:00 p.m.

1.00 pm-2.0 pm

In break hours the office equipment & lighting requirements decreased But the HVAC load remains same

Tuesday

8:00 a.m.

5:00 p.m.

1.00 pm-2.0 pm

Wednesday

8:00 a.m.

5:00 p.m.

1.00 pm-2.0 pm

Thursday

8:00 a.m.

5:00 p.m.

1.00 pm-2.0 pm

Friday

8:00 a.m.

01:30 p.m.

1.30 pm-3.0 pm

3:00 p.m.

5:00 p.m.

Saturday

8:00 a.m.

01:30 p.m.

No Break

Sunday

O F F

Tab. 6.2 Table showing the Occupancy Schedule on weekly basis of BOP Tower

Source: M/s MIA Corporation

6.3.6.3 Cooling & Heating Set points

Cooling & heating set points (thermostat set temperatures) are concerned with the desired temperatures in summer & in winter. These set points are according to the least requirement of comfort conditions for the internal spaces in a building. It is also important to mention the set points (thermostat set temperatures) when the spaces are not occupied. The design parameters also required the cooling & heating set points (Design temperatures) at source & the minimum design flow of air in CFM (Cubic foot per minute). Different set points regarding heating & cooling are listed in table [6.3][x] below;

THERMOSTAT SET POINTS

Sr. #

Description

Occupied

Unoccupied

Cooling Set Points

76 Deg F

82 Deg F

Heating Set Points

70 Deg F

64 Deg F

DESIGN TEMPERATURES

Indoor

Supply

Cooling Set Points

75 Deg F

55 Deg F

Heating Set Points

72 Deg F

95 Deg F

Minimum Design Flow

2.0 cfm/ft. sq.

Tab. 6.3 Table showing the different temperature set points

Source: M/s MIA Corporation

These Thermostat & Design temperatures are according to the local climate of the area, the values will change according to the new climatic conditions.

6.3.6.4 Design Occupancy of Spaces per person

Occupancy of a space changes with the change in activity performed. For optimizing the cooling loads the occupancies of different spaces regarding the space requirements per person should be calculated including design ventilation per person per foot square.

The table [6.4][xi] given explains different areas with their occupancy and design ventilation rate.

Sr. #

Area Type

Design Max. Occupancy sft/Person

Design Ventilation cfm/person/ft.sq.

Office-General

Office (Executive/Private)

Conference/Meeting Rooms

Corridors

Lobbies, Staircases & Lifts

Kitchens/Food Preparation

Toilets

Mechanical/Electrical Room

130

Parking Areas

125

Storage Spaces

150

Table 6.4 showing % design ventilation air flow /person/sft and design maximum occupancy

6.3.6.5 HVAC Equipment Description

a) Heating system (Hot water Coils)

In BOP tower “Hot water coils” system is used for space heating.

Heating coil units that connect to air handlers provide forced-air heating in central air conditioning systems. In this way, heating and cooling systems can be combined to save space, components, and in some instances, energy and installation costs. The coil also provides an inexpensive way to increase a system's heating capacity for an addition.

The complete system consists of a hot water coil, the air handler/direct expansion coil assembly, a condenser and/or furnace, and a water heater or boiler. An optional pump in the coil keeps the water circulating for space heating while the pump in the hot water heater is used for domestic hot water. These coils can be mounted in up flow, down flow, or horizontal configurations.

b) Cooling System (DX Coils)

In BOP tower “DX Coils” system is used for space cooling. A brief description of the system used in given below;

A water chiller is used to add cooling and dehumidification to the systems. A refrigeration-type water chiller consists of a compressor, condenser, thermal expansion valve, and evaporator coil. The water is cooled in the evaporator coil and pumped through the system.

The boiler and water chiller are installed as separate units, each with its own circulator (pump), or with one circulator in the return line. Cold water is circulated through the piping from the water chiller for cooling purposes.

Water condensed from the coil during the cooling operation is trapped in a drip pan and discarded through a drain connected to the convector. Some convectors also contain a filter for air cleaning. The room convectors in a water chiller cooling system are usually designed for individual control. The same piping carries both the chilled and hot water to the room convectors, but it must be insulated to minimize condensation during the cooling operation.

