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Energy Management: 2013/2014 Energy in Buildings Prof. Tânia Sousa

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Presentation on theme: "Energy Management: 2013/2014 Energy in Buildings Prof. Tânia Sousa"— Presentation transcript:

1 Energy Management: 2013/2014 Energy in Buildings Prof. Tânia Sousa

2 Gestão de Energia Slide 2 of 53 Buildings account for 31% of global final energy consumption (20 to 40%) Energy Services? Energy Consumption in Buildings 1MWh=3.6GJ 16.45GJ 66.96GJ 34.70GJ

3 Gestão de Energia Slide 3 of 53 Buildings account for 31% of global final energy consumption (20 to 40%) Energy use in buildings: thermal confort, refrigeration, hygiene, nutrition, illumination, etc Energy Consumption in Buildings 1MWh=3.6GJ 16.45GJ 66.96GJ 34.70GJ

4 Gestão de Energia Slide 4 of 53 Energy Consumption in Buildings Final Energy use in buildings by fuel in 2007 in EJ –Differences? Residential Commercial & Public

5 Gestão de Energia Slide 5 of 53 Energy Consumption in Buildings Final Energy use in buildings by fuel in 2007 in EJ –Combustible and renewables is the most important fuel in residential buildings while electricity dominates comercial buildings Residential Commercial & Public

6 Gestão de Energia Slide 6 of 53 What about Portugal? –In 2007 the final consumption of services + domestic sector represented 29% of the final energy consumption –In 2007 the final consumption per capita was GJ which is 61.5% of the EU-27 –Electricity is 49% of the final energy used by buildings (68% in comercial and 36% in residential) Energy Consumption in Buildings

7 Gestão de Energia Slide 7 of 53 What about Portugal? –In 2007 the final consumption of services + domestic sector represented 29% of the final energy consumption –In 2007 the final consumption per capita was GJ which is 61.5% of the EU-27 –Electricity is 49% of the final energy used by buildings (68% in comercial and 36% in residential) –Do you think that the fraction of primary energy would be higher or lower? Electricity is 22% of total final energy Energy Consumption in Buildings

8 Gestão de Energia Slide 8 of 53 Energy Consumption in Buildings Most effective strategy to reduce energy use in buildings (Harvey, 2010): –Reduce heating and cooling loads through a high- performance envelope high degree of insulation, windows with low U values in cold climates and low solar heat gain in hot climates, external shading and low air leakage

9 Gestão de Energia Slide 9 of 53 Energy Consumption in Buildings Most effective strategy to reduce energy use in buildings (Harvey, 2010): –Reduce heating and cooling loads through a high- performance envelope high degree of insulation, windows with low U values in cold climates and low solar heat gain in hot climates, external shading and low air leakage –Meet the reduced load as much as possible using passive solar heating, ventilation and cooling techniques while optimizing the use of daylight

10 Gestão de Energia Slide 10 of 53 Energy Consumption in Buildings Most effective strategy to reduce energy use in buildings (Harvey, 2010): –Reduce heating and cooling loads through a high- performance envelope high degree of insulation, windows with low U values in cold climates and low solar heat gain in hot climates, external shading and low air leakage –Meet the reduced load as much as possible using passive solar heating, ventilation and cooling techniques while optimizing the use of daylight –Use the most efficient mechanical equipment to meet the remaining loads –Ensure that individual energy-using devices are as efficient as possible and properly sized

11 Gestão de Energia Slide 11 of 53 How much energy reduction can we achieve? –Passive house standard: heating 15kWh/m 2 per year cooling 15 kWh/m 2 per year TPE 120 kWh/m 2 per year n / hour Energy Consumption in Buildings

12 Gestão de Energia Slide 12 of 53 How much energy reduction can we achieve? Energy Consumption in Buildings Triple-glazed windows with internal venetian blinds & mechanical ventilation with 82% heat recovery

13 Gestão de Energia Slide 13 of 53 Heating needs decreased from 220 kWh/m 2 /year to 30 kWh/m 2 /year How much energy reduction can we achieve? Energy Consumption in Buildings Triple-glazed windows with internal venetian blinds & mechanical ventilation with 82% heat recovery

14 Gestão de Energia Slide 14 of 53 How much energy reduction can we achieve? Energy Consumption in Buildings

15 Gestão de Energia Slide 15 of 53 How much does it cost? Energy Consumption in Buildings

16 Gestão de Energia Slide 16 of 53 Buildings – High Performance Envelope The effectiveness of the thermal envelope depends on insulation levels in the walls, ceiling and basement –Insulation levels control the heat flow by conduction & convection through the exterior and the interior

