Towards Zero Energy Buildings Bjarne W. Olesen, Technical University - - PowerPoint PPT Presentation

Towards Zero Energy Buildings

Bjarne W. Olesen, Technical University of Denmark Per Heiselberg, Aalborg University

Outline

• 0:00 European and US actions towards ZEB (Bjarne)
• 0:12 European Definition of nZEB (Per)
• 0:17 Experience with low energy buildings (Per)
• 0:25 Energy Efficient Ventilation of Buildings (Per)
• 0:40 Energy efficient Heating and Cooling of buildings

(Bjarne)

• 0:55 Q&A

European and US actions towards ZEB

• Building codes and standards
• Energy performance directive
• Renewable energy requirements
• Requirements to products and components

Role of the Building Sector ¨’

• 40 % of EU’s energy use
• 36 % of EU’s CO2 emissions
• Cost-effective energy savings potential: ~30 % by

2020

• 9 % of GDP, 8 % of employment and
• €2 trillion annual turnover

4/12

Comprehensive set of legislation to enhance energy efficiency



. Directive for the taxation of energy products and

electricity

. Energy end-use efficiency and energy

services Directive Services

. Directive on the promotion of cogeneration

Generation Buildings

. Energy performance of buildings Directive

(EPBD)

. Directive establishing a framework for the setting of eco-

design requirements for energy-using products (implementing directives for e.g. boilers, refrigerators, freezers and ballasts for fluorescent lighting Eco-Design

. Directives for labelling of e.g. electric ovens, air-

conditioners, refrigerators and other domestic appliances

. Regulation of Energy Star labelling for office equipment

Product Labelling Taxation

5/14

The 20-20-20 EU policy by 2020

Greenhouse gas levels Energy consumption Renewables in energy mix

• 20%
• 20%

100%

20%

8,5%

Required reductions in energy use in European countries 2020 in relation to 2005

Directive 2009/28/EC (Renewable Energy Directive 2009) of the European Parliament and of the Council of 23 April 2009 on the promotion of the use of energy from renewable sources

National overall targets for the share of energy from renewable sources in gross final consumption of energy in 2020

• Hungary

4,3 % 13 %

• Malta

0,0 % 10 %

• Netherlands 2,4 %

14 %

• Austria

23,3 % 34 %

• Poland

7,2 % 15 %

• Portugal

20,5 % 31 %

• Romania

17,8 % 24 %

• Slovenia

16,0 % 25 %

• Slovak Republic6,7 %14 %
• Finland

28,5 % 38 %

• Sweden

39,8 % 49 %

• United Kingdom 1,3 % 15 %

Belgium

2,2 13 % Bulgaria 9,4 16 % Czech Republic 6,1 13 % Denmark 17,0 30 % Germany 5,8 18 % Estonia 18,0 25 % Ireland 3,1 16 % Greece 6,9 18 % Spain 8,7 20 % France 10,3 23 % Italy 5,2 17 % Cyprus 2,9 13 % Latvia 32,6 40 % Lithuania 15,0 23 % Luxembourg 0,9 11 %

2005-2020 2005-2020

Part of renewable energy sources (wind and bio-fuel) in Denmark

Comprehensive set of legislation to enhance energy efficiency



. Directive for the taxation of energy products and

electricity

. Energy end-use efficiency and energy

services Directive Services

. Directive on the promotion of cogeneration

Generation Buildings

. Energy performance of buildings Directive

(EPBD)

. Directive establishing a framework for the setting of eco-

design requirements for energy-using products (implementing directives for e.g. boilers, refrigerators, freezers and ballasts for fluorescent lighting Eco-Design

. Directives for labelling of e.g. electric ovens, air-

conditioners, refrigerators and other domestic appliances

. Regulation of Energy Star labelling for office equipment

Product Labelling Taxation

11/14

Energy Performance of Buildings Directive – EPBD (2002/91/EC)



Requirements - for Member States to specify and implement:

• An integrated methodology to rate the energy performance of

buildings

• Minimum energy performance standards for new and for

existing buildings that undergo major renovation

• Energy performance certificates for buildings
• Regular inspections of boilers and

air-conditioning systems 12/14

The effect og building regulations

US developments towards ZEB

• Often driven by private organization like

ASHRAE

• Very different from state to state
• Several states are reffering to ASHRAE standard

90.1

• California has the most strict criteria in their

California Building Standards Code ,Title 24

• DOE (department of Energy) want to have a

national definition of ZEB

ASHRAE’s contribution to ZEB

• Standards
• Handbooks
• Advange Energy Design Guides

Major Standards under Review/Revision

ASHRAE-Energy Performance Standards

• ANSI/ASHRAE/IES Standard 90.1-2013 -- Energy

Standard for Buildings Except Low-Rise Residential Buildings

• ANSI/ASHRAE Standard 90.2-2007 - Energy Efficient

Design of Low-Rise Residential Buildings

• ANSI/ASHRAE/IES 100-2015 - Standard 100-2006.

Energy Efficiency in Existing Buildings

• ANSI/ASHRAE/USGBC/IES/ICC 189.1-2014 Standard

for the Design of High-Performance, Green Buildings Except Low-Rise Residential Buildings

ANSI/ASHRAE/IES Standard 90.1-2013 -- Energy Standard for Buildings Except Residential Buildings

20

Source: Pacific Northwest National Laboratory

Advanced Energy Design Guides: 522,000 in circulation

Four 50% AEDGs Being Implemented

• 50% Grocery Stores

– Quick Serve Restaurants – Places of Assembly

• Under Discussion
• Net Zero

– K-12 Schools (2) – Quick Serve Restaurants – Places of Assembly – “Net Zero Ready” Guidance

www.ashrae.org/freeaedg

Building Energy Quotient

• Free submissions offered to qualified ASHRAE

members until Nov. 30, 2014

• Expanded to allow submissions by professional

engineers in addition to ASHRAE-Certified Building Energy Assessment Professional (BEAP) or Building Energy Modeling Professional (BEMP)

• Updated In Operation Workbook with more

consistent, streamlined procedures

• EPA-Energy Star rating???

ZEB Concept

Over the course of a year, if the on-site renewable energy produced ≥ the energy consumed within the boundary, it is considered a ZEB

23

Site Energy (n)ZEB

A building where the actual annual delivered energy ≤ on-site renewable exported energy as measured at the site.

24

Source Energy (n)ZEB

A building where the actual annual delivered energy ≤ on-site renewable exported energy as measured at the building site and converted to source energy.

25

Zero Energy Cost Building

A building where the actual annual energy costs are zero.

26

(Net) Zero Energy Building (ZEB) Definition

An energy-efficient building, where on a source energy basis, the actual annual delivered energy is less than or equal to the

• n-site renewable exported energy.

27

EUROPEAN DEFINITION OF NZEB

Per Heiselberg

TIMELINE OF KEY EU LEGISLATION AFFECTING ENERGY USE IN BUILDINGS

THE EU- DIRECTIVE ON ENERGY PERFORMANCE OF BUILDINGS 2002 (IMPLEMENTED IN DK IN 2006)

THE GENERAL FRAMEWORK FOR A METHODOLOGY OF CALCULATION OF THE INTEGRATED ENERGY PERFORMANCE OF BUILDINGS;

• The application of minimum requirements on the energy

performance of new buildings;

• The application of minimum requirements on the energy

performance of large existing buildings that are subject to major renovation;

• Energy certification of buildings
• Regular inspection of boilers and of air-conditioning

systems in buildings and in addition an assessment of the heating installation in which the boilers are more than 15 years old.

EU DIRECTIVE ON THE ENERGY PERFORMANCE OF BUILDINGS

Definition

• The amount of energy actually consumed or estimated

to meet the different needs associated with a standardised use of the building, which may include, inter alia, heating, hot water heating, cooling, ventilation and lighting.

