The EN 15603 standasrd proposes a definition of the energy use of a building for its use (heating, cooling, ventilation, lighting and other appliances) and methods for measuring or calculating this quantity. It leaves however some freedom to the user (such as an EU member state). Before defining what an NZEB (or ZEB) is, several political decisions should be taken:

1) What is the time step for the evaluation of the energy use: an hour (in which case the peak power is limited for an NZEB or a ZEB should be fully autonomous) or, at the other limit, several years, in which case the energy use is limited and a ZEB could store its excess production in the grid for a later use.

2) Energy is needed for anything. Which one is taken into account? Only the energy for using the building (heating, cooling, ventilation, lighting and other appliances) or also the energy necessary for construction, maintenance, demolition and recycling (grey energy)? Should we in adddition take into account the energy embedded in the materials and services used by the occupants (food, clothes, papers, internet, etc.) or the energy they use for transportation?

What are the boundaries of the building for the evalutation of its energy use and production? Should we include only the energy produced on the building, or could we include energy produced on site but not on the building, or by the building owner on another site?

3) and, of course, how much is "near zero"?

In Switzerland, we use EN 15603 on a treee-year average, without including the grey energy, and two types of weighting are used before summing up the various energywares: The Swiss Society of Architects and Engineers propose the use of primary energy factors to get the total primary energy use of the buildings, while the states propose the use of political factors (0,7 for wood, 1 for fossile agents and 2 for electricity). The boundaries of the building is the building itself. Production on site is included if it delivers energy to the building first.

We don't have a definition for "near zero". However, buildigns constructed now according to regulations use 4 times less energy than those built according to past century standards. The definition commmonly used for zero energy buildings is "net zero primary energy use of the building on an annual basis for heating, cooling, ventilation, lighting and other appliances", the grey energy being not taken into account. The renewable energy produced and used on site (e.g. passive and active solar energy) is also not taken into account, but of course decreases the amount of purchaded energy use.

Dear Claude,

That is a good answer. Thank you!

The main question is of course how near to “Zero Energy Building” is this “near Zero Energy Building”.

In my Conference Paper “Solar architecture and Zero energy house “(in 2009 year) I propose how to obtain the “zero line” which location is near to “low energy building” (nearly 40-50 kWh/m2a) Now I take part in preparing of Bulgarian nZEB`s definition.

I know about MINERGY - Swiss building standard for lower energy consumption at a higher level of comfort.

You say “ the buildigns constructed now according to regulations use 4 times less energy than those built according to past century standards”.

How does MINERGY take part in Swiss regulations today?

Regards

Savov

Minergy is a private company partly owned by swiss states (cantons). Therefore, Minergy has some influence on the regulations. The official regulations only limit the heating requirements to about 15 kWh/m² gross heated floor area (the limit depends on building type and local climate), while the Minergy basic standard limits the energy for heating, cooling, ventilation and hot water to 38 kWh/m². There are no official regulations about other needs, but the Swiss Society of Architects and Engineers, which drafts all building standards, proposes a reference value at about 140 kWh/m² primary energy for all building needs. Once again, the limit depends on the building type. This reference values is used for the building energy certificate according to EN 15217, and corresponds to the top of class B. Class A buildings ¨(that are not considered as NearZEBs) should not use more than half of this.

Dear Claude-Alain,

Thank you for your answer.

In our upcoming regulation class A will be given only for nZEB (there are 10 types of buildings) For example for residential buildings the energy for heating, cooling, ventilation, domestic hot water and lighting will be limit between to 48–95 kWh/m2a. In addition we should take into account requirement that 55% of primary energy should be RES and obtained on site near to the buildings etc.

Our country is divided on nine climatic zones.

How many climatic zones there are in Switzerland?

How do they influence on building regulations?

If you build one and same house class A in different zones will there different reference values for U (W/m2K) for elements of building skins as walls, windows etc. etc...

Regards

Savov

Dear Savov

Climatic zones depend on the climatic date we look at. For the general meteorological conditiosn, we have the Jura mountains, the Swiss Plateau from Geneva to Konstanz, the Alps and south of the Alps.

For building regulations however, we look only at the outdoor temperature in winter, and the limit for the heating requirements depends on the altitude only.

Today's method for buildign energy labelling (wich defines also what an "A" building is) has a fixed limit for the total annual primary energy use, that does not depend on climate, but on building use only. for example, totday's limit for an "A" muiltifamilyhouse is 80 kWh/m² floor area. This is however not considered as a "Near zero energy building", but a good one, using half of the Swiss standard.

We do not have, basically, requirement on U-values. It is up to the designer to install enough thermal insulation to reduce the heating energy use below the limit.

I should however inform you that the method for building energy labelling is now under revision, and the limits may depend on the climate and building shape in the future.

Best regards

Claude-Al.

Dear Claude-Alain

Thank you for your detailed explication

I look forward to the changes in your method for building energy labelling

I am tempted to ask you about the French Effiergie what is a difference between the French Effinergie , the Suisse Minergy and German Passivhaus

Best regards

Savov

Dear Savov

I looked for information on the web and have summarised it on the attached file,

Best regards

Claude-Al.