17 Gestão de Energia Slide 17 of 53 Buildings – High Performance Envelope The effectiveness of the thermal envelope depends on insulation levels in the walls, ceiling and basement –Insulation levels control the heat flow by conduction & convection through the exterior and the interior

18 Gestão de Energia Slide 18 of 53 Buildings – High Performance Envelope The effectiveness of the thermal envelope depends on insulation levels in the walls, ceiling and basement –Insulation levels control the heat flow by conduction & convection through the exterior and the interior –U value (W/m 2 /K), the heat transfer coefficient, is equal to the heat flow per unit area and per degree of inside to outside temperature difference –The U value of a layer of insulation depends on its thickness l and type of material (conductivity – C)

19 Gestão de Energia Slide 19 of 53 Buildings – High Performance Envelope The effectiveness of the thermal envelope depends on insulation levels in the walls, ceiling and basement Foam insulation The most highly insulated houses have a heat transfer coefficient of U= W/m 2 /K Blown-in cellulose insulation (fills the gaps) Vaccum insulation panels Cork W/m/K

20 Gestão de Energia Slide 20 of 53 Evolution for the heat transfer coefficients in new buildings in Portugal

21 Gestão de Energia Slide 21 of 53 Buildings – High Performance Envelope The effectiveness of the thermal envelope depends on the insulation levels of windows –Windows offer substantially less resistance to the loss of heat than insulated walls –Single glazed windows have a typical U-value of 5W/m 2 /K which can be reduced to to 2.5 and 1.65W/m 2 /K with double and triple glazing because of the additional layers of air –The U-value of 2.5W/m 2 /K of double glazed windows can be reduced to 2.4W/m 2 /K and 2.3W/m 2 /K with Argon and krypton –Double and triple glazing vaccum windows can reduce the U value to 1.2 and 0.2W/m 2 /K

22 Gestão de Energia Slide 22 of 53 The effectiveness of the thermal envelope depends on the gain/loss energy by radiation –Windows permit solar energy to enter and loss of infrared radiation –The solar heat gain coefficient, SHGC, is the fraction of solar radiation inicident on a window that passes through the window –Low emissivity coatings reflect more (reduce SHGC), i.e., reduce heat gains in summer and winter –Low emissivity coatings can reduce loss of heat by infrared radiation Buildings – High Performance Envelope

23 Gestão de Energia Slide 23 of 53 Buildings – High Performance Envelope The effectiveness of the thermal envelope depends on the air leakage –The net heat flow due to an air exchange at rate r is:

24 Gestão de Energia Slide 24 of 53 Buildings – High Performance Envelope The effectiveness of the thermal envelope depends on the air leakage –The internal energy change due to an air exchange at rate r is: –The stack effect promotes air leakage Warm air is lighter Stack effect can account for up to 40% of heating requirements on cold climates –The wind effect

25 Gestão de Energia Slide 25 of 53 Buildings – High Performance Envelope The effectiveness of the thermal envelope depends on the air leakage –Careful application of a continuous air barrier can reduces rates of air leakage by a factor of 5 to 10 compared to standard practice (enforcement of careful workmanship during construction) –Buildings with very low air leakage require mechanical ventilation (95% of the available heat in the warm exhaust air can be transfered to the incoming cold air) to keep indoor air quality

26 Heat Exchangers: –Used in power plants, air conditioners, fridges, liquefication of natural gas, etc –Transfer energy between fluids at different temperatures Energy Balance in Open Systems Counter-flow Heat exchanger Direct Flow Heat Exchanger

27 Gestão de Energia Slide 27 of 53 Buildings – The role of shape, form, orientation and glazed % Building shape & form –Have significant impacts on heating and cooling loads and daylight because of the relation between surface area and volume –Which one minimizes heat transfer by conduction and convection?

28 Gestão de Energia Slide 28 of 53 Buildings – The role of shape, form, orientation and glazed % Building orientation –For rectangular buildings the optimal orientation is with the long axis facing south –Why?

