The Impact of VISIONWALL High Performance Windows on the Northern Telecom Building in Ottawa, Ontario

Transcription

1 The Impact of VISIONWALL High Performance Windows on the Northern Telecom Building in Ottawa, Ontario Visionwall Technologies Inc Avenue Edmonton, Alberta, Canada T5V 1B4 Tel: Fax: prepared by Donald E. Holte, P.Eng. September 22, 1997

2 The Impact of VISIONWALL High Performance Windows on The Northern Telecom Building in Ottawa, Ontario T A B L E O F C O N T E N T S PAGE SUMMARY PREAMBLE 1.1 SCOPE WINDOW DATA DERIVATION ANALYSIS METHODOLOGY RESULTS 2.1 COOLING PLANT SIZE HEATING PLANT SIZE ANNUAL ELECTRIC POWER CONSUMPTION PEAK ELECTRIC POWER DEMAND ANNUAL NATURAL GAS CONSUMPTION ECONOMICS ENVIRONMENTAL IMPACT BUILDING DATA 5.1 PHYSICAL SHAPE AND SIZE USE AND OCCUPANCY SCHEDULE CONSTRUCTION INTERNAL LOADS HVAC SYSTEMS WINDOW PERFORMANCE DATA TABLE Northern Telecom Building, Ottawa, Ontario 1

3 SUMMARY - Note: this report for Blocks, A, B, C and 2 connecting links Modern high performance windows allow buildings to be built with almost unlimited window area and still comply with building energy efficiency standards such as ASHRAE Standard These new high performance windows are also economically attractive as their use results in substantial reductions in heating and cooling plant size and cost and building energy consumption and demand. The following presents the data derived from a study of a modern office building with electric cooling and natural gas heating systems. 2

4 1. PREAMBLE 1.1 SCOPE The information that follows in this case study shows the impact that VISIONWALL high performance windows have on an electrically cooled, natural gas heated office type building. In the study the building performance was analyzed using two alternative window systems, namely: Double Glazed; low-e green tint glass VISIONWALL 3-element; low-e green tint glass Information on cooling plant size, heating plant size, electric power consumption, peak electric power demand and natural gas consumption is presented in graphical form. The intent is to give a sense of the order of magnitude of the reductions and savings resulting from the use of VISIONWALL high performance windows. Detailed analysis of building heating and cooling loads and energy use was done during the study and this information may be made available if requested. A brief view of the economical and environmental impact of the use of high performance windows is presented. 1.2 WINDOW DATA DERIVATION Window performance data, both double glazed and VISIONWALL, was derived using the Window 4.1 computer analysis software provided by the Windows and Daylighting Group, Building Technologies Program, Energy Environmental Division, Lawrence Berkeley Laboratory, University of California. ( see item 5.6 for details ) 1.3 ANALYSIS METHODOLOGY The building analysis was done with the TRANE TRACE 600 computerized analysis program using the Ottawa, Ontario weather data supplied with the program. 3

5 2. RESULTS 2.1 COOLING PLANT SIZE.1 Figure 1, below, shows the size of the cooling plant as a function of window type. The cooling plant size is shown in kw. The word plant refers to all of the air supply, air return and distribution systems as well as to the chillers, cooling towers, chilled water piping and pumps, etc. Figure 1 Cooling Plant Size Northern Telecom Buildings in Ottawa, Ontario.2 As can be seen, in Figure 1, the use of VISIONWALL 3-element windows resulted in a significant reduction in the cooling plant size..3 With building cooling plants having an overall capital cost of $ per kw, a saving of approximately 570 kw can mean a substantial building first cost reduction. 4

6 2.2 HEATING PLANT SIZE.1 Figure 2, below, shows the heating plant size required as a function of window type. Figure 2 Heating Plant Size.2 While the reduction in heating plant size is significant ( 30% ) and will certainly result in reduced building capital cost, what is not apparent is the initial capital cost reduction that results from the elimination of any form of perimeter heating system. Perimeter heating systems are not required in a VISIONWALL building in a location with a winter outdoor design temperature such as that being analyzed in this study. The indoor glass surface temperature of the VISIONWALL windows will be above approximately +16ºC at all times thus eliminating cold glass down draft problems and ensuring a near symmetrical thermal enclosure. 5

7 2.3 ANNUAL ELECTRIC POWER CONSUMPTION.1 Figures 3 and 4, at the right, show the building s annual and monthly electric power consumption as a function of window type..2 The building electric power consumption is less when VISIONWALL high performance windows are used. This is as would be expected as the VISIONWALL windows have a lower shading coefficient and a much lower overall heat transfer coefficient resulting in a reduction in cooling energy consumption. Figure 3 Annual Electric Power Consumption Office and Data Center Building Figure 4: Monthly Electric Power Consumption Northern Telecom Buildings 6

