Energy Efficient Office Buildings

AuthorsDipl.-Ing., Dipl.-Wirtsch.-Ing. Jörg Probst, Gertec Ingenieurgesellschaft, EssenDipl.-Ing. Klaus Beck, Architekt und Stadtplaner, BielefeldDipl.-Ing. Patrick Jung, Jung Ingenieure, Köln

Edition, Concept, Realization2008 Gertec Ingenieurgesellschaft GmbH

Martin-Kremmer-Str. 12, 45327 Essen www.gertec.de

Design Petra Dietrich, München

©

Structured Project Planning 3

Legal Requirements for Office Buildings 4

Building Type and Amenity Standards 5

Architecture and Design 8

Examples > Best Practice 10

Concrete Core Activation 13Solar Energy„Green IT“

Influential FactorsControlling the Energy Needs 14

Efficient Lighting for Offices 16

Integral Planning and Technical Design 18

Optimizing Office Building EnergyHouseholds and Utilization Values

Builders taking on the challenge of erec-ting a modern, innovative and ground-breaking office building today with theobjective of providing 1,000 m² or even2,000 m² of usable floor space find them-selves confronted with a complex task.

Numerous factors have to be taken intoaccount. In the very early stages of theproject planning process, comprehensivedecisions have to be made that define thequalities and capabilities of a building foryears to come. This brochure offers a gui-deline for this decision making process inreference to the targeted building quality,amenities and technical equipment. Itmakes transparent the various ap-proaches to solutions, the parameters andinterdependencies. The aim of the authorsis not only to come up with the one andonly perfect solution, but also to high-light how to mindfully make the best useof the design options and general condi-tions.

The implementation of the EU Guideline(Energy Performance of Buildings Direc-tive EPBD) in the Energy Savings Act(EnEV) introduces new, partially vastreaching general conditions that have a

substantial impact on architectural de-sign, heating-ventilation-air conditioning(HVAC) concepts and the operation ofbuildings. These novel requirements alsotranslate into the emergence of new ob-jectives and control factors.

Given the undercut of the maximal solarinflux values, as well as the optimizationof internal storage capacities and otherregulations, office buildings with facadesmade entirely of glass, lightweight inte-rior walls and improvident interior designplanned for lighting and PCs, which arestill quite common today, are no longerin compliance with the state-of-the-artand also not with pertinent laws.

Consequently architects are now calledupon to team up with builders to developand implement new architectural plans,new energy concepts and new operatio-nal solutions. The first order of business,just like in any other investment processis the definition of objectives and controlfactors and to utilize same as the basisfor the conception of financial, energyand operational concepts for the futurebuilding.

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Energy ConceptEnergy Concept

Financial ConceptFinancial Concept

Operating ConceptOperating Concept

LocationLocationTopographyTopography

The Planning ProcessThe Planning Process

Architecture and DesignArchitecture and Design

Materials & Building SupMaterials & Building Suppliesplies

TechnologiesTechnologies

AdministrationAdministration

Fundamental Decision: Building Type and Amenities Standard

Target and control factors

Building with standard amenities:EUR 1,200/m²

uncooled

Building with optimized amenitiesEUR 1,400 -1,600/m²

silent cooling – concrete core activation– zone cooling

Building with luxury amenities > EUR 1,600/m²

air conditioning with humidification and de-humidification

Temperatures and humidity Air exchanges

Statutes and standards Investment and operating costs:

Heating, cooling, ventilation, lighting

Cost effectiveness analysis Investment costs

operating costs (energy, service, maintenance costs)

Subsidies

Operational management Quality control

Insulation Storage

Air tightness

Facade design

Heating energy Cooling energy

Ventilation Lighting

Administration Energy management

(dynamic data recording and needs-adequate control)

Re-powering

Structured Project Planning

The Planning Process Every building planning process beginswith the fundamental decisions pertai-ning to the building type and its ameni-ties. The chosen quality – standardamenities, optimized or luxury amenities– determines the building project budget.The options for the technical buildingamenities concepts are obviously morecomprehensive if the building is designedwith luxury amenities costing more thanEUR 1,600/m² than for buildings withstandard amenities budgeted at approx.EUR 1,200/m².