29 Gestão de Energia Slide 29 of 53 Buildings – The role of shape, form, orientation and glazed % Glazing fractions –High glazing fractions increase energy requirements for heating and cooling –There is little additional daylighting benefit once the glazed fraction increases beyond 30-50% of the total façade area

30 Gestão de Energia Slide 30 of 53 Buildings – The role of shape, form, orientation and glazed % House size –The living area per family member increased by a factor of 3 between 1950 and 2000 in the US

31 Gestão de Energia Slide 31 of 53 Buildings –Passive (almost) solar heating, ventilation & cooling Evaporative Cooling:

32 Gestão de Energia Slide 32 of 53 Buildings –Passive (almost) solar heating, ventilation & cooling Evaporative Cooling:

33 Gestão de Energia Slide 33 of 53 Buildings – Passive (almost) solar heating, ventilation & cooling Thermal & wind induced ventilation & cooling: Earth Pipe cooling

34 Gestão de Energia Slide 34 of 53 Buildings – Passive (almost) solar heating, ventilation & cooling Thermal & wind induced ventilation & cooling: Large Atria

35 Gestão de Energia Slide 35 of 53 Buildings – Passive (almost) solar heating, ventilation & cooling Thermal & wind induced ventilation & cooling:

36 Gestão de Energia Slide 36 of 53 Buildings – Passive (almost) solar heating, ventilation & cooling Thermal & wind induced ventilation & cooling: Wind catcher

37 Gestão de Energia Slide 37 of 53 Buildings – Passive (almost) solar heating, ventilation & cooling Passive Solar Heating & Lighting Shading Light tubes

38 Gestão de Energia Slide 38 of 53 Buildings – Passive (almost) solar heating, ventilation & cooling Passive Solar Heating & Lighting Parede Trombe

39 Gestão de Energia Slide 39 of 53 Buildings: Mechanical Equipment In evaluating the energy efficiency of Mechanical Equipment the overall efficiency from primary to useful energy should be taken into account This is particularly important in the case of using Mechanical Equipments that use electricity (produced from fossil fuels)

40 Gestão de Energia Slide 40 of 53 Buildings: Mechanical Equipment for heating Furnaces –heat air and distribute the heated air through the house using ducts; –are electric, gas-fired (including propane or natural gas), or oil-fired. –Efficiencies range from 60 to 92% (highest for condensing furnaces) Boilers –heat water, and provide either hot water or steam for heating; –heat is produced from the combustion of such fuels as natural gas, fuel oil, coal or pellets. –Efficiencies range from 75% to 95% (highest for condensing boilers)

41 Gestão de Energia Slide 41 of 53 Buildings: Mechanical Equipment for heating & cooling Electrical-resistance heating –Overall efficiency can be quite low (primary -> useful) Heat-Pumps –Overall efficiency can be quite good –It decreases with T –Air-source and ground-source –For cooling & heating District Heating/Colling –For heating & cooling –Users dont need mechanical equipment

42 Gestão de Energia Slide 42 of 53 Buildings: Mechanical Equipment for cooling Chillers –Produce cold water which is circulated through the building –Electric Chillers: use electricity, COP = (larger units have a higher COP) –Absorption chillers: use heat (can be waste heat from cogeneration), COP =

43 Gestão de Energia Slide 43 of 53 Buildings: HVAC Systems Ventilate and heat or cool big buildings All air systems: air at a sufficient low (high) T and in sufficient volumes is circulated through the building to remove (add) heat loads –CAV: constant air volumes –VAV: variable air volumes –Air that is circulated in the supply ducts may be taken entirely from the outside and exhausted to the outside by the return ducts or a portion of the return air may be mixed with fresh air –Incoming air needs to be cooled and dehumidified in summer and heated and (sometimes) humidified in winter Restrict air flow to ventilation needs and use additional systems for additional heating/cooling Heat exchangers that transfer heat between outgoing and incoming air flows

44 Gestão de Energia Slide 44 of 53 Buildings: Mechanical Equipment for water heating Electrical and natural gas heaters –Efficiency of natural gas heaters is 76-85% –Efficiency of oil heaters is 75-83% –There is heat loss from storage tanks –Point-of-use tankless heaters have losses associated with the pilot light There are systems that recover heat from the warm wastewater with % efficiencies

45 Gestão de Energia Slide 45 of 53 European Directives European Directives on the Energy Performance of Buildings –Directive 2002/91/EC of the European Parliament and Council (on the energy performance of buildings): –http://ec.europa.eu/avservices/video/videoplayer.cfm?ref =I048425&videolang=en&sitelang=enhttp://ec.europa.eu/avservices/video/videoplayer.cfm?ref =I048425&videolang=en&sitelang=en –This was implemented by the Portuguese Legislation RCCTE and RCESE –Directive 2010/31/EU of the European Parliament and Council (on the energy performance of buildings) –This is implemented by the Portuguese Legislation DL 118/2013

46 Gestão de Energia Slide 46 of 53 Directive 2010/31/EU: Aims Reduction of energy consumption Use of energy from renewable sources Reduce greenhouse gas emissions Reduce energy dependence Promote security of energy supplies Promote technological developments Create opportunities for employment & regional development Links with aims of SGCIE?

