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Riga Technical University Institute of Heat, Gas and Water technology

OFFICE BUILDING NIGHT COOLING POTENTIAL IN BALTIC REGION. Riga Technical University Institute of Heat, Gas and Water technology. RENARS MILLERS, ALEKSANDRS ZAJACS, ARTA USELONOKA. General information: Location – 56.97 ° N, 24.07° E (Riga), Site – outside city centre,

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Riga Technical University Institute of Heat, Gas and Water technology

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  1. OFFICE BUILDING NIGHT COOLING POTENTIAL IN BALTIC REGION Riga Technical University Institute of Heat, Gas and Water technology RENARS MILLERS, ALEKSANDRS ZAJACS, ARTA USELONOKA.

  2. 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

  3. Starting point – the form Sphere The lowest possible area/volume ratio Can be expressed as - 3/r A/V ratio of a sphere with the same volume – 0.2 Cylinder 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 A/V ratio – 0.25

  4. Building envelope • 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. • Window description: • U - value - 1.2W/m²K; • G - value - 0.62; • Tsolar - 0.54; • Tvisible - 0.8;

  5. Night cooling – predicted air movement Predicted air exchange rate – 5 ACH

  6. Night cooling – simulated air movement Simulated air exchange rate – 7.9 ACH, Indoor/Outdoor temperature difference – 10K, No wind present

  7. The benefits of night cooling

  8. Simple shading design No external shading devices With external shading devices

  9. Benefits of shading devices

  10. Heat balance of typical room on the south side No shading, no night cooling Shading, night cooling

  11. Shading devices in combination with night cooling as passive cooling approach Reduction from night cooling – 30kW Reduction from shading devices – 50kW 80kW

  12. 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.

  13. Thank you for your attention!

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