Simply structured standard buildings canusually be erected only without mecha-nical cooling given their respective bud-gets and consequently have to beequipped with such architectural andtechnical concepts that they can be usedduring hot summer months all the same.Buildings with optimized amenities,which cost anywhere from EUR 1,400 toEUR 1,600 can definitely be equippedwith silent cooling, concrete core activa-tion or zone cooling; i.e. energy optimizedconcepts.

Energy ConceptAt the beginning of the planning concept,objectives and general conditions are de-fined within the scope of the energy con-cept. Temperatures and humidity levels aswell as the ventilation volume have to bedefined in compliance with the intendeduse and requirements of the builder. Theyhave to be stipulated for the followingplanning processes. The fundamental sta-tutory requirements, such as the EnEV(Energy Savings Act), which will be effec-tive in 2009, must be factored in and bin-dingly defined for the subsequent phasesof the planning process.

An initial overview over the investmentand subsequent operating costs is obtai-ned within the scope of the energy con-cept definitions for the disciplines ofheating, cooling, ventilation and lighting.This is where the energy concept and thefinancing concept interface. The basiccost effectiveness data can now be deter-mined. Investment costs, future operatingexpenses and subsidy funding are inclu-ded in the calculation and allow buildersto realize long term cost saving measuresfor the building, such as energy con-sumption reducing lighting or optimaloperational management and energycontrolling systems.

Operating ConceptThe operating concept defines the qualitycontrol measures for the architecturaland HVAC concept as well as the subse-quent operational management. Carefullycalculated benchmark data derived fromthe operating, financing and energy con-cept allow builders to take the first criticalstep in the planning process:

Architecture and DesignBased on the general data on usage re-quirements, the energy, financing andoperating concept, the location and to-pography of the potential constructionsite have to be examined at the beginningof the architectural planning process.

In terms of the structural direction of thebuilding and the resulting facade design,the builder has a variety of options to in-fluence same to optimize the building’sfuture energy consumption. The facade,which usually also has to meet represen-tation expectations should absolutely bebuilt in such a manner that it does notoverheat in the summer, especially giventhe restrictions of the EnEV regarding themaximum solar influx value. The follo-wing principle applies: the setting eve-ning sun at the western facade requiresefficient external shading from the sunand a minimized facade opening.

Materials and Building SuppliesThe architectural design of the buildingdictates the requirements in terms of in-sulation, which must be compared withthe reference building defined pursuantto EnEV. The storage capacity and thesolar influx via the facades must be se-lected in such a manner that any over-heating during the summer months canbe ruled out.

Technologies The final phase deals with issues of heatand cold energy conversion, ventilationsystems and application systems such aslighting, EDP equipment and other uses.

In congruence with the procedure of theplanning process, measures stipulated inthe energy concept are now being imple-mented: the sum total of technologies,architecture and building materials gua-rantees that a sustainable office buildingwill be built.

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According to the EnEV 2007 a referencebuilding with similar geometry, orienta-tion, net floor space and use will have tobe depicted for each building to calculatethe primary energy demand. The energydemand of the planned building or buil-ding parts must not exceed that of thereference building.

Cooling energy demand will require spe-cial attention. The energy required forcooling cannot be applied to the refe-rence building. This means that the requi-red energy for cooling of the newbuilding must be saved on heatingenergy; which can, for instance, be achie-ved through particularly efficient insula-tion or energy provision.

Renewable energies improve the primaryenergy demand of an office building,their use must be verified.

The requirements of the building enve-lope are defined in the EnEV 2007 withthe thermal coefficient of transmission.The efficient prevention of summeroverheating is claimed by compliancewith the maximal solar energy influxvalue pursuant to DIN 4108-2:2003-07article 8.