47 Gestão de Energia Slide 47 of 53 Directive 2010/31/EU: Principles The establishment of a common methodology to compute Energy Performace –including thermal characteristics, heating and air conditioning instalations, renewable energies, passive heating and cooling, shading, natural light and design

48 Gestão de Energia Slide 48 of 53 Directive 2010/31/EU: Principles Set Minimum Energy Performance Requirements –Requirements should take into account climatic and local conditions and cost-effectiveness

49 Gestão de Energia Slide 49 of 53 Directive 2010/31/EU: Principles Energy Performance Requirements should be applied to new buildings & buildings going through major renovations

50 Gestão de Energia Slide 50 of 53 Directive 2010/31/EU: Principles Set System Requirements for: energy performance, appropriate dimensioning, control and adjustment for Technical Building Systems in existing and new buiildings

51 Gestão de Energia Slide 51 of 53 Directive 2010/31/EU: Principles Increase the number of nearly zero energy buildings

52 Gestão de Energia Slide 52 of 53 https://www.youtube.com/watch?v=pQFJr5E7_R0

53 Gestão de Energia Slide 53 of 53 Establish a system of Energy performace certificates. –Energy Performance certificates must be issued for constructed, sold or rented to new tenants –Buildings occupied by public authorities should set na example (ECO.AP in 300 public buildings in Portugal) Directive 2010/31/EU: Principles

54 Gestão de Energia Slide 54 of 53 Regular maintenance of air conditioning and heating systems Independent experts Directive 2010/31/EU: Principles

55 Gestão de Energia Slide 55 of 53 Implementation of the directives Directive 2002/91/EC was implemented with: Directive 2010/31/EU was implemented with: –DL 118/2013 (SCE, REH e RECS) 1.DL 78/2006, the National Energy Certification and Indoor Air Quality in Buildings (SCE). 2.DL 79/2006, Regulation of HVAC Systems of Buildings (RSECE). 3.DL 80/2006, Regulation of the Characteristics of Thermal Performance of Buildings (RCCTE).

56 Legislative Framework 1/17/ Despachos C/2013 Pre-certificates and Certificates templates D/2013 Conversion factors E/2013 Computation simplification rules F/2013 Climatic data G/2013 Testing and maintenance plan H/2013 Renewable energies I/2013 Energy demand calculation J/2013 Energy classification rules K/2013 Thermal parameters L/2013 Economic analysis methodology of energy efficiency measures Decreto-Lei n.º 118/2013 SCE – Buildings Energy Certificate System REH – Residential Buildings Energy Performance Regulation RECS – Commerce and Services Buildings Energy Performance Regulation Lei n.º 58/2013 Defines rules for SCE technicians Legislative framework is complemented by: 5 portarias 10 despachos Portarias 349-A/2013Role of SCE managing entity 349-B/2013 Methodology and requirements to classify residential buildings energy performance (REH) 349-C/2013 Permitting procedures and usage authorization of urban buildings 349-D/2013 Methodology and requirements to classify commerce and service buildings energy performance (RECS) 353-A/2013Indoor air quality DOCTORAL PROGRAM AND EXECUTIVE MASTER IN SUSTAINABLE ENERGY SYSTEMS ENERGY MANAGEMENT – 4TH GROUP WORK

57 Gestão de Energia Slide 57 of 53 Buildings that SCE applies to: –Edifícios ou fracções novos ou sujeitos a grande intervenção –Edifícios área útil > 1000m 2 ou > 500m 2 –Edifícios ou fracções a partir do momento da sua venda RCCTE – Domain of application SCE – Domain of Application

58 Gestão de Energia Slide 58 of 53 SCE – Fiscalização e Gestão Fiscalização e Gestão Obrigações Proprietários

59 Gestão de Energia Slide 59 of 53 SCE – Edifícios ZEB

60 Gestão de Energia Slide 60 of 53 REH Objectivos: –Requisitos mínimos para edifícios de habitação novos ou sujeitos a grandes alterações –Metodologia de caracterização do desempenho energético em condições nominais –Metodologia de desempenho dos sistemas técnicos

61 Gestão de Energia Slide 61 of 53 I3 (higher heating needs) and V3 (higher colling needs) RCCTE - Outdoor conditions Reference Outdoor conditions: Portugal is divided in winter and summer climatic zones Reference Indoor conditions 18ºC in heating season 25ºC in the cooling season Consumption of 40 liters of water at T+35ºC/occupant. day REH and RECS

