riga technical university institute of heat, gas and water technology office building night cooling...
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![Page 1: Riga Technical University Institute of Heat, Gas and Water technology OFFICE BUILDING NIGHT COOLING POTENTIAL IN BALTIC REGION RENARS MILLERS, ALEKSANDRS](https://reader035.vdocument.in/reader035/viewer/2022062423/56649eda5503460f94be9a59/html5/thumbnails/1.jpg)
Riga Technical UniversityInstitute of Heat, Gas and Water technology
OFFICE BUILDING NIGHT COOLING POTENTIAL IN BALTIC REGION
RENARS MILLERS, ALEKSANDRS ZAJACS, ARTA USELONOKA.
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General information:
Location – 56.97° N, 24.07° E(Riga),
Site– outside city centre, surrounding agglomeration 2-4 storey buildings
Model ground area - 662m2 Volume – 14214m3 Height – 6 storeys, 24m
Envelope/volume ratio (Net) – 0.24m2/m3 Envelope/volume ratio (Gross) – 0.25m2/m3 Window/envelope ratio – 32%
Solar protection – standard glazing + shading devices
Cooling technique – Mechanical cooling + night cooling
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The lowest possible area/volume ratioCan be expressed as - 3/r
A/V ratio of a sphere with the same volume – 0.2
Starting point – the form
Sphere
If h=D then A/V ratio can be expressed as - 3/r
A/V ratio of a sphere with the same volume – 0.22
Cylinder
A/V ratio – 0.25
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Window description:
•U - value - 1.2W/m²K;•G - value - 0.62;•Tsolar - 0.54;•Tvisible - 0.8;
Description of external constructions:
•External wall - 0.14W/m²K;•Roof - 0.12Wm²K;•External floor - 0.33W/m²K;•Air tightness - 0.6ACH at 50Pa; Concrete building body and
slabs help to achieve greater thermal mass for accumulating heat during occupied hours.
Building envelope
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Night cooling – predicted air movement
Predicted air exchange rate – 5 ACH
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Simulated air exchange rate – 7.9 ACH, Indoor/Outdoor temperature difference – 10K, No wind present
Night cooling – simulated air movement
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The benefits of night cooling
Mechanical cooling
Mechanical cooling + night cooling
Absolute reduction
Relative reduction
Annual energy consumption for cooling, kWh/m²
17 8 -9 -53%
Peak load, kW 247 217 -30 -12%
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Simple shading design
No external shading devices With external shading devices
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Mechanical cooling Mechanical cooling + shading devices
Absolute reduction
Relative reduction
Annual energy consumption for cooling, kWh/m²
17 12 -5 -29%
Peak load, kW 247 197 -50 -20%
Benefits of shading devices
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Heat balance of typical room on the south side
No shading, no night cooling
Shading, night cooling
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Shading devices in combination with night cooling as passive cooling approach
Mechanical cooling
Mechanical cooling + night cooling
Mechanical cooling + shading devices
Mechanical cooling + shading
devices + night cooling
Absolute reduction
Relative reduction
Annual energy consumption for cooling, kWh/m²
17 8 12 4 -13 -76%
Peak load, kW 247 217 197 138 -109 -44%
Reduction from night cooling – 30kW
Reduction from shading devices – 50kW 80kW
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Conclusions:• Stack effect can boost air exchange rate during night cooling in multi-
storey building• Night cooling in this case is more effective for reducing energy
consumption – 53%• Shading devices are more effective to reduce peak load – 20%• Significant reduction of pike load – 44% can be achieved when using both
– night cooling and shading design in combination.
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Thank you for your attention!