8 2.4 PEAK ELECTRIC POWER DEMAND.1 Figures 5 and 6, at the right, show the building s annual and monthly peak electric power demand as a function of window type..2 The use of VISIONWALL windows reduced the peak electric power demand by approximately 11%..3 The peak electric power demand for both window types occurred in the summer months. This is as expected as that is when the building cooling load peaks, and the building air conditioning ( cooling ) system utilizes electric motor driven refrigeration equipment. Figure 5 Peak Electric Power Demand Northern Telecom Buildings Figure 6 Peak Monthly Electric power Demand Northern Telecom Buildings 7

9 2.5 ANNUAL NATURAL GAS CONSUMPTION.1 Figure 7, below, shows the building s annual natural gas consumption as a function of window type. Figure 7 Annual Natural Gas Consumption Northern Telecom Buildings in Ottawa, Ontario.2 The use of VISIONWALL high performance windows reduced the annual natural gas consumption by about 7500 GJ, or 55%. 8

10 3. ECONOMICS 3.1 CAPITAL COST The information in the table below compares the cost of a building built using a conventional double glazed window system with the same building built using a VISIONWALL 3-element high performance window system. The double glazed window building requires perimeter baseboard convectors to achieve acceptable space comfort conditions. The VISIONWALL window building with its warm indoor glass surface temperature does not require perimeter heating. Cost Item Curtain Wall Type Windows, Skylight, Curtain Wall Heating System Perimeter Heating Boilers, Pumps, Piping, etc Cooling & Ventilation Electrical System Double Glazed Low-E Green Tint Glass Standard Aluminum Frame 97,000 ft² x $40/ft² = $3,880, m x $200/m = $600,000 63,000 m² x $13/m² = $819, kw x $560/kW = $1,965,600 2,054 kw x $200/kW = $410,800 VISIONWALL 3-Element System Low-E Green Tint Glass High Performance Aluminum Frame 97,000 ft² x $43/ft² = $4,171, % x $819,000 = $368, kw x $560/kW = $1,646,400 1,819 kw x $200/kW =$363,800 Total Comparative Capital Cost $7,675,400 $6,549, ENERGY COST As shown in items 2.3 and 2.4, VISIONWALL high performance windows significantly reduce annual electric power consumption and demand and natural gas consumption. The building using the VISIONWALL 3-element window system used approximately 67,483 kwh of electric power and 7,480 GJ of natural gas per year less than the building using conventional double glazed windows. If electric power costs $0.14/kWh, and natural gas costs $8.00/GJ, this would result in a saving of $69, per year; then assuming a 6% discount rate and a 50 year life, the Net Present Value of this energy saving is $1,092,

11 4. ENVIRONMENTAL IMPACT The use of VISIONWALL high performance windows results in significantly reduced building energy consumption as shown in items 2.4 and 2.5. This reduced energy consumption has a definite positive impact on the outdoor environment. In the United States, each kwh of electric power consumed results in the addition of about 0.68 kg of CO 2, kg of SO 2 and kg of NOx to the atmosphere. Each Therm (105.5 MJ) of building heat energy provided by a natural gas fueled heating boiler results in the addition of about 6.5 kg of CO 2 to the atmosphere. The building with the VISIONWALL high performance window system consumed approximately 67,483 kwh per year less electric power and requires about 7,480 GJ per year less heat energy. This reduction in electric power and building heat energy ( natural gas ) consumption will, over the life time of the building, result in greatly reduced emissions, as shown in the following table. Reduction In Contaminant Release Time CO 2 SO 2 NOx 25 Years 50 Years kg ( 12.7 tonnes ) kg ( tonnes ) kg ( 11.5 tonnes ) kg ( 23 tonnes ) kg ( 3.9 tonnes ) kg ( 7.8 tonnes ) 10

12 5. BUILDING DATA 5.1 PHYSICAL SHAPE AND SIZE Floor Area = 63,000 m² (excluding sub-grade level) 5.2 USE AND OCCUPANCY Office; occupied Monday thru Friday 5.3 CONSTRUCTION Frame: Steel Walls: Opaque areas; U = 0.08 Btu/hr-ft²-ºF Window U = see Window performance Table, item 5.6 Floors: Concrete, carpet cover Roof: B.U.R. with rigid insulation U = 0.05 Btu/hr-ft²-ºF 5.4 INTERNAL LOADS People: Lights: Misc. Electrical: 1 person per 250 ft² gross floor area 1.57 W per ft² gross floor area 0.75 W per ft² gross floor area 5.5 HVAC SYSTEMS Variable air volume ( VAV ) with hot water reheat and perimeter baseboard convectors 2 stage air cooled centrifugal water chiller Variable speed drive centrifugal air foil supply and return fans; 100% outside air economizer Heating: hot water; natural gas fueled hot water boiler 5.6 WINDOW PERFORMANCE DATA TABLE Alternate Number 1 2 Window Type Double Glazed Green Tinted Glass VISIONWALL 3-element Green Tinted Glass Overall U Value ( glazing unit + frame ) Btu / hr-ft²-ºf Shading Coefficient Visible Light Transmission % % 11