Cooling can be applied to a warm-air heating system by installing an evaporator coil or a cold water coil in the ductwork. The evaporator coil is the low-side section of a mechanical refrigeration system. Evaporator coil is installed in the ductwork above the furnace. It is connected by refrigerant piping to the condenser coil and compressor installed outdoors.

A thermostatic expansion valve and condensation drip pan (with drain) is included with the evaporator coil. Sometimes a fan is added to the coil to supplement the furnace blower.

A cold-water coil may be used instead of an evaporator coil in the ductwork. Cold water is supplied to the coil by a water chiller, which can be located in the basement, a utility room, or outdoors. If the water chiller is installed outdoors, a gas engine can be used to drive the compressor.[xii]

6.3.7 Building Energy Performance Analysis

The energy simulation process requires data from all related consultants. Following information is collected for the energy simulation software;

* The Architectural detailing related to envelope construction details of the building from the Main Consultant.

* Electrical Drawings and electrical design parameters for internal lighting and office equipment.

* HVAC Design conditions & parameters from the Consultant and the equipment details from the HVAC system provider.

* Electricity block charges (energy rates) from Energy conservation centre Wapda House, Lahore.

* Weather data file (Lahore.bin) from www.doe2.com\index\weather.html

Following results are obtained from the simulation process.

Monthly Energy consumption by end-use in (kWh)

Annual Energy consumption by end-use in (kWh)

Total Annual energy Bill for the building components and systems including;

Building Fabric

HVAC System

Artificial Lighting

6.3.8 Analysis of Results

This research revolves around the factor responsible for increase/decrease of the internal cooling and heating energy loads. The factors we have already discussed concerned with the recent case study are;

· Envelope of the Building

· Interior Lighting

· HVAC

6.3.8.1 Annual / Monthly Energy Consumption

The Result shown in Fig [6.12][xiii] is concerned with the energy consumption on monthly basis during the whole year. The result shows the change in energy demand with the change in climatic conditions of the environment.

Results generated by eQuest 3.6

The Results shown in Fig [6.12][xiv] is concerned with the energy consumption on monthly basis during the whole year. The result shows the change in energy demand with the change in climatic conditions of the environment.

6.3.8.2 Area Lighting and Task Lighting

The lighting loads including general lighting (yellow color), task lighting (brown color), loads almost remains constant throughout the year consuming an average electricity (32.5x1000 KWh for area lighting, 37.5x1000 KWh for task lighting & 16x1000 KWh for office equipment), it reveals the fact that in office buildings, day lighting is not used for illumination purposes by putting vertical blinds on the fixed windows / glazed panels.

6.3.8.3 Space Cooling & Heating (HVAC)

The cooling loads (blue color) are varying with the change in climatic conditions throughout the year in Lahore. The maximum cooling load of (57.65x1000) KWh is observed during the month of June due to maximum outside temperature between 46 Cº to 48 Cº. On the other hand in January the cooling load is comparatively low (21x1000) KWh. The space heating loads (red color) having maximum value of (5.55x1000) KWh are observed during the month of January. The minimum heating loads are observed in the month of November (1.25x1000 KWh).

6.3.8.4 Ventilation

For the unconditioned area like car parking, storage areas, toilets, kitchenettes & mechanical/electrical rooms the minimum air flow requirement is 2.0 cfm/person/sft. This air flow is achieved by using ventilation fans (magenta color). The maximum energy loads of (8x1000 KWh) are coming during the month of June.

6.3.8.5 Office Equipment

Generally in office building the equipment load remains constant throughout the year, as is visible (Green color) from the results in Fig [6.12], In the BOP Tower the working conditions remains same for the whole year.

6.3.8.6 Total Energy Consumed

The result shown in Fig [6.13] indicates the total yearly energy (%) consumed in space cooling, heating, area general lighting, task lighting, office equipment and Ventilation.

The space cooling & heating systems are consuming about 33% of the total energy. While area lighting and task lighting is consuming 53% of the total energy that is very significant.