• This amount shall be reflected in one or more numeric

indicators which have been calculated, taking into account insulation, technical and installation characteristics, design and positioning in relation to climatic aspects, solar exposure and influence of neighbouring structures, own-energy generation and

• ther factors, including indoor climate, that influence

the energy demand

ENERGY PERFORMANCE REQUIREMENTS TO BE SET WITH A VIEW TO ACHIEVING COST OPTIMAL LEVELS USING A COMPARATIVE METHODOLOGY FRAMEWORK

• Cost optimal performance is defined as the energy performance in terms of

primary energy leading to minimum life cycle cost.

EDBP RECAST ESTABLISHED THE TARGET OF NEARLY ZERO ENERGY BUILDINGS (NZEB) FOR ALL NEW BUILDINGS

• By 31 dec 2020, all new buildings are nearly zero energy buildings
• After 31 dec 2018, public authorities that occupy and own a new building shall

ensure that the buildings is a nearly zero energy building

EPBD RECAST

• TARGETS FOR COST OPTIMAL AND NZEB

EDBP RECAST

• DEFINITION OF NEARLY ZERO ENERGY

BUILDINGS

In the directive “nearly zero energy buildings ” means a building that has a very high energy 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 Definition of “a very high energy performance ” and “significant extent

• f renewables” are defined by member states

NEARLY ZERO ENERGY BUILDING DEFINITION

NEARLY ZERO ENERGY BUILDING DEFINITION SHALL BE BASED ON DELIVERED AND EXPORTED ENERGY ACCORDING TO EPBD RECAST AND EN 15603:2008 ENERGY USE IN THE BUILDINGS INCLUDES ENERGY USED FOR HEATING, COOLING, VENTILATION, HOT WATER, LIGHTING AND APPLIANCES. THIS IS NEEDED FOR CALCULATION OF EXPORTED ENERGY OR TO ANALYZE LOAD MATCHING AND GRID INTERACTION OF NZEB

Total energy use

• f the building

Delivered energy Exported energy Building site = system boundary of delivered and exported energy

System boundary of building technical systems

BUILDING NEEDS Heating Cooling Ventilation DHW Lighting Appliances 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 Heating en. Electricity Cooling en. Energy use SB Cooling en. Heating en. Energy need SB

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

EXPERIENCE WITH LOW ENERGY BUILDINGS

Per Heiselberg

ENERGY USE HIGHER THAN EXPECTED

Based on 230.000 single family houses with energy labelling. Preliminary results not yet validated or published

Reference: Kirsten Gram-Hanssen, SBi 2015

HOME FOR LIFE, LYSTRUP, DENMARK

Home for life – Energy Concept

Home for life – Energy balance

60

Energy production solar thermal and solar cells

• 33

Hot water and heating

• 14

Electricity household

• 8

Electricity technique

Energy need and production from solar [kwh/m2/year]

EXPERIENCES RELATED TO ENERGY USE AND PRODUCTION

THE MOST IMPORTANT DEVIATIONS:

• Energy use for heating higher than expected
• Electricity use for heat pump higher than expected
• Electricity use for control system higher than expected
• Energy use DHW lower than expected
• Electricity use for appliances and plug loads lower than expected.
• Production from solar thermal system as expected
• Production from PV as expected

Reference: Esbensen, 2012

1. Measured 2. As 1, corrected for weather 3. As 2, corrected for indoor temperature 4. As 3, corrected for lower person load 5. As 4, corrected for domestic electricity use 6. As 5, corrected for air tightness

• 7. As 6, corrected for less efficient heat recovery
• 8. As 7, corrected for use of solar shading
• 9. As 8, corrected for measuring equipment and screens
• 10. As 9, corrected for DHW use
• 11. As 10, corrected for efficiency of heat pump
• 12. Predicted energy use

Reference: Esbensen, 2012

RELATIVE IMPORTANCE OF DIFFERENT ASPECTS

Reference: Esbensen, 2012

Overheating – living room

Reference: Esbensen

32% 24% 32% 10% 2%

Living year 1

58% 26% 13% 1% 2%

Living year 2

59% 20% 14% 1% 6%

Sleeping, year 1

66% 18% 13% 1% 2%

Sleeping, year 2

Reference: VELUX og Esbensen

IMPACT OF IMPROVED CONTROL AND OPERATION

WHY DO WE FACE THESE CHALLENGES IN HIGH PERFORMANCE BUILDINGS?

