Revision of REHVA nZEB technical definition for nearly ... › fileadmin › events › eventspdf › REHVA_Semin… · Federation of European Heating, Ventilation and Air-conditioning

Federation of European Heating, Ventilation and Air-conditioning Associations

Revision of REHVA nZEB

technical definition for nearly

zero energy buildings

Jarek Kurnitski Professor, Vice-president REHVA

Tallinn University of Technology

[email protected]

REHVA Technical Seminar, Buildings and HVAC-Products

Related EU Regulations, October 18, 2012 Brussels

mailto:[email protected]


Background

• EPBD recast (2010/31/EU) launched nZEB target in 2010 with the need

for the Member States to define what nZEB for them exactly constitutes

• REHVA realized the problem that various definition of nZEB may cause

in Europe

• CEN EPBD standards published 2007/2008 do not include nZEB and

have system boundary definitions with national decision options – which

depending on the choice, may lead to conflict with EPBD recast for on-

site renewable energy utilization

• In this situation, REHVA nZEB definition/energy calculation system

boundaries launched in May 2011 were widely utilized and affected the

preparation of national definitions, codes and calculation methods in

many countries as only available methodology

• REHVA definition has been popular: at the time the revision was decided

in 4/2012 it was viewed 1070 times and was downloaded 409 times


Simplified system boundary with major

energy flows – illustrative changes

For thermal and electrical energy it applies: Delivered – exported energy = energy use – on site renewable

net

i

iiidel

A

fEE

E

exp,,

net

i

ii

i

idelidel

A

fEfE

E

exp,exp,,,

Total energy useof the building

Delivered energy

Exported energy

Building site = system boundary of delivered and exported energy

System boundary of building technical systems

(simplified primary

energy equation is

deleted)


EPBD recast – Nearly zero energy

buildings nZEB

• In the directive ‘nearly zero-energy building’ means a building that has a very high energy performance. The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby.

nZEB = very high energy performance + on-site renewables

• Definition of “a very high energy performance“ and “significant extent of renewables” let for Member States


Most difficult decisions in the

preparation of REHVA definition in 2011

• On site renewable energy is inside the system boundary, i.e. is

directly subtracted from energy use (is not treated as delivered

energy – the option of EN 15603:2008)

– This is confirmed in the EC’s Cost-optimal regulations (No 244/2012).

Quote: “the RES-based active technologies enter into direct

competition with demand-side solutions, which is in line with the

purpose and intention of the cost optimal calculation to identify the

solution that represents the least global costs without discriminating

against or favouring a certain technology.”

• Primary energy factors are by the definition of the system

boundary non-renewable primary energy factors

– EC’s Cost-optimal regulations requires the use of non-renewable

primary energy in the cost optimality assessment

– (in reality, factors for renewable fuels often in between of the total and

non-renewable, and energy policy has an effect)


Detailed system boundary – illustrative changes

BUILDING

NEEDSHeatingCooling

VentilationDHW

LightingAppliances

Building site boundary = system boundary of delivered and exported energy

Heating energy

Cooling energy

Electricity for

lighting

Fuels

ENERGY

USE

BUILDING

TECHNICAL SYSTEMS

Energy use and production

System losses

and conversions

Electricity

ON SITE RENEWABLE

ENERGY W/O FUELS

District heat

District cooling

Electricity

Solar gains/

loads

Heat

transmission

ENERGY NEED

DELIVERED

ENERGY

EXPORTED

ENERGY

(renewable and

non-renewable)

Electricity for

appliances

Internal heat

gains/loads

RE generators

He

atin

g e

n.

Ele

ctr

icity

Co

olin

g e

n.

Energy use SB

Cooling en.

Heating en.Energy need SB

• System boundaries (SB) for energy need, energy use and delivered and exported energy calculation. The last one may be interpreted as the building site boundary.