6.3.8.7 Cost of Energy Consumed

The result shown in Fig [6.13][xv] is related to the monthly energy bills of the energy consumed. It could be analyzed from results shown in s (6.11 & 6.12) that the energy demand is varying throughout the year with the change in climatic conditions. The bar chart shows that in February the energy demand is minimum during the whole year (227.7x1000) KWh which is 6.78% of the total energy consumed. On the other hand in June the energy load is maximum, which is 9.33% of the total energy consumed.

The average energy bill in one month is about (140x1000) Kwh amount to Rs. 1,314,690/- per month, as explained in the [6.14] on the next page.

6.3.8.8 Comparison of results with actual Energy Consumed

Average Monthly Bill is Rs. 1.3 Million

6.4 Case Study “B” JDEL Building at Descon World Headquarters

6.4.1 Location of the Site

Building is located to on 18-Km main Ferozepure road 7.3 Km from Kalma chowk towards south & 6.5 Km from the Centre of Model Town.

6.4.2 General Description

JDEL (J-Tech & Descon Engineering Limited Joint venture) situated in the Descon Estate 18-Km Ferozepure Lahore comprising a total area of 05-Acers. The building is the extension of an existing “Descon World headquarter” building, used by Descon co-cooperative offices. JDEL building was constructed to accommodate the employees under the joint venture between Descon Engineering Pvt. Ltd & J-Tech. Pvt. Ltd., as shown in the [6.15][xvi]

The building was designed by Arch. Umar Hassan, Oh+A Design Works, 7D Kashmir PAAF building, Egerton road, in 2005 & completed in 2008. The building is designed as an office building with one basement for car parking, Lower Ground & 06 office floors. The covered area of the building is 125,096 sft.

6.4.3 The Architectural Design

Basic plan of the building is rectangular with one side (Southern) not at right angle with the other sides, following the angular plot line of the Descon state, as indicated on the above site plan. As building is the extension of the existing head office, so the Western side is a dead wall (Adjacent wall between old & new building), indicated on the typical floor plan ( 6.16)[xvii]. The Eastern wall is a straight with minimum glazing, facing towards the J-Tech Building (A).

The conceptual design of the project was conceived by Arch. Omar Hassan the principle architect of M/s Oh+A Design Works.

JDEL Building is a concrete frame structure with column beam construction there is one basement and a Lower Ground floor, the ceiling height from FFL to soffit of slab is 10'-0” having covered area of 21,327 & 10383 respectively. The Upper Ground floor & typical floors starting from 1st to 5th floor the clear ceiling height from FFL to soffit of slab is 11'-0”, the slab area of upper ground and a typical floor is 12,417 & 16,343 sft respectively.

The total height of the building from Plinth level (+5'-0” from internal road level) to top of parapet is 80'-0”, and it is going 16'-0” down from the plinth level for basement & lower Ground floor.

6.4.4 The Envelope

JDEL Building is a composite structure of concrete columns & brick walls. The building is facing towards North orientation. The right side (West side) is a dead wall, adjacent with the existing structure of main Headquarter building, Left side is the East elevation facing towards the J-Tech building (A) & rear side, the angular one is on South orientation. Each side is cladded with a combination of 1 ½” thick “Gutka” facing brick tile and paneled color Crete with gray Portland cement (Mixture of CS mortar with marble chips) on opaque surfaces and clear glass is used on glazed surfaces. Detail of each side is given in Fig [6.17] on next page.

6.4.4.1 North Façade

Reference to the plan given (6.17), the North is the front side of the building. The North elevation has the maximum percentage of glazed panels (47.3%) as shown in the (6.18). The façade is composed with opaque & glazed surfaces. All exterior walls are 9” thick with an addition of 1 ½” thick “Gutka” facing brick tile and paneled color Crete with gray Portland cement (Mixture of CS mortar with marble chips). The brick walls are indicated in red color. The 9” thick concrete wall is indicated in “Cyan” color as shown in the given plan ( 6.17)[xviii].

The 9” thick brick wall including 1 ½” thick facing brick gutka has the U-Value = 1.71 W/sq. m/K, The central curtain wall with single one way reflective glass has U-Value = 4.8 W/sq. m/K with solar heat gain factor (SHGF) value of 0.75.