IT IS NOT POSSIBLE TO REACH GOALS THROUGH MORE

• Envelope insulation, Building airtightness, Ventilation heat recovery,

WHICH ARE ROBUST TECHNOLOGIES WITHOUT USER INTERACTION NEW MEASURES NEEDS TO BE INCLUDED

• Demand controlled ventilation
• Shading for solar energy control
• Shading for daylighting control
• Lighting control
• Window opening

ALL TECHNOLOGIES:

• Where performance is very sensitive to control
• Which involve different degree of user interaction
• Whose function and performance are difficult for users to understand

WHY DO WE FACE THESE CHALLENGES IN HIGH PERFORMANCE BUILDINGS?

THE PRIMARY OBJECTIVE OF USERS IS FULLFILLMENT OF THEIR NEEDS (INDOOR ENVIRONMENT) AND THEY WILL ALWAYS ADJUST CONTROLS ACCORDINGLY. THIS OFTEN LEADS TO HIGHER ENERGY USE AND POORER INDOOR ENVIRONMENT THAN EXPECTED. AUTOMATIC CONTROL SHOULD BE BETTER ADAPTED TO THE FULLFILMENT OF USER NEEDS

PER HEISELBERG

ENERGY EFFICIENT VENTILATION OF HIGH PERFORMANCE BUILDINGS

ENERGY EFFICIENT VENTILATION OF HIGH PERFORMANCE BUILDINGS

ENERGY DEMAND IN TYPICAL OFFICE BUILDING

Conditions

U-value: 1,5 W/m²K, g-value: 0,60, Lt-value: 0,70 SFP: 2,1 kJ/m³ Light control: Manual Thermal mass: Light 30 % window area in relation to floor area Infiltration 0,3 h-1

Cooling Heating Lighting Ventilation Misc. Energy demand distribution Total energy demand 96 kWh/m²

ADDITIONAL CHALLENGES IN HIGH PERFORMANCE BUILDINGS

The current development towards nearly -zero energy buildings have lead to: an increased need for cooling – not only in summer but all year

• Increased potential for using the cooling potential of outdoor air

An reduction of Electricity use for air transport becomes increasingly important

• Increased use of natural/hybrid ventilation
• Distribution of cold air to rooms without creating discomfort
• Effective decentralized ventilation solutions

SIX DIFFERENT AIR DISTRIBUTION SYSTEMS

• Tested in the same geometry and with the same load

pvn@civil.auc.dk

qo - ∆To Design Chart

WIDEX/WESSBERG A/S

WIDEX/WESSBERG A/S

SOLBJERGSKOLEN SOUTHWEST OF ÅRHUS

SYSTEM PRINCIPLE

DRAUGHT RISK

• Winter condition: supply air temperature -8 oC,

ACH =4

DR <20% ISO 7730

VENTILATION SOLUTIONS

Building Use Outdoor Climate Building Design

IAQ

Thermal Comfort Internal loads Micro- climate

Natural ventilation Mechanical ventilation Air Conditioning Hybrid ventilation

Occupant

Profile

RATIONALE FOR HYBRID VENTILATION

• HAS ACCESS TO BOTH VENTILATION MODES

IN ONE SYSTEM, EXPLOITS THE BENEFITS OF EACH MODE AND CREATES NEW OPPORTUNITIES FOR FURTHER OPTIMISATION AND IMPROVEMENT OF THE OVERALL QUALITY OF VENTILATION.

• FULFILS THE HIGH REQUIREMENTS ON

INDOOR ENVIRONMENTAL PERFORMANCE AND THE INCREASING NEED FOR ENERGY SAVINGS AND SUSTAINABLE DEVELOPMENT.

• RESULTS IN HIGH USER SATISFACTION

BECAUSE OF THE HIGH DEGREE OF INDIVIDUAL CONTROL AS WELL AS A DIRECT AND VISIBLE RESPONSE TO USER INTERVENTIONS.

