Gestão de Energia Energy audits

1. Gestão de EnergiaEnergy audits Carlos A. Santos Silva Professor Associado Convidado Cátedra WS – Energia Departamento de Física carlos.santos.silva@tecnico.ulisboa.pt

2. Outlook • Energy Audit • Energy Services • Energy Efficiency Measures • Measurement and Verification

3. Energy Audit

4. Overall objectives • Detailed analysis of the energy use in a certain equipment, activity, installation , building, campus: • Where energy is used • When energy is used • How energy is used • Through an audit it is possible to: • identify/model the required energy services • Design a solution to improve the energy use and supply • Equipment replacement, process change, user behaviour change

5. Energy Audit Phases • Preparing and Planning • Facility inspection • Field Work • Data analysis • Energy audit reporting • Energy Action Plan

6. Action Plan • An action plan is a strategy plan to increase the energy efficiency of the facility • It describes the solutions • It describes the efficiency objectives • It describes the implementation plan • This plan results from the energy audit

7. Preparation and planning

8. Tasks • Collect data regarding energy use • Energy bills (3 or more years if available) • Collect data regarding building envelope and equipment's • Location and weather data • Building description (blueprints, bill of materials, etc.) • Characteristics of the main equipment's • Functional organization • Preliminary data analysis • Find any awkward result

9. Preliminary visit • Visit together with the facility manager to see how the facility operates • Collect missing data (if available) • Observe the building envelope • Identify “low-hanging fruit” savings

10. Facility Characterization

11. Objective • Detailed analysis of the collected data • Evaluate energy consumption baseline (normalize climate data) • Prepare energy balance • Identify energy services • Characterize equipment's performance

12. Main Equipments • Heating and cooling • Hot water and steam boilers • Chillers and cooling towers • Ait treatment units • Ventilation units • Pumps and pipes • Air conditioning units • Air conditioning controllers • Hot Water • Tankers • Lighting • Lights • Ballasts • Controllers

13. Other Equipments • Elevators and other mechanical transportation systems • Specific equipment's of the building • Monitors in hospitals, TVs in restaurants • Refrigeration equipment's in kitchens , laundries, pools • Energy generation systems (solar, co-generation) • The efficiency of every heat generation system should be verified

14. Field Work Plan • With the collected data and the characterization of the facility, prepare the field work: • The list of equipments that will be measured • The list of equipments that needs to be used for measurement • The measuring procedure (one point measure, long data collection) • Interviews to be done to complete information

15. Field WORK

16. Main activities • Measure energy consumption of main sectors/equipments • Productive systems, hot water, heating and ventilation • Identify lack of maintenance • Verify electric installations • Verify HVAC and lighting controllers • Continuous monitoring or main consumption points of energy to obtain load diagrams • One day • One week

17. Complementary activities • Complementary measurements to collect information • Room temperatures • Room luminance • Characterize schedule of main equipments (interviews, observations) • Characterize the envelope in detail and how users interact with it (interviews, observations) • Characterize utilization patterns

18. Audit Equipment Thermo-hygrometer Thermometer Current Clamp Lux meter Network analysers Thermography

19. Data analysis

20. Objectives • Disaggregation of energy consumption by energy services • Complete energy balance • Develop load diagrams • Daily, weekly and if possible annual evolution • Evaluate energy indicators, specific consumptions • Deviation form disaggregation and indicators should provide hints regarding energy efficiency measures

21. Activities • Evaluate efficiency of the equipments and installations and estimate savings from equipment replacement, process change or behaviour change or installation of generation equipments • Evaluate technical feasibility of doing equipment replacement, process change of behaviour change • Due the economic evaluation of implementing such measures • Determine facility energy class

22. Energy balance • The energy balance disaggregation should be in an annual basis • Consider average consumption of the last 2/ 3 years, suing information from energy bills • Consider the information gathered in the audit • Equipment's use schedule • Equipment's characterization • Equipment's measurements • Simulation (software)

