Energy Management: 2013/2014 Energy in Buildings Prof. Tânia Sousa [email protected].

Energy Management: 2013/2014

Energy in Buildings

Prof. Tânia [email protected]

mailto:[email protected]

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

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


1MWh=3.6GJ

16.45GJ

66.96GJ

34.70GJ

Gestão de Energia

Slide 4 of 53


• Final Energy use in buildings by fuel in 2007 in EJ

– Differences?

Residential Commercial &Public

Gestão de Energia

Slide 5 of 53


• 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

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 21.34 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)


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 21.34 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


Gestão de Energia

Slide 8 of 53


• 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

Gestão de Energia

Slide 9 of 53





– Meet the reduced load as much as possible using passive solar heating, ventilation and cooling techniques while optimizing the use of daylight

Gestão de Energia

Slide 10 of 53





– 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

Gestão de Energia

Slide 11 of 53

• How much energy reduction can we achieve?– Passive house standard:

heating 15kWh/m2 per yearcooling 15 kWh/m2 per yearTPE 120 kWh/m2 per yearn50 ≤ 0.6 / hour


Gestão de Energia

Slide 12 of 53

• How much energy reduction can we achieve?


Triple-glazed windows with internal venetian blinds & mechanical ventilation with 82% heat recovery

Gestão de Energia

Slide 13 of 53

Heating needs decreased from 220 kWh/m2/year to 30 kWh/m2/year



Triple-glazed windows with internal venetian blinds & mechanical ventilation with 82% heat recovery

Gestão de Energia

Slide 14 of 53



Gestão de Energia

Slide 15 of 53

• How much does it cost?


0

50

100

150

200

250

300

350

199

0

19

91

19

92

199

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199

4

199

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19

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8

199

9

20

00

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01

200

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3

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04

20

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7

20

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20

09

20

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Add

ition

alIn

vest

men

t(€/

m2 )

ofP

assi

veR

owH

ouse

s 1991 Prototype: experimental house,4 dwellings in Kranichstein usinghandicraft batch production

PH in Groß-Umstadt:Reduced costs bysimplification

Settlement in Wiesbaden:Serially produced windows & structural elements

Settlements in Wuppertal,Stuttgart, Hanover

Row houses in Darmstadt, 80 €/m2

Profitability with contemporary

interest rates & energy prices

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

Gestão de Energia

Slide 17 of 53





Q U T Area

Gestão de Energia

Slide 18 of 53





– U value (W/m2/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)

Q U T Area

U C l

Gestão de Energia

Slide 19 of 53



Foam insulation

The most highly insulated houses have a heat transfer coefficient of U=0.1-0.2 W/m2/K

Blown-in cellulose insulation (fills the gaps)

Vaccum insulation panels

Q U T Area U C l

Cork 0.06-0.07 W/m/K

Gestão de Energia

Slide 20 of 53

• Evolution for the heat transfer coefficients in new buildings in Portugal

Gestão de Energia

Slide 21 of 53


• 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/m2/K

which can be reduced to to 2.5 and 1.65W/m2/K with double

and triple glazing because of the additional layers of air

– The U-value of 2.5W/m2/K of double glazed windows can be

reduced to 2.4W/m2/K and 2.3W/m2/K with Argon and krypton

– Double and triple glazing vaccum windows can reduce the U

value to 1.2 and 0.2W/m2/K

Q U T Area U C l

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


Gestão de Energia

Slide 23 of 53


• The effectiveness of the thermal envelope depends on the air leakage– The net heat flow due to an air exchange at rate r is:

Gestão de Energia

Slide 24 of 53


• 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

p,airU V c Tair air

Gestão de Energia

Slide 25 of 53


• 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

• 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

22

, ,2 2ji

in i i i out j j ji j

vvdEQ W m h gz m h gz

dt

Counter-flow Heat exchanger

Direct Flow Heat Exchanger

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?

Gestão de Energia

Slide 28 of 53


• Building orientation– For rectangular buildings the optimal

orientation is with the long axis facing south

– Why?