• Demand reduction measures can be distinguished from RE solutions in the energy use SB, not in the delivered/exported energy SB


Reasons for the revision

• EC’s Cost-optimal regulation (EU No 244/2012), January 2012, confirmed

the principles used in Rehva delivered/exported/primary energy

calculation frame, but RES (renewable energy contribution) calculation

was not included in the REHVA definition/system boundary

• RES was strongly needed, because it can be easily mixed with

delivered/exported energy calculation

• EPBD standards will be revised – coordination with CEN project-team –

as only available methodology with calculation examples REHVA

document is also important input to CEN

• Many countries work with national definitions – the cost optimal regulation

provided extra reporting time by March 2013

• Cost optimal calculations include nZEB performance levels – detailed

technical definitions needed

• The EPBD laws and regulations shall be adopted and published in MS by

9 July 2012 and most of requirements shall apply from 9 January 2013,

but preparation of fully nZEB compliant regulation is longer process


Some major revisions of the Draft

v3 (Sept 05, 2012) • RER – renewable energy ratio equation included

• time step issue (to be able to calculate exported energy)

addressed in page 9

• additional CO2 indicator added, Eq. 4

• ≤ 0 added to ZEB definition with explanation of “net” and

reference to Sartori, page 11

• improved wording for nZEB definition, page 11

• explanation of renewable energy nearby, page 17

• sites with multiple buildings, Figure 5

• explanation of heat pump equations, Figure 7

• new chapter on load matching and grid interactions, Ch. 4.4

• comments on emission/distribution losses in examples, Ch. 5


REHVA nZEB definition (improved wording, no major changes)

net zero energy building (ZEB) Energy use of ≤ 0 kWh/(m2 a) primary energy.

NOTE A net ZEB is typically a grid connected building with very high energy performance. A net ZEB balances its

primary energy use so that the primary energy feed-in to the grid or other energy network equals to the primary energy

delivered to ZEB from energy networks. Annual balance of 0 kWh/(m2 a) primary energy use typically leads to the

situation where significant amount of the on-site energy generation will be exchanged with the grid.

nearly zero energy building (nZEB) Technically and reasonably achievable national energy use of > 0 kWh/(m2 a)

primary energy, achieved with a combination of best practice energy efficiency

measures and renewable energy technologies which may or may not be cost

optimal.

NOTE 1 ‘reasonably achievable’ means by comparison with national energy use benchmarks appropriate to the

activities served by the building, or any other metric that is deemed appropriate by each EU Member State.

NOTE 2. Renewable energy technologies needed in nearly zero energy buildings may or may not be cost-effective,

depending on available national financial incentives.

ZEB has exact performance

level of ≤ 0 kWh/(m2 a)

primary energy use

nZEB depends on national

conditions


Example of nZEB office – primary energy

• Electricity use of cooling, ventilation, lighting and appliances is 39.8 kWh/(m2 a)

• Solar electricity of 15.0 kWh/(m2 a) reduces the net delivered electricity to 24.8 kWh/(m2 a)

• Net delivered fuel energy (caloric value) is 4.2 kWh/(m2 a) and primary energy is 66 kWh/(m2 a)

3.8 heating

11.9 cooling

10.0 lighting

BUILDING TECHNICAL SYSTEMS

15.0 PV electricity,from which 6.0 used in the building and 9.0 exported

Fuel 4.2

Electricity 33.8

Solar and internal heat gains/loads

Heat exchange through the building envelope

NET ENERGY NEED (47.2 kWh/(m2 a))

DELIVERED ENERGYBoiler3.8/0.9 = 4.2

Free cooling 4.0/10 = 0.4 Compressor cooling 7.9/3.5 = 2.3

Lighting 10.0

Ventilation 5.6

Appliances 21.5

Primary energy: 4.2*1.0 + (33.8-9.0)*2.5 = 66 kWh/(m2 a)

EXPORTED ENERGY

System boundary of net delivered energy

Ne

t de

live

red

en

erg

y

Electricity 9.0

21.5 appliances

(Sum of electricity 39.8)

21,5

10

3,2

0,61,1

10,8

NET ENERGY NEED (47.2 kWh/(m2 a))

Appliances (users')Lighting

Space

heatingHeating of air in AHUCooling in room unitsCooling of air in AHU


New: RER system boundary

Heating energy

Cooling energy

Fuels

RENEWABLE

ENERGY USE

BUILDING

TECHNICAL SYSTEMS

Energy use and production

System losses

and conversions

Electricity

ON SITE RE SOURCES

District heat

District cooling

Electricity

DELIVERED ENERGY (renewable and non-renewable)

EXPORTED ENERGY (renewable and non-renewable)

RE generators

(solar, wind, hydro)

He

atin

g e

n.