23. Simulation • Objective is to obtain the energy consumption considering the utilization, the equipments, the envelope • The model should be adjusted to the field measurements • The calibrated simulation will enable: • Testing different energy efficiency measures

24. Energy bills • Evaluate the average consumption across the year • With more than one year, the influence of weather of activity may be filtered • Verify correctness of tariffs • Evolution of used power • Impact of equipments or activity change

25. Audit report & Action Plan

26. Objective • Describe the energy demand of the installation and the costs • Describe the equipment status • Identify energy efficiency measures, the investment and its potential payback • Substitution or retrofit of equipment • Use of more efficient controllers • Installation of energy management systems • Introduction of renewable resources generation • Identify upcoming changes in regulations that may impact on the current energy use

27. Action Plan • From the different measures proposed in the energy audit, identify an implementation plan • Investment plan • Schedule • Low cost measures should be the first to be implemented • The return of investment period should be the indicator used to prioritize the measures in the plan • This should be done closely with the energy manager and the board

28. Gestão de EnergiaEnergy services Carlos A. Santos Silva Professor Associado Convidado Cátedra WS – Energia Departamento de Física carlos.santos.silva@tecnico.ulisboa.pt

29. Outlook • Space Heating and Cooling • Thermal balance • Heat transfer • Internal gains • Solar gains • Climate • Comfort • Insulation • Hot water • Cooking • Food Conservation • Lighting • Entertainment • Work • House keeping • Communication

30. Space heating (and cooling)

31. Thermal Balance (1) • Applying the 1st law of thermodynamics • Balance between all the gains and losses • Solar (S) • Internal(I) • Conduction, convection and radiation through envelope (T) • Air mass balance/ventilation (V)

32. Thermal balance (2) (-) Losses (+) Gains

33. Thermal balance – closed system (3) • 1st law of thermodynamics • Internal energy variation • Mass includes air, walls, furniture, etc… • Heat • Transfer through windows, walls, et… • Generation and absorption • Occupants • Appliances (work consumption) =

34. Thermal balance – open system (4) • 1st law of thermodynamics • Ventilation • Air leakages (infiltrations) - - -

35. Heat transfer gains • Conduction • Convection • Radiation

36. I) • Electric appliances • Computers • Heat generation in power sources, processor • Lighting • Radiation and convection • Occupants • Radiation, convection, latent heat (water vapour) We do not consider here the heat generation from radiators, fireplaces, AC

37. Energy generated by occupants

38. Solar gains • Heat Exchange with the sun • Direct (sunny days) • Diffuse (cloudy days) • Usually evaluated using the RTS (radiant time series method)

39. Air exchanges and leakages • Air Exchange between the interior and the exterior originates changes in the internal energy (and thus temperature)

40. Dynamic simulation Design Builder • It allows to evaluate all heat exchanges and calculates heating and cooling needs Open Studio

41. The influence of climate

42. Degree Days • Simple and direct method (though incomplete) to characterize the climate of a certain region • It measures the product between the number of days and the number of degrees that the interior temperature is lower (heating) or higher (cooling) than a certain comfort temperature • Heating degree days (HDD) • Cooling degree days (CDD)

43. HDD and CDD in Europe

44. Thermal comfort

45. Comfort temperature “mind state that expresses satisfaction about the thermal environment” • Human comfort depends on the ability to control the body temperature between 36 and 37ºC • It depends on the balance between heat exchange • It is not only about air temperature • It depends on the humidity (evaporation/transpiration) • It depends on the activity, clothes, etc…

46. Comfort conditions • Temperature: 20 to 27ºC • Relative humidity: 30 to 60%

47. Insulation

48. Thermal and air leakage insulation

49. Thermal bridges • It describes the disruption of the thermal insulation due to the existence of a material with high conductivity • They can represent up to 20% losses

50. Green roofs and facades • Adds width (L) with a fairlygood insulation • k: 0.18 a 0.41 W/mK • Concrete roof k=1.4 W/mK • Has impact on radiation and convection through latent heat