Gestão de Energia

Slide 29 of 53


• 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

0

20

40

60

80

100

120

140

160

180

200

30% Base 60% Base 60% Upgraded

100% Base 100% Upgraded

En

erg

y In

ten

sity

(kW

h/m

2/y

r)

Heating Cooling LightingEquipment Pumps & fans Server rooms

Gestão de Energia

Slide 30 of 53


• House size– The living area per family member increased by a factor of 3

between 1950 and 2000 in the US

Gestão de Energia

Slide 31 of 53

Buildings –Passive (almost) solar heating, ventilation & cooling

• Evaporative Cooling:

Gestão de Energia

Slide 32 of 53

Buildings –Passive (almost) solar heating, ventilation & cooling

• Evaporative Cooling:

Gestão de Energia

Slide 33 of 53

Buildings – Passive (almost) solar heating, ventilation & cooling

• Thermal & wind induced ventilation & cooling:

Earth Pipe cooling

Gestão de Energia

Slide 34 of 53



Large Atria

Gestão de Energia

Slide 35 of 53



Gestão de Energia

Slide 36 of 53



Wind catcher

Gestão de Energia

Slide 37 of 53


• Passive Solar Heating & Lighting

Shading

Light tubes

Gestão de Energia

Slide 38 of 53


• Passive Solar Heating & Lighting

Parede Trombe

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)

final

primary

E

E

useful

final

E

E

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)

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 don’t need

mechanical equipment

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 = 4.0-7.5 (larger

units have a higher COP)– Absorption chillers: use heat (can be waste heat from

cogeneration) , COP = 0.6-1.2

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

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 45-65 % efficiencies

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=I

048425&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

http://ec.europa.eu/avservices/video/videoplayer.cfm?ref=I048425&videolang=en&sitelang=en

http://ec.europa.eu/avservices/video/videoplayer.cfm?ref=I048425&videolang=en&sitelang=en

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?

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

Gestão de Energia

Slide 48 of 53


• Set Minimum Energy Performance Requirements– Requirements should take into account climatic and local

conditions and cost-effectiveness

Gestão de Energia

Slide 49 of 53


• Energy Performance Requirements should be applied to new buildings & buildings going through major renovations

Gestão de Energia

Slide 50 of 53


• Set System Requirements for: energy performance, appropriate dimensioning, control and adjustment for Technical Building Systems in existing and new buiildings

Gestão de Energia

Slide 51 of 53


• Increase the number of nearly zero energy buildings

Gestão de Energia

Slide 52 of 53

• https://www.youtube.com/watch?v=pQFJr5E7_R0

https://www.youtube.com/watch?v=pQFJr5E7_R0

https://www.youtube.com/watch?v=pQFJr5E7_R0

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)


Gestão de Energia

Slide 54 of 53

• Regular maintenance of air conditioning and heating systems

• Independent experts


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).

DOCTORAL PROGRAM AND EXECUTIVE MASTER IN SUSTAINABLE ENERGY SYSTEMS ENERGY MANAGEMENT – 4TH GROUP WORK

56

Legislative Framework

1/17/2014

Despachos15793-C/2013 Pre-certificates and Certificates templates

15793-D/2013 Conversion factors

15793-E/2013 Computation simplification rules

15793-F/2013 Climatic data

15793-G/2013 Testing and maintenance plan

15793-H/2013 Renewable energies

15793-I/2013 Energy demand calculation

15793-J/2013 Energy classification rules

15793-K/2013 Thermal parameters

15793-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 RegulationRECS – Commerce and Services Buildings Energy Performance Regulation

Lei n.º 58/2013Defines rules for SCE technicians

Legislative framework is complemented by:

5 portarias10 despachos

Portarias349-A/2013 Role 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/2013Methodology and requirements to classify commerce and service buildings’ energy performance (RECS)

353-A/2013 Indoor air quality

http://www.mitportugal.org/

Gestão de Energia

Slide 57 of 53

• Buildings that SCE applies to:– Edifícios ou fracções novos ou sujeitos a grande

intervenção

– Edifícios área útil > 1000m2 ou > 500m2

– Edifícios ou fracções a partir do momento da sua venda

RCCTE – Domain of applicationSCE – Domain of Application

Gestão de Energia

Slide 58 of 53

SCE – Fiscalização e Gestão

• Fiscalização e Gestão

• Obrigações Proprietários

Gestão de Energia

Slide 59 of 53

SCE – Edifícios ZEB

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

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

Gestão de Energia

Slide 62 of 53


Reference Winter Outdoor conditions:

REH and RECS

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.