• OFFERS AN INTELLIGENT AND ADVANCED

VENTILATION SOLUTION FOR THE COMPLEX BUILDING DEVELOPMENTS OF TODAY, THAT IS USER TRANSPARENT AND SUSTAINABLE.

HYBRID VENTILATION STRATEGIES

Alternating or combined natural and mechanical ventilation

– This principle is based on a combination of two fully autonomous systems where the control strategy consists of switching between or combining both systems. – It covers fx systems with natural ventilation in the intermediate seasons and mechanical ventilation during midsummer and/or midwinter or it covers systems with mechanical ventilation for workstations during occupied hours and natural ventilation for building and night cooling.

INSTITUTE OF DEVELOPMENT ECONOMIES (JETRO), CHIBA, J

Courtesy of:

• Dr. Tomoyki Chikamoto, Nikken Sekkei Ltd, Japan

Heat from Task Zone Supply fan unit for Ambient Zone

Fresh air Ambient Zone Task Zone

CH C

EA (Exhaust Air) OA (Outside Air) Personal supply outlet for Task Zone (D air to human body) irect supply of fresh

Effective exhaustion of heat and pollutant

CH C

OA Personal AC system for Task Zone Higher temp. upply jet

s

Under-floor AC system for Ambient Zone

20℃ 22℃ 22℃ 28℃ 26℃

High IAQ and thermal comfort

Pollutant from Task Zone

26℃ 30℃

HYBRID VENTILATION AND AIR CONDITIONING SYSTEM

Automatically controlled window

• This opening is also used for smoke exhaust
• pening in case of fire

Ambient supply unit Task supply unit

• Air volume and direction are

easily changed by each user

HYBRID VENTILATION AND AIR CONDITIONING SYSTEM

Fresh air Ambient Zone Task Zone

CH C

EA (Exhaust Air) OA (Outside Air)

CH C

OA

Air volume and direction are easily changed by each user. Task supply unit is detachable. Ambient zone is controlled mildly by central BA system for energy saving. Task zone is controlled by each one’s choice for human’s comfort. Warm air Cool air

CONTROL OF HYBRID VENTILATION AND AIR CONDITIONING SYSTEM

HYBRID VENTILATION STRATEGIES

STACK AND WIND SUPPORTED MECHANICAL VENTILATION

– This principle is based on a mechanical ventilation system, which makes optimal use of natural driving forces. – It covers mechanical ventilation systems with very small pressure losses where natural driving forces can account for a considerable part of the necessary pressure difference.

N M

Mediå School, Grong, Norway

Courtesy of: Professor Per Olaf Tjelflaat, Norwegian University for Science and Technology, Trondheim, Norway

AIR SUPPLY SYSTEM

AIR EXHAUST SYSTEM

Mediå School, Grong, Norway

LOW PRESSURE LOSS IN SYSTEM

• VENTILATION SUPPLY ABOUT 35 PA

– Filter about 15 pa – Heat recovery about 10 pa – Heating about 5 pa

• VENTILATION EXHAUST ABOUT 20 PA

– Heat recovery about 12 pa

TOTAL PRESSURE LOSS WINTER ABOUT 55 PA TOTAL PRESSURE LOSS SUMMER ABOUT 28 PA PRESSURE LOSS SUMMER (WITHOUT FILTER) ABOUT 13 PA

Energy efficient Heating and Cooling of buildings

• Low temperature Heating-High Temperature Cooling
• Water based systems
• Radiant heating and cooling ceiling panels
• Thermo Active Building Systems (TABS)
• Chilled beams
• Floor heating and cooling

Low-Temperature heating High-Temperature Cooling

• Heat exchange through large surfaces

(floor, ceiling, walls)

• Supply water temperatures:

– Heating: 25 – 40 °C – Cooling: 16 – 23 °C (temperature limited by dew-point to avoid condensation)

• Wide range of systems, solutions both for

residential and non-residential buildings

74

Sus ustain tainability ability

75

• Higher efficiency of boilers and chillers
• Lower distribution looses
• Better use of renewable energy sources

– Ground heat exchangers – Waste heat from processes – Dry coolers – Heat pumps

• Low energy consumption for

circulation

• Low exergy

CONCEPTS OF RADIANT HEATING AND COOLING SYSTEMS

• Minimum 50% heat exchange by radiation
• Heating - cooling panels
• Surface systems
• Embedded systems
• Most recent development is the increasing

application world wide.