6.4.4.2 WEST Façade

New building is an extension of the existing Descon world headquarters building. The new building is started at the eastern wall of the existing building. So the western wall of the new building is a dead wall attached with the eastern wall of the old building as indicated in the typical plan already discussed.

6.4.4.3 EAST Façade

Left side is the East elevation facing towards the J-Tech building (A). Like other elevations, Eastern side is also cladded with a combination of 1 ½” thick “Gutka” facing brick tile and paneled color Crete with gray Portland cement on opaque surfaces (Emergency stairs vertical shaft) and only 4.4% of the total façade, glass area is provided having a thickness of 5mm as shown in the [6.19][xix]

6.4.4.4 SOUTH Façade

The southern (Rear side) wall is following the angular plot line of the Descon estate. It is hardly 5' from the boundary wall. Keeping the same language 1 ½” thick Gutka facing brick is applied on the façade. Considering the hottest side minimum glazing is provided by the Architect. The glazed area is only 3.8% of the total area of the façade. The whole façade is based on RCC columns & 9” thick brick wall.

The 9” thick brick wall including 1 ½” thick facing brick Gutka has the U-Value = 1.71 W/sq. m/K, The central curtain wall with clear glass has U-Value = 4.8 W/sq. m/K with solar heat gain factor (SHGF) value of 0.75.

6.4.5 Floor Specifications with thermal Properties:

The floors in basements are 10” thick RCC slab with 2” PCC including hardener in basements. Lower Ground Floor is finished with floor tiles (Porcelain). The details of the floors/slabs are given in the s [6.20], [6.21] & [6.22] respectively.

6.4.6 BUILDING SERVICES

6.4.6.1 Lighting Design

The electrical engineering services are given by electrical consultant Mr. Naseem Rathore, M/s ECON Associates, Gulberge Lahore. Consultant has designed the lighting services following the standards with respect to nature of space & illumination requirements.

The design parameters used for lighting services are given in Table [6.5][xx]. Air-Conditioning loads are not included in the given loads.

Sr. #

Area Type

General Lighting

Task Lighting

Equipments Plug Load

w/sq.ft.

Office-General+Equipments+Serwer

2.5

3.0

3.1

Office (Executive/Private)

2.5

1.25

Conference/Meeting/Discussion

3.5

3.0

1.20

Corridors

0.10

Lobbies, Staircases, Lifts & waiting

0.70

0.10

0.30

Kitchens/Food Preparation

1.50

0.15

0.50

Toilets

1.1

0.10

0.2

Mechanical/Electrical Room

0.15

0.2

Parking Areas

0.25

0.1

Storage Spaces

0.75

0.1

Table 6.5 showing the lighting equipment loads on different activity areas of JDEL building

Source: M/s Econ Associates

6.4.6.2 HVAC Design Services

The Mechanical Engineering (HVAC) services are designed & executed by MIA Corporation. Basically this was a turnkey project for MIA Corporation.

HVAC Design parameters given below are collected from MIA Corporation later on these parameters are used to simulate the performance of the system.

6.4.6.2a HVAC Zones

ZONES.jpgThe HVAC zoning is according to the conditioned & non conditioned spaces of the building. The typical plan of the building is showing the conditioned & non-conditioned zones of the building as given in the [6.23].

Descon World Headquarters Source: M/s (Oh+A Design Works)

The area shown in beige color is the Conditioned space including

· Offices for all type including office equipment / photocopier room

· Conference / Meeting / Discussion rooms

· Entrance Lobbies / Staircase / Lift areas / Waiting Area

· Training Area

· Server Room

And the areas shown in green color is the Non-Conditioned spaces including

· Corridors

· Balconies

· Kitchens / Kitchenettes

· Toilet Blocks

· Storage Areas

· Mechanical / Electrical Rooms

· Car parking areas in Basements

6.4.6.2b Weekly Occupancy Schedule

The starting & closing times of the office indicate the occupancy hours of the spaces. Occupancies hour are directly related to the overall electric load of the building. The Occupancy hours of JDEL Building are given in Table 3.6[xxi].

