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ENERGY AUDIT
Project :
Industrial building United Arab Emirates (Case study)
Contact person (DERBIGUM): Leonard Fernandes DERBIGUM project reference : UAE -2014 - EA 103 Author : Daniel Heffinck (DERBIGUM) Date : 14/04/2014
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 2
Energy audit and dynamic simulation software conceived with the scientific collaboration of
3E sa (Headquarters) – Rue du canal 61 – B1000 Brussels 3E France (Branch) – 8, rue Maréchal de Lattre de Tassigny – F59000 Lille 3E France (Office) – 80 Bd. du Maréchal Leclerc – F31000 Toulouse
www.3E.eu
ENERGY AUDIT
Project :
Industrial building United Arab Emirates (Case study)
Contact person (DERBIGUM): Leonard Fernandes Regional Head M: +971 50 727 6787 E: [email protected]
DERBIGUM MIDDLE EAST 709, Al Thuraya Tower 2 | Dubai Media City | P.O Box 500717 Dubai, UAE
www.derbigum.com DERBIGUM project reference : UAE -2014 - EA 103 Author : Daniel Heffinck (DERBIGUM) Date : 14/04/2014
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 3
Thermal and energy Audit
DERBIBRITE NT® flat roof
1. PREAMBLE
1.1 INTRODUCTION
DERBIGUM introduced DERBIBRITE NT on the market of flat roofs as a « passive cooler » solution with a high emissivity and reflectance for flat roofs, in order to reduce the cooling demands or to increase the interior comfort during hot periods in service or industrial buildings.
3E is an engineering & consulting company, specialized in energy savings and renewable energies. The active involvement in international projects and in the development of research activities allows 3E to guarantee a high level of knowledge in technological innovations. Due to its activities in the field of energetical efficiency in buildings, 3E developed a unique expertise in the use of thermal dynamic simulation software for buildings and in the development of tools.
In order to evaluate the energetical and thermal benefits provided by DERBIBRITE NT, 3E developed a dynamic simulation tool allowing to calculate the energetical demands of a building. Furthermore, this tool allows DERBIGUM to evaluate quantitatively the effect of DERBIBRITE NT on every building complying with the basic criteria.
1.2 PRESENTATION OF THE METHOD
A complete and detailed analysis of the thermal behaviour of a building requires a specific attention that often resorts to using computer simulations (thermal dynamic simulation software ).
The tool developed by 3E for this project is based on the TRNSYS software, worldwide considered as reference tool for thermal dynamic simulations of energetical systems and buildings.
The tool created for this project allows to simulate, hour by hour, the thermal transfers from the building taking into account the exterior climatic conditions of the site (temperatures, sun radiation, wind speed, …) and the characteristics of the building (internal benefits, composition of walls, heating, cooling…).
Various temperature results, energetic needs, or other figures can be edited for every hour during the year.
Certain hypotheses have been adopted in order to simplify for example the building geometry, however without modifying the accuracy of the results.
Additional information regarding the software and the used numeric model can be found in the appendix.
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 4
2. PRESENTATION OF THE PROJECT
This case study concerns an industrial building, located in the United Arab Emirates.
The present document groups the thermal results obtained by digital simulation of the existing modelized situation compared with the projected situation improved by means of the passive cooler DERBIBRITE NT.
The data and hypotheses for the simulation are indicated in the present document.
This study is presented as an Energy Audit.
2.1 DESCRIPTION OF THE BUILDING
The project details used for the simulation are indicated below.
2.1.1 Main data of the building
Length building _____________________ 200 m
Width building _____________________ 50 m
Roof surface _______________________ 10.000 m²
Height ____________________________ 8 m
Roof slope 2 %
2.1.2 Characteristics of the roofs for the 2 situations (existing and projected)
Figure 1: Stratigraphy of the roof complex (reference)
Reference situation (typical roof) : inverted roof covered with concrete tiles
1. Concrete tiles.
2. Protection and sliding layer.
3. (XPS) Extruded polysterene.
4. Protection layer
5. Waterproofing layer.
6. Concrete deck.
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 5
Figure 2: Stratigraphy of the roof complex (alternative)
Alternative proposal : warm roof with uncovered DERBIBRITE NT waterproofing membrane
1. DERBIBRITE NT « passive cooler »
2. (PUR) Polyurethane or (PIR) Polyisocyanurate, glued by means of DERBITECH FA.