62 Gestão de Energia Slide 62 of 53 RCCTE - Outdoor conditions Reference Winter Outdoor conditions: REH and RECS

63 Gestão de Energia Slide 63 of 53 Climate Heating Degree-days are: Where: Tb is the desired indoor temperature (18ºC) Tj is the temperature outside the hours j The Degree-days are calculated for an entire year For example, to Lisbon, for Tb = 18 º C, heating degree days are 1071 º C. day. Knowing the heating season is 5.3 months (160 days), the average daily GD (GDI) will be 6.7 º C. Heating Degree Days

64 Gestão de Energia Slide 64 of 53 Heating Degree Days – a comparison

65 Gestão de Energia Slide 65 of 53 RCCTE - Outdoor conditions Reference Summer Outdoor conditions: REH and RECS

66 Gestão de Energia Slide 66 of 53 Heat transfer coefficient: Factores solares RCCTE – Indices e parameters U Heat transfer coefficients of walls U max The corresponding maximum permissible Fs Solar factor of fenestration (for windows not facing NE-NW with area > 5%) Fs max The corresponding maximum permissible REH – Minimum requirements more demanding for harsher winters more demanding for harsher summers

67 Gestão de Energia Slide 67 of 53 Annual useful energy needs for cooling and heating in new buildings: Annual total primary energy in new buildings: RCCTE – Indices e parameters Nic Nominal Annual Needs of Useful Energy for Heating NiNiThe corresponding maximum permissible Nic Ni Nvc Nominal Annual Needs of Useful Energy for Cooling NvNvThe corresponding maximum permissible Nvc Nv REH – Thermal Behaviour

68 Gestão de Energia Slide 68 of 53 Heating Heating: Maximum Useful Nominal Needs (Ni) [kWh / (m 2.year)] Heating: Useful Nominal Needs (Nic) [kWh / (m 2.year)] Nic < Ni REH - Heating

69 Gestão de Energia Slide 69 of 53 Heating Heating: Maximum Useful Nominal Needs (Ni) [kWh / (m 2.year)] Heating: Useful Nominal Needs (Nic) [kWh / (m 2.year)] Nic = (Qtr,i + Qve,i – Qgu,i) / Ap Qt = x GD x (A x U) Qv = 0,024 (0,34 x R x Ap x Pd) x GD Qt: heat loss by conduction & convection through the surrounding Qv: heat losses resulting from air exchange Qgu: solar gain and internal load Nic < Ni REH - Heating Corrected if there is heat recovery

70 Gestão de Energia Slide 70 of 53 Current average residential heating energy use (Harvey, 2010) kWh/m 2 /yr for new residential buildings in Switzerland and Germany 220 kWh/m 2 /yr average of existing buildings in Germany kWh/m 2 /yr for existing buildings in central and eastern Europe Passive house standard: 15 kWh/m 2 /yr

71 Gestão de Energia Slide 71 of 53 Cooling Cooling: Maximum Useful Nominal Needs (Nv) [kWh/(m 2.year)] Cooling: Useful Nominal Needs (Nvc) [kWh / (m 2.year)] Nvc = Qg * (1 - ) / Ap (kWh/m 2 year) Qg : Total gross load (internal + walls + solar + air renewal) : Load Factor Nvc < Nv REH: Cooling

72 Gestão de Energia Slide 72 of 53 Cooling TPE: Maximum Nominal Needs (Nt) [kgep/(m 2.year)] TPE: Nominal Needs (Nvc) (Ntc) [kgep/(m 2.year)] REH: Total Primary Energy Ntc < Nt

73 Gestão de Energia Slide 73 of 53 REH: Conversion to Primary Energy Comparação com SGCIE - 1MWh needs toe?

74 Gestão de Energia Slide 74 of 53 REH – Equipment Energy Efficieny Os equipamentos de aquecimento e arrefecimento ambiente e de aquecimento de águas devem cumprir requisitos de eficiência A instalação de equipamento solar térmico para AQS (ou de outras renováveis) é obrigatória desde que a exposição solar seja adequada

75 Gestão de Energia Slide 75 of 53 Valor mínimo de renovação de ar de 0.4 por hora RCCTE – Indices e parameters REH – Thermal Behaviour

76 Gestão de Energia Slide 76 of 53 Energy label A A + B - B C D E F G New buildings R R = N tc / N t Energy Performance Certificate Energy Labelling:

77 Gestão de Energia Slide 77 of 53 https://meocloud.pt/link/34d bb-467b- 915e-78588c145383/Novo_CE_720p.mp4/https://meocloud.pt/link/34d bb-467b- 915e-78588c145383/Novo_CE_720p.mp4/


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