Sr. #

Day

Starting Time

Closing Time

Break Hours

Remarks

Monday

9:00 a.m.

5:00 p.m.

1.00 pm-2.0 pm

In break hours the office equipment & lighting requirements decreased But the HVAC load remains same.

Saturday alternate On/off

Tuesday

9:00 a.m.

5:00 p.m.

1.00 pm-2.0 pm

Wednesday

9:00 a.m.

5:00 p.m.

1.00 pm-2.0 pm

Thursday

9:00 a.m.

5:00 p.m.

1.00 pm-2.0 pm

Friday

9:00 a.m.

01:30 p.m.

1.30 pm-3.0 pm

3:00 p.m.

5:00 p.m.

Saturday

9:00 a.m.

05:00 p.m.

1.00 pm-2.0 pm

Sunday

O F F

Table 6.6 showing the Occupancy Schedule on weekly basis of JDEL Building

Source: M/s MIA Corporation

6.4.6.2c Cooling & Heating Set points

Cooling & heating set points (thermostat set temperatures) are concerned with the least requirement of comfort conditions for the internal spaces in a building, during occupancy & non-occupancy hours. The design parameters also include the cooling & heating set points (Design temperatures) at source/supply. The minimum flow of air in CFM (Cubic foot per minute) is also required. Set points regarding heating & cooling are listed in Table 6.7[xxii]. These temperatures will change according to the climatic conditions.

THERMOSTAT SET POINTS

Sr. #

Description

Occupied

Unoccupied

Cooling Set Points

76 Deg F

82 Deg F

Heating Set Points

70 Deg F

64 Deg F

DESIGN TEMPERATURES

Indoor

Supply

Cooling Set Points

75 Deg F

55 Deg F

Heating Set Points

72 Deg F

95 Deg F

Minimum Design Flow

2.0 cfm/ft. sq.

Table 6.7 showing the different temperature set points for JDEL Building

Source: M/s MIA Corporation

6.4.6.2d Design Occupancy of Spaces per person

The table 6.8[xxiii] given on the next page explains different areas with their occupancy and design ventilation rate.

Sr. #

Area Type

Design Max. Occupancy sft/Person

Design Ventilation cfm/person/ft.sq.

Office-General

Office (Executive/Private)

Conference/Meeting Rooms

27.5

Corridors

Lobbies, Staircases & Lifts

Kitchens/Food Preparation

Toilets

Mechanical/Electrical Room

210

Parking Areas

135

Storage Spaces

130

Table 6.8 showing % of different space, design ventilation air flow /person/sft

and design maximum occupancy, Source M/s MIA Corporation

6.4.6.2e HVAC Equipment Description

Heating system (Radiant Heating System)

In JDEL building “Radiant Heating system” is used for space heating.

An electrical conductor that offers resistance to the flow of electricity generates a certain amount of heat; the amount of heat generated is in direct proportion to the degree of resistance. This method of generating heat is employed in radiant heating systems.

The conductor used in radiant heating systems is an electric heating cable embedded in the ceilings. The cables may be installed at the site (as is often the case with new construction), or they may be obtained in the form of prewired, factory-assembled, panel-type units. The heat generated by the cables is transferred to the occupants and surfaces in the room by low-intensity radiation.

Radiant ceiling heating systems are by far the most commonly used type. The electric heating cables are activated and controlled by wall-mounted, low-voltage or line thermostats.[xxiv]

Cooling system (Chilled Water Coils)

6.5 Analysis of Results

· Envelope of the Building

· Interior Lighting

· HVAC

6.5.1 Annual / Monthly Energy Consumption

The Result shown in [6.24][xxvi] is concerned with energy consumption on monthly basis during the whole year. The result shows the change in energy demand with the change in climatic conditions of the environment.

6.5.2 Area General & Task Lighting

The lighting loads including general lighting (yellow color), task lighting (brown color) & office equipment (green color), loads almost remains constant throughout the year consuming an average electricity (52.5x1000 KWh area lighting, 82x1000 KWh task lighting & 47.5x1000 KWh equipment) as shown in the [6.24]. It reveals the fact that in office buildings, day lighting is not used for illumination purpose by putting vertical blinds on the windows and glazed fix panels.