Suspended cooled ceilings

System stem type pes

• Water as the heat carrier
• Heat exchange is > 50% radiant
• Different installation concepts

(thermally coupled or insulated form the building structure)

78

THERM RMO ACTIVE BUILD ILDIN ING G SYST STEM EMS S (TABS BS)

• Trend started in nineties in Switzerland, typically used in Europe
• Suitable primarily for sensible cooling and for base heating
• Installed in the centre of concrete slab between the reinforcements
• Diameter of the pipes varies between 17 and 20 mm
• The distance between pipes is within the range 150 - 200 mm
• Installed during the main building construction with prefabricated slabs.

Reinforcement Floor Concrete Pipes Window Room Room

Concept of Thermo Active Building Systems

Concept of Thermo Active Building Systems (TABS)

EXAMPLE OF INTERNAL CONDITIONS WITH THERMAL SLAB

20 21 22 23 24 25 26 27 28 29 30 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00 20.00 21.00 22.00 23.00 0.00 TEMPERATURE [°C]

• 1
• 0.5

0.5 1 PREDICTED MEAN VOTE

T floor PMV T air T mr T water return T ceiling

COMBINAT ATION N WITH LOW ENERG RGY Y SOURC RCES ES

UPONOR Corporation (2010)

• Heating supply temp. : 25 - 40°C
• heat pumps
• condensing boiler
• ground coupling
• waste heat
• solar energy
• Cooling supply temp. : 16 - 23°C
• reversible heat pump
• ground coupling
• free cooling
• air cooled chillers

82

Day Night Cooling method Ground water Geothermal heat/coolth Night air Cooling unit

Add ddit ition ional al be bene nefi fits ts – la large ge atri riums ums and nd foyer ers

83

• The under-floor cooling system directly removes solar heat gains
• Minimum of such gains influences air temperature
• Comfortable floor surface temperature is maintained at the same time

Airport Bangkok

Airport Bangkok

June 30 2008

Terminal building

Balanced Office Building Aachen, Germany

• Gross floor area 2,151 m²
• 4 storeys
• Efficiently insulated

external envelope

• Ground-coupled heating

and cooling with TABS

• Ventilation system with

heat recovery

• Daylight-controlled

lighting

• Rainwater collection for

use in toilet flushing

Energy concept

cooling period

5000 10000 15000 20000 25000 30000 35000 Heizung Kühlung Lüftung Beleuchtung Pumpen Warmwasser Summe Yearly energie costs [€/m²a] Bestand BOB.1

Energy efficiency

94 % energy saving compared with conventional cooling 60 % energy saving for lighting by daylight steering The need of energy for heating, cooling, air- ventilation lighting and warm water is 27,8 kWh/m² per year Energy costs per m², per year: 2,7 EUR, per month 22,5 Cent

Office Building in Madrid, Spainain

91

• 16 000 m2
• Natural & Mechanical ventilation
• External solar shading & green

facade

• TABS combinned with free cooling

(covers 40-50 kWh/m2)

(kWh/m²y)

Actual

CTE - MADRID % Heating + DHW 27,35 77,00

• 64,5

Cooling 12,58 85,00

• 85,2

Lighting 11,37 34,00

• 66,6

Total 51,30 196,00

• 73,8

Energy use

Office Building in Madrid, Spain

92

Chilled Beams

Water based distribution

Chilled Beams

Chilled Beams

Water based distribution

Low Exergy Hydronic Radiant Heating and Cooling

Why?