Ele

ctr

icity

Co

olin

g e

n.

RE energy use SB

Cooling en.

Heating en.

RE generators

(geo- , aero- and hydrothermal)

ON SITE RE SOURCES

New element

in the system

boundary

• Thermal energy from ambient heat exchangers to be accounted (in the

delivered/exported energy calculation calculated with COP)


New: RER Equation (not weighted energy)

expexp

exp

NRECNRECRECRECREC

RECRECRECRER

siteoffsiteon

siteoffsiteon

where

RER is the renewable energy ratio, -; RECon-site is the collection of the renewable energy carriers produced on-site, kWh/a; RECexp is the collection of the renewable energy carriers produced on-site and exported, kWh/a; RECoff-site is the collection of the delivered (imported) renewable energy carriers produced off-site, kWh/a; NREC is the collection of the delivered (imported) non-renewable energy carriers, kWh/a; NRECexp is the collection of the exported non-renewable energy carriers, kWh/a.


RER example: Figure 9 in the working document

• Discussion on the RECexp term, 9.0 in the figure – should or

should not subtracted? (Not subtracted in the CEN proposal)

4.0 aerothermal

BUILDING TECHNICAL SYSTEMS

15.0 PV electricity,from which 6.0 is used in the

building and 9.0 exported

Fuel 4.2

Electricity 33.8

(20% renewable)

SOLAR ENERGY

DELIVERED ENERGYBoiler3.8/0.9 = 4.2

Free cooling 4.0/10 = 0.4 Compressor cooling 7.9/3.5 = 2.3

Lighting 10.0

Ventilation 5.6

Appliances 21.5 EXPORTED ENERGY

Electricity 9.0

(Sum of electricity 39.8)

Solar panels

System boundary of renewable energy

Condenser(air cooled liquid chiller)

AEROTHERMAL ENERGY

Renewable energy ratio:

35,08.338.02.48.332.00.90.40.15

8.332.00.90.40.15

RER


New: system boundary for multiple buildings

Building site boundary = system boundary of delivered and exported energy

Fuels

Electricity

District heat

District cooling

Electricity

DELIVERED

ENERGY

EXPORTED

ENERGY

(renewable and

non-renewable)

Building 1

Cooling en.

Heating en.

Building 2

Building n

SITE ENERGY

CENTRE


Coordination with CEN

• CEN has started the preparation of 2nd generation of CEN-

EPBD standards (CEN mandate M/480)

• CEN comments prepared by CTL collective team leaders group

working in parallel on the same subjects

• 2-way information exchange – REHVA document utilized in the

preparation of EPBD Overarching Standard

• CEN has utilized and further developed the RER – assessment

boundary for renewable energy contribution calculation

• In the CEN proposal, primary energy factors are included in the

RER equation (REHVA draft v3 operates with not weighted

energy flows)

• CEN also provided improved wording for clear distinction

between on-site, nearby and off-site, as well as the use of CEN

symbols and some other specific comments


Next steps

• Final draft v4 will be prepared for REHVA TF approval

procedure

• Final draft will be available in December 2012 – roughly the

same schedule as for CEN EPBD Overarching Standard

• Will include the summary of available nZEB and low energy

definitions in MS

• To be published in February 2013


nZEB case studies • nZEB office buildings in France, Netherlands, Switzerland and Finland

reported according to REHVA definition (and can be compared), see REHVA Journal (3/2011 and 2/2012)


• Is intended to help the experts in the Member States in defining the

nearly zero energy buildings in a uniform way – so that local

conditions are taken into account, but the uniform methodology used

• Can be seen as a proposal for uniformed national implementation of

EPBD

• Proposes a technical definition for nZEB buildings following EPBD

recast and Cost-optimal regulation

• Provides energy calculation framework and system boundaries

associated with the definition to specify which energy flows in which

way are taken into account

The original objective of REHVA nZEB

definition does not need revision

Documents

Revision of REHVA nZEB technical definition for nearly ... › fileadmin › events › eventspdf › REHVA_Semin… · Federation of European Heating, Ventilation and Air-conditioning