6.5.3 Space Cooling & Heating (HVAC)

In the [6.24] cooling loads (blue color) are varying with the change in climatic conditions throughout the year in Lahore. The maximum cooling load of (78.25x1000) is observed during the month of May due to maximum outdoor temperature 45 Cº to 47 Cº. On the other hand in February space cooling load is comparatively low (38.55x1000) KWh.

The space heating loads (red color) having maximum value of (0.5x1000) KWh are observed during the month of December. The minimum requirements of heating loads are observed during the month of January (0.2x1000 KWh).

6.5.4 Ventilation

For the unconditioned area like car parking, storage areas, toilets, kitchenettes & mechanical / electrical rooms the minimum air flow requirement is 2.0 cfm/person/sft. This air flow will be achieved by using ventilation fans (magenta color) as shown in [6.24]. The maximum energy loads of (14.15x1000 KWh) are coming during the month of June.

6.5.5 Office Equipment

Generally in office building the office equipment load remains almost constant throughout the year, which is quite visible (Green color) from the results in Fig [6.24], In JDEL office the working conditions remains same for the whole year with a uniform load of (46x1000.KWh).

6.5.6 Total Energy Consumed

The result shown in Fig [6.25] indicates the total yearly energy (%) consumed in space cooling, heating, area general lighting, task lighting, office equipment and Ventilation.

The space cooling & heating systems are consuming about 24% of the total energy. While area lighting and task lighting is consuming 53% of the total energy that is very significant.

6.5.7 Total Energy Consumed

The result shown in (6.27) is related to the monthly energy bills of the energy consumed. It could be analyzed from result sheet no.1 & 2 (Fig 6.24, 6.25) that the energy demand is varying throughout the year with the change in climatic conditions. The bar chart shows that in February the energy demand is minimum during the whole year (430.7x1000) KWh which is 6.98% of the total energy consumed. On the other hand in May the energy requirements (554.4x1000) KWh is maximum throughout the year, which is 8.98% of the total energy consumed.

6.6 Comparison of Results

This section provides a comprehensive comparison of results between the two case studies already discussed regarding the energy consumption. The Table [6.9] is given below to give a consolidated picture of the energy consumption in each building.

SR. #

Area of Energy Consumption

Bank of Punjab Tower

JDEL Building

Area Lighting

25%

21%

Task Lighting

28%

32%

Space Cooling

29%

24%

Space Heating

01%

0.1%

Office Equipment

13%

19%

Ventilation

04%

3.9%

Tab. 6.9 Comparison of Energy consumption in BOP Tower & JDEL Building

The table [6.9] is explaining the percentage consumption of energy in different space. It is visible from the table percentage values that the energy consumption trend in both building is same. This similarity in consumption trend is due to the fact that both buildings are similar in nature “Office building”, situated in the same climatic zone of Pakistan, but different with respect to foot print, scale, height, number of stories, envelope specifications and design conditions.

6.6.1 Interior Lighting & Office Equipment

In both buildings the interior lightings loads including general & task lighting are almost same, reflecting the same design conditions formulated by Engr. Naseem Rathore, (M/s Econ Associates).

In JDEL Descon WHQ building the Architect has designed the general office spaces by giving a minimum area of 55sft/person as compared to area provided in BOP tower which is 70sft/person. It has increase the office occupancy per person in JDEL building. Resultantly there we find an increase in task lighting (32%) of JDEL building as compared to BOP tower which is (28%) shown in the table [6.9]. Similarly the equipment load will also be increase to 19% in JDEL building as compared to in BOP tower which is 13%.

6.6.2 Space Cooling & Heating (HVAC)

According to the comparison shown in table [6.9], in JDEL building the cooling load is 24% which is lower than cooling load in BOP tower which is 29% of.