Dear Claude-Alain,

Thank you for your answer.

Best regards

Savov

To investment in "Nearly Zero Energy Buildings" is firstly question of obtain optimum betwen the high energy efficiency of the building and the cost spending in realization in this investment.

http://www.cibseireland.org/wp-content/uploads/2013/04/2013-03-20-CIBSE-Part-L-J.pdf

Zero net site energy use

In this type of ZNE, the amount of energy provided by on-site renewable energy sources is equal to the amount of energy used by the building. In the United States, “zero net energy building” generally refers to this type of building.

Zero net source energy use

This ZNE generates the same amount of energy as is used, including the energy used to transport the energy to the building. This type accounts for losses during electricity transmission. These ZNEs must generate more electricity than zero net site energy buildings.

Net zero energy emissions

Outside the United States and Canada, a ZEB is generally defined as one with zero net energy emissions, also known as a zero carbon building or zero emissions building. Under this definition the carbon emissions generated from on-site or off-site fossil fuel use are balanced by the amount of on-site renewable energy production. Other definitions include not only the carbon emissions generated by the building in use, but also those generated in the construction of the building and the embodied energy of the structure. Others debate whether the carbon emissions of commuting to and from the building should also be included in the calculation.

Net zero cost

In this type of building, the cost of purchasing energy is balanced by income from sales of electricity to the grid of electricity generated on-site. Such a status depends on how a utility credits net electricity generation and the utility rate structure the building uses.

Net off-site zero energy use

A building may be considered a ZEB if 100% of the energy it purchases comes from renewable energy sources, even if the energy is generated off the site.

Off-the-grid

Off-the-grid buildings are stand-alone ZEBs that are not connected to an off-site energy utility facility. They require distributed renewable energy generation and energy storage capability (for when the sun is not shining, wind is not blowing, etc.). An energy autarkic house is a building concept where the balance of the own energy consumption and production can be made on an hourly or even smaller basis. Energy autarkic houses can be taken off-the-grid.

Net zero-energy building

Based on scientific analysis within the joint research program “Towards Net Zero Energy Solar Buildings” [4] a methodological framework was set up which allows different definitions, in accordance with country’s political targets, specific (climate) conditions and respectively formulated requirements for indoor conditions: The overall conceptual understanding of a Net ZEB is an energy efficient, grid connected building enabled to generate energy from renewable sources to compensate its own energy demand 

The wording “Net” emphasizes the energy exchange between the building and the energy infrastructure. By the building-grid interaction, the Net ZEBs becomes an active part of the renewable energy infrastructure. This connection to energy grids prevents seasonal energy storage and oversized on-site systems for energy generation from renewable sources like in energy autonomous buildings. The similarity of both concepts is a pathway of two actions: 1) reduce energy demand by means of energy efficiency measures and passive energy use; 2) generate energy from renewable sources. However, the Net ZEBs grid interaction and plans to widely increase their numbers [5] evoke considerations on increased flexibility in the shift of energy loads and reduced peak demands.[6]

Within this balance procedure several aspects and explicit choices have to be determined:

The building system boundary is split into a physical boundary which determines which renewable resources are considered (e.g. in buildings footprint, on-site or even off-site, see [7]) respectively how many buildings are included in the balance (single building, cluster of buildings) and a balance boundary which determines the included energy uses (e.g. heating, cooling, ventilation, hot water, lighting, appliances, IT, central services, electric vehicles, and embodied energy, etc.). It should be noticed that renewable energy supply options can be prioritized (e.g. by transportation or conversion effort, availability over the lifetime of the building or replication potential for future, etc.) and therefore create a hierarchy. It may be argued that resources within the building footprint or on-site should be given priority over off-site supply options.

The weighting system converts the physical units of different energy carriers into a uniform metric (site/final energy, source/primary energy renewable parts included or not, energy cost, equivalent carbon emissions and even energy or environmental credits) and allows their comparison and compensation among each other in one single balance (e.g. exported PV electricity can compensate imported biomass). Politically influenced and therefore possibly asymmetrically or time dependent conversion/weighting factors can affect the relative value of energy carriers and can influence the required energy generation capacity.

The balancing period is often assumed to be one year (suitable to cover all operation energy uses). A shorter period (monthly or seasonal) could also be considered as well as a balance over the entire life cycle (including embodied energy, which could also be annualized and counted in addition to operational energy uses).

The energy balance can be done in two balance types: 1) Balance of delivered/imported and exported energy (monitoring phase as self-consumption of energy generated on-site can be included); 2) Balance between (weighted) energy demand and (weighted) energy generation (for design phase as normally end users temporal consumption patterns -e.g. for lighting, appliances, etc.- are lacking). Alternatively a balance based on monthly net values in which only residuals per month are summed up to an annual balance is imaginable. This can be seen either as a load/generation balance or as a special case of import/export balance where a “virtual monthly self-consumption” is assumed. 