• Water based systems
• Low temperature heating - High temperature cooling
• More economical to move heat by water:

– Greater heat capacity than air – Much smaller diameter pipes than air-ducts – Electrical consumption for circulation pump is lower than for fans

• Lower noise level
• Less risk for draught
• Lower building height for TABS
• Higher efficiency of energy plant
• But

– Reduced capacity? – Acoustic? – Latent load?

VENTILATIVE COOLING

P E R H E I S E L B E R G D E P A R T M E N T O F C I V I L E N G I N E E R I N G

DEFINITION OF VENTILATIVE COOLING

VENTILATIVE COOLING IS APPLICATION (DISTRIBUTION IN TIME AND SPACE) OF VENTILATION AIR FLOW TO REDUCE COOLING LOADS IN BUILDINGS VENTILATIVE COOLING UTILIZES THE COOLING AND THERMAL PERCEPTION POTENTIAL (HIGHER AIR VELOCITIES) OF OUTDOOR AIR IN VENTILATIVE COOLING THE AIR DRIVING FORCE CAN BE NATURAL, MECHANICAL OR A COMBINATION

VENTILATIVE COOLING IS A SOLUTION

THE DEVELOPMENT TOWARDS ”NEAR ZERO ENERGY BUILDINGS” HAS RESULTED IN AN INCREASED NEED FOR COOLING – NOT ONLY IN SUMMER BUT MOST OF THE YEAR! VENTILATIVE COOLING CAN BE AN ATTRACTIVE AND ENERGY EFFICIENT PASSIVE SOLUTION TO REDUCE COOLING AND AVOID OVERHEATING.

• Ventilation is already present in most buildings through mechanical and/or

natural systems using opening of windows

• Ventilative cooling can both remove excess heat gains as well as increase air

velocities and thereby widen the thermal comfort range.

• The possibilities of utilizing the free cooling potential of low temperature
• utdoor air increases considerably as cooling becomes a need not only in the

summer period.

POTENTIAL AND LIMITATIONS

OUTDOOR CLIMATE POTENTIAL

• Outdoor temperature lower than the thermal comfort limit in large part of the

year in many locations

• Especially night temperatures are below comfort limits
• Natural systems can provide “zero” energy cooling in many buildings

LIMITATIONS

• Temperature increase due to climate change might reduce potential
• Peak summer conditions and periods with high humidity reduce the potential
• An urban location might reduce cooling potential (heat island) as well as

natural driving forces (higher temperature and lower wind speed). Elevated noise and pollutions levels are also present in urban environments

• Building design, fire regulations, security are issues that might decrease the

use of natural systems

• High energy use for air transport limit the potential for use of mechanical

systems

Annex 62 Ventilative Cooling

IEA EBC Annex 62 Ventilative Cooling

Annex 62 Ventilative Cooling

Annex Objectives

• To analyse, develop and evaluate suitable methods and tools for

prediction of cooling need, ventilative cooling performance and risk

• f overheating in buildings that are suitable for design purposes.
• To give guidelines for integration of ventilative cooling in energy

performance calculation methods and regulations including specification and verification of key performance indicators.

• To extend the boundaries of existing ventilation solutions and their

control strategies and to develop recommendations for flexible and reliable ventilative cooling solutions that can create comfortable conditions under a wide range of climatic conditions.

• To demonstrate the performance of ventilative cooling solutions

through analysis and evaluation of well-documented case studies.

Annex 62 Ventilative Cooling

Annex Outcome

• Guidelines for energy-efficient reduction of the risk of
• verheating by ventilative cooling
• Guidelines for ventilative cooling design and operation in

residential and commercial buildings

• Recommendation for integration of ventilative cooling in

legislation, standards, design briefs as well as on energy performance calculation and verification methods

• New ventilative cooling solutions including their control

strategies as well as improvement of capacity of existing systems

• Documented performance of ventilative cooling systems in

case studies

Annex 62 Ventilative Cooling

Annex Leadership

• Participating countries

– Austria, Belgium, China, Denmark, Ireland, Italy, Japan, Netherlands, Norway, Portugal, Switzerland, UK, USA

• Operating Agent:

– Denmark, represented by Per Heiselberg, Aalborg University

• Subtask A:

– Leader: Switzerland, represented by Fourentzos Flourentzou, ESTIA – Co-leader: Italy, represented by Annamaria Belleri, EURAC

• Subtask B:

– Leader: Austria, represented by Peter Holzer, IBRI – Co-leader: Denmark, represented by Theofanis Psomas, AAU

• Subtask C:

– Leader: China, represented by Guoqiang Zhang, Hunan University – Co-leader: Ireland, represented by Paul O’Sullivan, CIT

DIFFUSE CEILING VENTILATION

P E R H E I S E L B E R G D E P A R T M E N T O F C I V I L E N G I N E E R I N G

COOLING IN OFFICES AND EDUCATIONAL BUILDINGS

WITH HIGH INSULATION AND AIR TIGHTNESS LEVELS ALWAYS A COOLING NEED DURING OCCUPIED HOURS EVEN IN THE WINTER SEASON COOLING IS NOT A NEW TECHNOLOGY, BUT THE NEED FOR COOLING IS INCREASING AND MORE EFFICIENT SYSTEMS HAVE TO BE DEVELOPED TO FULFILL FUTURE ENERGY REQUIREMENTS APPLICATION OF THE FREE COOLING POTENTIAL OF OUTDOOR AIR IS WIDELY USED IN MECHANICAL VENTILATION SYSTEMS, BUT HIGH AIR FLOW RATES ARE NEEDED IN WINTER BECAUSE OF DRAUGHT RISK LEADING TO RELATIVELY HIGH ENERGY USE FOR AIR TRANSPORT

WHAT IS DIFFUSE CEILING VENTILATION

THE SPACE ABOVE A SUSPENDED CEILING IS USED AS A PLENUM AND FRESH AIR IS SUPPLIED TO THE OCCUPIED ZONE THROUGH PERFORATED SUSPENDED CEILING.

THE PRINCIPLE

Rockfon / Troldtekt ceiling Ecophon ceiling Fully diffuse ceiling

SIX DIFFERENT AIR DISTRIBUTION SYSTEMS

• Tested in the same geometry and with the same load

pvn@civil.auc.dk

QO - ∆TO DESIGN CHART

WIDEX/WESSBERG A/S

WIDEX/WESSBERG A/S

SOLBJERGSKOLEN SOUTHWEST OF ÅRHUS

SYSTEM PRINCIPLE

DRAUGHT RISK

• Winter condition: supply air temperature -8 oC, ACH =4

DR <20% ISO 7730

HEAT LOAD LOCATION

Evenly distributed Center Front side Back side

VELOCITY DISTRIBUTION

DRAUGHT RISK

2 4 6 8 10 12 14 16 18 20 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 DR [%] Distance from inlet [m] Evenly Center Front side Back side

ROOM HEIGHT

2.335 m 3.0 m 4.0 m

VELOCITY DISTRIBUTION

2.335 m 3.0 m 4.0 m

DRAUGHT RISK

2 4 6 8 10 12 14 16 18 20 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 DR [%] Distance from inlet [m] 2.335 m 3.0 m 4.0 m

DIFFUSE CEILING OPENING AREA

100% DF 18% DF

VELOCITY DISTRIBUTION

100% DF 18% DF

DRAUGHT RISK

2 4 6 8 10 12 14 16 18 20 1 2 3 4 5 DR [%] Distance from inlet [m] 0.1 m 0.6 m 1.1 m 1.7 m 2 4 6 8 10 12 14 16 18 20 1 2 3 4 5 DR [%] Distance from inlet [m] 0.1 m 0.6 m 1.1 m 1.7 m

100% DF 18% DF

CONCLUSION

Low draught risk in the occupied zone even, when supplying air at temperatures below 0Co Air distribution and draught risk dependent on heat load location, ceiling height, area and location of supply. Very low vertical temperature gradient in the room with diffuse celling supply Low radiant temperature asymmetry and no clear radiation cooling potential of diffuse ceiling, due to low conductivity Very low pressure drop across diffuse ceiling (less than 5 Pa)