Cooling loads are related to the thermal effectiveness of the envelope. If we compare the envelopes of both the buildings it is clear that in BOP tower the envelope is not properly designed according to the climatic conditions of the Lahore. The Building-A (BOP) envelope has three facades with curved curtain walls with one way reflected glass (S-E 44.1%, E-N 46.0%, S-W 46.5% & N-W 8.5%).

On the other hand in Building-B (JDEL), three facades are exposed to climate. Western side is a blank wall, adjacent to the existing Eastern wall of the Descon WHQ building. The Northern side has the maximum glazed area (47.3%) with clear glass. The Southern & Eastern sides have minimum glazed area of 3.8% & 4.4% respectively. Resultantly in building-B (JDEL) the cooling loads are comparatively low (24%) as compared to in building-A (BOP) which is 29%.

In both buildings the blue blocks are showing the cooling loads which are varying with the change in climatic conditions throughout the year in Lahore. According to the Fig 6.12 & 6.24, the cooling loads are rising towards the month of May & June in both buildings, due to outdoor maximum temperature of 47-48 Cº.

6.6.3 Ventilation

In BOP tower & JDEL the unconditioned area like car parking, storage spaces, toilets, kitchenettes & mechanical/electrical rooms the minimum ventilation requirements are reflecting the similar energy consumption trend of 3.9% - 4% in both buildings.

6.7 Comparison with International Energy Conservation Codes 2009

Reference to International Energy Conservation Code “ICC, IECC” year 2009, the building envelope should meet the fulfillment of different parameters according to the requirements of ASHRAE/IESNA Standard 90.1, Energy Standard for Buildings). These standards are concerned with the thermal properties of the construction materials, fenestration percentages of the envelope & lighting design parameters, listed below;

· U-Values

· R-Values

· Area of Fenestration (Glazing)

· SHGC Factor (Solar heat gain coefficient)

· Lighting Density

Sr. #

Building Elements

Code “IECC”

year 2009[xxvii]

Building A

(BOP)

Building B

(JDEL)

U-Value

W/m.sq.K

R-Value

m.sq.K/W

U-Value

W/m.sq.K

R-Value

m.sq.K/W

U-Value

W/m.sq.K

R-Value

m.sq.K/W

Roofs

0.048

20.833

0.70

1.43

0.72

1.40

Walls above Grade

0.123

8.13

1.49

0.67

1.55

0.65

Walls Below Grade

1.140

0.877

1.71

0.59

1.71

0.59

Floors

0.107

9.345

1.54

0.65

1.75

0.57

Curtain Wall

0.60

1.666

4.8

0.208

4.8

0.208

Entrance door

0.90

1.111

5.56

0.18

5.56

0.18

SHGC

0.35 (Max. value is 0.87)

0.75 (Max. value is 0.87)

Fenestration

>40%

46.5% with U-value 4.8

47.3% with U-value 4.8

Lighting density

G. Lighting

T. Lighting

G. Lighting

T. Lighting

G. Lighting

T. Lighting

1.0 w/ft.sq

3.0 w/ft.sq

3.5 w/ft.sq

2.5 w/ft.sq

3.0 w/ft.sq

Tab-6.10 “The comparison between International Energy Conservation Code 2009 & the parameters used in both case studies”

6.7.1Lighting Density

It is clear from the results that the main area of energy consumption in both cases is the interior lighting including area lighting & task lighting. The sum of task & area lighting in both buildings is 53% each.

After analyzing the design parameters, the intensity of area lighting and task lighting (3.0 to 3.5 Watts/sft) are responsible for 53% energy consumption in each case study. According to the Code “IECC” year 2009, the maximum allowable lighting load for both area & task lighting is 1.0W/sft. But in the case of BOP (Bank of Punjab tower), the area lighting is designed on 3.0W/sft and task lighting is consuming 3.5 W/sft as given in the table Tab-6.10, Similarly in JDEL building the energy loads of task lighting and area lighting are designed on 3.0 W/sft & 2.5 W/sft respectively as shown in the table Tab-6.10.

By following the Code “IECC” year 2009 we can reduce 70% lighting loads in BOP tower, similarly in JDEL we can save 64% energy consumed by the interior lighting.