Beside the energy balance, Net ZEBs can be characterized by their ability to match the building's load by its energy generation (load matching) or to work beneficially with respect to the needs of the local grid infrastructure (grind interaction). Both can be expressed by suitable indicators which are intended as assessment tools only.

The information is based on the publications,[8][9] and [10] in which deeper information could be found.

http://www.nrel.gov/sustainable_nrel/pdfs/44586.pdf

http://whatis.techtarget.com/definition/net-zero-energy-building

http://books.google.co.in/books?id=ygdAO6_mOCgC&pg=PA205&lpg=PA205&dq=definition+of+%22near+zero+energy+buildings%E2%80%9D&source=bl&ots=YU0Fsd-PV9&sig=70vVcdBy7lsWhWpoeEeFe_WB7sY&hl=en&sa=X&ei=9Bk9VP7UBYehugTt0IGgDw&ved=0CFUQ6AEwCQ#v=onepage&q=definition%20of%20%22near%20zero%20energy%20buildings%E2%80%9D&f=false

http://www.energysector.in/energy-efficiency-news/india-s-first-zero-energy-building-indira-paryavaran-bhawan

http://www.pace-d.com/wp-content/uploads/2013/04/PACE-D-TA-NZEB-Seminar-Background-Note.pdf

http://www.suncarrieromega.com/Net-Zero-Energy-Building-SolarNovusToday.asp

http://switchboard.nrdc.org/blogs/rkhosla/jugaad_urbanism_near-zero_ener.html

http://www.outbackpower.com/downloads/case_studies/pdf/malankara.pdf

http://www.clancy-global.com/pdf/Vol%201%20-%20Case%20Study%20-%20Zero%20Energy%20Building.pdf

file:///C:/Users/shashi/Downloads/lwptBMEr65daqjk4dzfMqA9bsrdaIoMua3ccDhJ0amZGK0oyf2dfy6.pdf

Dear Shanker Lal Shrivastava ,

Thanks for your comprehensive reply .  I need time to get acquainted with the sources you sent me to comment on them

Best regards

Savov

Dear Shanker Lal Shrivastava ,

This File  is on your PC

file:///C:/Users/shashi/Downloads/lwptBMEr65daqjk4dzfMqA9bsrdaIoMua3ccDhJ0amZGK0oyf2dfy6.pdf

One CEN answer to your questions is in the Technical Report 15615 on the standard EN 15603. Thex propose that an NZEB should comply to 4 criteria. See annex G of the attached document

Dear Claude-Alain Roulet,

This CEN answer is a perfect answer 

This document is very important

Thank you 

Savov

Dear ResearchGate-r,

I'm interested in the national policy of your country in the field of energy efficiency and near Zero Energy Building (nZEB).  Bulgarian definition of nZEB is presented in the EC notification.     It is interesting to see the differences and to meet with your comments about this

If you want you can visit

http://ec.europa.eu/enterprise/tris/bg/search/?trisaction=search.detail&year=2014&num=432I

http://ec.europa.eu/enterprise/tris/bg/search/?trisaction=search.detail&year=2014&num=433

expect your comments

Savov

According to these documents Bulgarian definition is

29. "Building with near-zero energy consumption" is a building which meets all of the following conditions:

а) energy consumption of the building, determined as primary energy, corresponds to Class A of the scale of energy consumption classes for the relevant type of buildings;

b) no less than 55% of the necessary (delivered) energy for heating, cooling, ventilation, hot water for household purposes and lighting is energy from renewable sources located on-site at the level of the building or close to the building."

Savov

Dear Ivica Toljan,

I think, not always high energy efficiency resulting in "Building with near-zero energy consumption"

Main decision is where the energy required to maintain comfortable living reduces the use of fossil fuels to zero

According to Bulgarian documents definition of "Building with near-zero energy consumption" is

"Building with near-zero energy consumption" is a building which meets all of the following conditions:

а) energy consumption of the building, determined as primary energy, corresponds to Class A of the scale of energy consumption classes for the relevant type of buildings;

b) no less than 55% of the necessary (delivered) energy for heating, cooling, ventilation, hot water for household purposes and lighting is energy from renewable sources located on-site at the level of the building or close to the building."

Best regards

Savov

Dear Dr. Rossen,

The concept in Brazil is associated with energy efficiency and is summarized in: "all the electricity needed to power a building is produced by itself".

The work of the Federal University of Santa Catarina, deals with propositions for near zero energy:

http://cb3e.ufsc.br/sites/default/files/ProposicaoEstrategiasEnergiaZero_28082013.pdf

Best Regards,

Vanessa

Dear Vanessa,

Thank you for yuor kindly answer

I`ll read it with enterest

Best regards

Savov

Dear Vanessa, Claude, Eraldo, Ivica, Shanker Lal,

You are a dreamer,

and you are an achiever.

May you dream and achieve bigger feats,

with every passing year.

All the best for the new year 2015.

Savov

https://ec.europa.eu/energy/en/topics/energy-efficiency/buildings/nearly-zero-energy-buildings

http://www.bpie.eu/documents/BPIE/publications/LR_nZEB%20study.pdf