24

se;1i

days Heating

1iiannual 24

where jb TTj

jb TTGDGDGD

Heating Degree Days

Gestão de Energia

Slide 64 of 53

Heating Degree Days – a comparison

0

1000

2000

3000

4000

5000

6000

Edmonto

n

Win

nipeg

Toronto

Vanco

uver

Berlin

Vienna

Helsi

nki

He

ati

ng

De

gre

e D

ay

s (

K-d

ay

s)

Gestão de Energia

Slide 65 of 53


Reference Summer Outdoor conditions:

REH and RECS

Gestão de Energia

Slide 66 of 53

• Heat transfer coefficient:

• Factores solares

RCCTE – Indices e parameters

U Heat transfer coefficients of walls

Umax The corresponding maximum permissible

Fs Solar factor of fenestration (for windows not facing NE-NW with area > 5%)

Fsma

x

The corresponding maximum permissible

REH – Minimum requirements

more demanding for harsher winters

more demanding for harsher summers

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

Ni The corresponding maximum permissibleNic ≤ Ni

Nvc Nominal Annual Needs of Useful Energy for Cooling

Nv The corresponding maximum permissibleNvc ≤

Nv

REH – Thermal Behaviour

Gestão de Energia

Slide 68 of 53

Heating

Heating: Maximum Useful Nominal Needs (Ni) [kWh / (m2.year)]

Heating: Useful Nominal Needs (Nic) [kWh / (m2.year)]

Nic < Ni

REH - Heating

Gestão de Energia

Slide 69 of 53

Heating

Heating: Maximum Useful Nominal Needs (Ni) [kWh / (m2.year)]

Heating: Useful Nominal Needs (Nic) [kWh / (m2.year)]

Nic = (Qtr,i + Qve,i – Qgu,i) / Ap

Qt = 0.024 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

Gestão de Energia

Slide 70 of 53

Current average residential heating energy use (Harvey, 2010)

• 60-100 kWh/m2/yr for new residential buildings in Switzerland and Germany

• 220 kWh/m2/yr average of existing buildings in Germany

• 250-400 kWh/m2/yr for existing buildings in central and eastern Europe

• Passive house standard: 15 kWh/m2/yr

Gestão de Energia

Slide 71 of 53

Cooling

Cooling: Maximum Useful Nominal Needs (Nv) [kWh/(m2.year)]

Cooling: Useful Nominal Needs (Nvc) [kWh / (m2.year)]

Nvc = Qg * (1 - ) / Ap (kWh/m2year)

Qg : Total gross load (internal + walls + solar + air renewal)

: Load Factor

Nvc < Nv

REH: Cooling

Gestão de Energia

Slide 72 of 53

Cooling

TPE: Maximum Nominal Needs (Nt) [kgep/(m2.year)]

TPE: Nominal Needs (Nvc) (Ntc) [kgep/(m2.year)]

REH: Total Primary Energy

Ntc < Nt

Gestão de Energia

Slide 73 of 53

REH: Conversion to Primary Energy

Comparação com SGCIE - 1MWh needs 0.217 toe?

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

Gestão de Energia

Slide 75 of 53

• Valor mínimo de renovação de ar de 0.4 por hora

RCCTE – Indices e parametersREH – Thermal Behaviour

Gestão de Energia

Slide 76 of 53

Energy label

A A+

B- B

C

D

E

F

G

New buildings

1

2

3

R

R = Ntc / Nt

Energy Performance Certificate

• Energy Labelling:

Gestão de Energia

Slide 77 of 53

• https://meocloud.pt/link/34d44317-19bb-467b-915e-78588c145383/Novo_CE_720p.mp4/

https://meocloud.pt/link/34d44317-19bb-467b-915e-78588c145383/Novo_CE_720p.mp4/



Energy Management: 2013/2014 Energy in Buildings Prof. Tânia Sousa [email protected].

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Transcript of Energy Management: 2013/2014 Energy in Buildings Prof. Tânia Sousa [email protected].