6.7.2The Envelope & Cooling Loads

Envelope is the separation between the interior and the exterior of a building. It serves as to protect the interior conditions from the outer environmental forces by controlling the thermal values of the outer shell. These thermal values change with the variation in climatic conditions. These values have already defined as a design guidelines for energy conservation. In table 6.10 envelope guidelines are given by discussing the thermal properties of walls, roofs, fenestration & floors.

If we compare the thermal properties of walls above & below grade, slabs and fenestration area, we come to know that in BOP & JDEL no design guidelines are followed to address the energy issues caused by local climatic conditions. So there would be an increase in cooling loads. According to the Code “ IECC” year 2009, the maximum allowable fenestration is 40% of the wall surface area with glass u-value 0.3 W/m.sq.K. But in both case studies the fenestration is 46.5% in BOP & 47.3% in JDEL respectively.

6.7.3SHGC Factor (Solar heat gain coefficient)

The fraction of external solar radiation that is admitted through a window directly transmitted, and absorbed and subsequently released inward. The solar heat gain coefficient (SHGC) has replaced the shading coefficient (SC) as the standard indicator of a window's shading ability. SHGC is expressed as a number between 0 and 0.87. The lower a window's SHCG, the less solar heat it transmits, and the greater it's shading ability. SHGC may be expressed in terms of the glass alone or may refer to the entire window assembly.

To reduce the SHGC, manufacturers can apply a spectrally selective low-E (low-emissivity) coating to glazing as directed by Code “ICC, IECC” year 2009. This type of low-E coating can reduce the cooling load in the summer. Reflective coatings and tinted glass can also help reduce the SHGC.

In both case studies no low-E (low-emissivity) coating is applied to the fenestration to reduce the values of SHGC (0.75). The value 0.75 of SHGC means the solar heat gain is 75% through the glass. According to Code “ICC, IECC” year 2009, the maximum value of SHGC should not be greater than 0.35, mean maximum 35% solar heat gain through the glass.

[i] Drawing taken from M/s Imtiaz Ali & Associates (Consultant), June 2009

[ii] Section taken from M/s Imtiaz Ali & Associates (Consultant), June 2009

[iii] Drawing taken from M/s Imtiaz Ali & Associates (Consultant), June 2009

[iv] Image Taken from M/s Imtiaz Ali & Associates, June 2009

[v] Image Taken from M/s Imtiaz Ali & Associates, June 2009

[vi] Image Taken from M/s Imtiaz Ali & Associates, June 2009

[vii] Table/values taken from M/s Econ Associates

[viii] Drawing taken from M/s Imtiaz Ali & Associates (Consultant), June 2009

[ix] Table/Values taken from M/s MIA Corporation, June 2009.

[x] Table/Values taken from M/s MIA Corporation, June 2009.

[xi] Table/Values taken from M/s MIA Corporation, June 2009.

[xii] James E. Brumbaugh, HVAC Fundamentals, Volume 3, Page 417, 2004

[xiii] Result sheet explain the monthly energy consumed in BOP tower by EQuest

[xiv] Result sheet explain the monthly energy consumed in BOP tower by EQuest

[xv] Result sheet explain the energy bills on monthly basis in BOP tower by EQuest

[xvi] Image Taken from (Oh+A) Design Works, June 2009

[xvii] Image Taken from (Oh+A) Design Works, June 2009

[xviii] Image taken from M/s (Oh+A) Design Works

[xix] Image taken from M/s (Oh+A) Design Works

[xx] Table/values taken from M/s Econ Associates

[xxi] Table/Values taken from M/s MIA Corporation, July 2009.

[xxii] Table/Values taken from M/s MIA Corporation, July 2009.

[xxiii] Table/Values taken from M/s MIA Corporation, July 2009.

[xxiv] James E. Brumbaugh, HVAC Fundamentals Volume 1, Page 258, 2004

[xxv] James E. Brumbaugh, HVAC Fundamentals Volume 3, Page 410, 2004

[xxvi] Result sheet explain the monthly energy consumed in JDEL by EQuest

[xxvii] International Energy Conservation Code, Table 502.3, 505.5.2, Page 41,59 Jan 2009

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