3. DERBIPRIMER S, bituminous primer .
4. Concrete deck.
Schedule 1 : Roof properties
Solar reflectance
Thermal emissivity
Typical inverted roof (estimation)
+/-15% 90%
DERBIBRITE NT alternative 81% 81%
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 6
2.1.3 Properties of walls for both situations
The walls have an identical composition in both the existing and the projected situation.
Each wall is characterized by its orientation, its composition, as well as by the importance of the « secondary » surfaces such as the doors (S2) and the windows (S1).
Schedule 2 : Wall properties
WALL 1 WALL 2 WALL 3 WALL 4
Orientation North East South West
Composition
Identical composition for all the walls : Corrugated aluminium sheet, PU 50 mm, interior finish
L1 [m] 50 200 50 200
H1 [m] 8 8 8 8
S1 [m²] 0 50 25 50
S2 [m²] - - - -
S1 (windows): double glazing ; surfaces are given as an example
S2 (doors): can be considered as negligible in comparison with the global opaque surface.
2.2 HYPOTHESES FOR USING CONDITIONS
� Interior using conditions: factory (light bench work), 90 W.
� Occupation of the building: production 6 days/ week; 2 shifts a day
� Air conditioning : day setting temperature 22°C, night setting temperature 26°C
� No mechanical ventilation
Schedule 3 : Properties of internal gains
Staff Lighting Computers Other
Maximal output [W/m²]
- 10 W not significant 5 W (*)
Occupation density [number of people]
50 persons - - -
(*) Estimated output from production equipment
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 7
3. RESULTS AND ANALYSIS
For the present audit study, we analysed 3 cases with distinct roof insulation levels.
The considered insulation levels are given in the table below.
CASE 1 CASE 2 CASE 3
Inverted roof (reference) XPS 50 mm XPS 80 mm XPS 100 mm
DERBIBRITE NT warm roof (alternative)
PU 50 mm PU 80 mm PU 100 mm
3.1 RESULTS CASE 1
3.1.1 COOLING DEMAND
Schedule : Monthly cooling demand , within the building considering the simulation of roof constructions as detailed below.
Comments :
� Reference (1st column) : represents the inverted roof construction (XPS 50 mm)
� Case 1 (2nd column): represents a warm roof construction with a light grey roofing material
(PU 50 mm)
� Case 2 (3rd column): represents a warm roof construction with DERBIBRITE NT (PU 50 mm)
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 8
3.1.2 RESULTS AND ANALYSIS : COOLING ENERGY SAVING
Summary of analysis (CASE 1)
Inverted roof
Warm roof solution with
DERBIBRITE NT
Annual cooling energy demand
kWh/yr +/- 892.300 +/- 619.900
Annual energy saving kWh/yr 272.400
Cooling saving in percentage
% 30,53%
3.2 RESULTS CASE 2
3.2.1 COOLING DEMAND
Schedule : Monthly cooling demand , within the building considering the simulation of roof constructions as detailed below.
Comments :
� Reference (1st column) : represents the inverted roof construction (XPS 80 mm)
� Case 1 (2nd column): represents a warm roof construction with a light grey roofing material
(PU 80 mm)
� Case 2 (3rd column): represents a warm roof construction with DERBIBRITE NT (PU 80 mm)
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 9
3.2.2 RESULTS AND ANALYSIS : COOLING ENERGY SAVING
Summary of analysis (CASE 2)
Inverted roof
Warm roof solution with
DERBIBRITE NT
Annual cooling energy demand
kWh/yr +/- 752.700 +/- 562.900
Annual energy saving kWh/yr 189.800
Cooling saving in percentage
% 25,22%
3.3 RESULTS CASE 3
3.3.1 COOLING DEMAND
Schedule : Monthly cooling demand , within the building considering the simulation of roof constructions as detailed below.
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 10
Comments :
� Reference (1st column) : represents the inverted roof construction (XPS 100 mm)
� Case 1 (2nd column): represents a warm roof construction with a light grey roofing material
(PU 100 mm)
� Case 2 (3rd column): represents a warm roof construction with DERBIBRITE NT (PU 100 mm)
3.3.2 RESULTS AND ANALYSIS : COOLING ENERGY SAVING
Summary of analysis (CASE 3)
Inverted roof
Warm roof solution with
DERBIBRITE NT
Annual cooling energy demand
kWh/yr +/- 699.700 +/- 542.000
Annual energy saving kWh/yr 157.700
Cooling saving in percentage
% 22,54%
4. CONCLUSION
The results of this study, based on a numerical simulation, confirm the benefits and positive effect of the highly reflective DERBIBRITE NT membrane on the energetical balance of the building.
The DERBIBRITE NT clearly acts as a « passive cooler » when used as an exposed layer in a warm roof construction.
Considering the parametres and hypotheses considered for this study, the following savings on cooling energy consumption could be achieved with our proposed alternative roof construction, when compared to the reference inverted roof:
� CASE 1 (50 mm insulation) : energy saving of over 30%
� CASE 2 (80 mm insulation) : energy saving of over 25%
� CASE 3 (100 mm insulation) : energy saving of over 22%
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 11
5. DERBIBRITE NT – TECHNICAL SHEET
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 12
6. DERBIBRITE NT - PROJECT REFERENCES
YAMAHA European Distribution Centre (Netherlands) HENKELL Wiesbaden (Germany)
ABB (Italy)
SWATCH (Switzerland) PORSCHE (Italy)
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LAMBORGHINI (Switzerland) San Antonio City Hall (USA – Texas)
UN City (Denmark)
Exhibition and Convention Centre (Sweden) Life Care Hospital (USA)
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6. APPENDIX
A. GLOSSARY
What happens to the fraction of energy that is not reflected by the surfaces The solar energy that was not reflected is converted in heat that is dispersed and transfered under 3 forms: conduction , convection and radiation. The conduction and the convection generally lead the heat towards the interior air of the volume underneath the roof. The heat that is not dispersed via conduction and/or convection is radiated from the roof under the form of an infra-red radiation (lower range IR). This property of radiating the heat is called « emissivity ».
Energy Star ® ................................... An American program monitored by the Environmental Protection Agency (EPA), promoting the conservation of Energy and the natural resources associated with the production of energy.
Solar reflectivity ................................. Quantity of solar energy that a given material reflects towards the
atmosphere. The “Albedo” term is also used to define this effect. Usually expressed in %. The white surfaces offer the highest solar reflectivity, while the black ones the lowest. This is a surface property. It is measured according to the ASTM 1549 standards.
Thermal emissivity ............................. Quantity of energy that a given material emits due to its proper heat and temperature. Usually noted in %. This % of energy that was not reflected is radiated in the environment. This is a surface property. The higher the emissivity, the faster a given material is going to cool off by itself through radiation and the lesser heat will be transferred to the surrounding air through convection. The emissivity is measured according to the standard ASTM E 4308-71 method A.
B. PRESENTATION OF THE E-BRITE SOFTWARE
The tool developed by 3E is based on a scientific core TRNSYS, worldwide considered as the reference tool for thermal dynamic simulations of energetical systems and buildings. Various institutes, research organisms or companies use this software in order to study and validate the problems of the building’s physics.
TRNSYS (TRaNsient SYstem Simulation Program) is a modular simulation software. It is supplied with a number of basic modules (about 50) and it offers the possibility to the user to create himself his proprer components. Thanks to this modular approach, TRNSYS is extremely flexible to modelize thermal and energetical models according to different complexity levels.
These simulations are linked with:
� Exterior : meteorological conditions
� Interior: different scenarios of occupation
� The use of different kinds of energy
The tool created for this project allows to simulate, hour by hour, the thermal transfers from the building taking into account the exterior climatic conditions of the site (temperatures, sun radiation, wind speed, …) and the characteristics of the building (internal benefits, composition of walls, heating, cooling…).
Various temperature results, energetical needs, or other figures can be edited for every hour during the year.
Certain hypotheses have been adopted in order to simplify for example the building geometry, however without modifying the accuracy of the results.
DERBIGUM – Bergensesteenweg 32 – B-1651 LOT – T. +32 (0)2 334 87 00 – F. +32 (0)2 378 14 69 – [email protected] - www.derbigum.com 15
C. VALIDATION OF E-BRITE SOFTWARE
In order to validate the results generated by the E-BRITE software, various test-cases have been studied by the engineering office 3E and compared with the VIRTUAL ENVIRONMENT software, other reference software in the field.
The results have demonstrated the reliability of the model based on TRNSYS, and the minor differences are due to the different approach of hypotheses in the calculation method.
D. INTERPRETATION OF THE RESULTS OF THE AUDIT
This « roof » audit is based on information received on the building structure, thermal conditions, the conditions of use and technical equipments. As specific information may be missing or might be subject to interpretation, it is occasionally necessary to calculate with hypotheses. Furthermore, the simulation software cannot always take account of all the different segments in a building nor consider specific or irregular shapes.
As a result, the conclusions of this energy audit have to be considered as indicative.