Legal Requirements for Office Buildings - EnEV: German Energy Savings Act

Other cooling relevant requirements arethe energetic inspections of air-conditio-ners and the obligation to install new de-vices with automatic control system.

The EnEV 2007 meets demands of energyefficiency in buildings. The type of con-struction does not impose any specialtechnical requirements and can be wellresolved from both, the technical, as wellas the architectural point of view. The re-quirements imposed on the referencebuildings for hot water supply, solarequipment, BTU technology and optimi-zed distribution reflect the current tech-nically economic state-of-the-art.

The DIN V 18599 is based on the EnEVand a highly effective tool, which prescri-bes precisely the calculation methodsbased on the form of utilization.

An amendment of the current Energy Sa-vings Act is planned for 2009. With theEnEV 2009 the requirements of the maxi-mal primary energy demand, the thermalcoefficient and the maximal solar energyinflux value will be further tightened. Fur-thermore, minimum requirements for in-sulation of cold water tubes and fittingsfor cooling supply are discussed to be

Requirements for Building Components

Component Recommended thermal conductivity values for office buildings [W/m²K]

Walls facing exterior air 0,20

Walls facing unheated or undeveloped roof areas 0,20

Walls facing other buildings on land or construction site boundaries 0,20

Soil contact walls and floors 0,25

Windows, doors with windows and vertical transparent components facing exterior air, exterior doors 1,00

Ceilings facing exterior air, facing roof areas (with air flowing through or not insulated) and across drive through areas as well as inclined roof areas facing exterior air 0,15

Interior ceilings facing unheated parts of the building 0,25

prescribed. As well heat recovery from airconditioners and central ventilation ap-pliances that at least meet the classifica-tion H3 pursuant DIN EN 13 053:2007-09are discussed to be compulsory.

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Building Type and Amenity Standards

Building and amenity types are divided into three categories:

1. Administrative buildings with standard amenities > lowest investment costs and target compliance with statutory

elementary conditions

2. Administrative buildings with optimized amenities > best investment cost/operating cost, utilization quality and

value retention ratio

3. Administrative buildings with luxury amenities > maximum conveniences, representative building and use of

highly efficient technologies

tion concept and taking into account the fu-ture operating costs. Administrative buildingswith standard amenities and specific costs ofEUR 1,200 per square meter can comply withthe current statutory requirements if archi-tecture, building materials and technologiesare utilized in an optimized fashion. Thesebuildings are efficiently heated and usually donot require cooling.

Optimally equipped administrative buildingsusually call for investments per square meterthat are EUR 200 to 400 higher. The applica-ble utilization and efficiency class that appliesto these buildings is quite different. Thesebuilding types can already come in below thecurrent legal maximum values. The structuresprovide high utilization quality, can be ope-rated in an economically optimized fashionand retain their values sustainably.A luxury representative administrative buil-ding requires investments of EUR 1,600 to3,000 per square meter and is equipped withinnovative, intelligent technology that attainsexcellent cost-benefit ratios thanks to its mo-dern systems.

The principal rule that applies here is obvio-usly that energy efficient administrative buil-dings with optimized interior performance donot only generate low investment costs, butthat they also offer savings potentials of 30 to40 percent in a comparison with the opera-ting costs of a fully equipped building withventilation system, humidification and de-humidifier and outside temperature indepen-dent air conditioning.

Modern administration buildings and officebuildings have to fulfill numerous tasks. Theyprovide job sites for employees who have tohandle a variety of functional assignmentsand also represent the company.

The fundamentals for the next work steps inthe planning process and the architecturaldesign emerge from the definition of the buil-ding type based on the financing and utiliza-

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After an average of just 12 years, the operating costs for heating and coo-

ling frequently outpace the investment costs for technical

equipment such as heating and cooling systems.

Buildings are long term investments. Planningdecisions do have far reaching effects and er-roneous decisions can frequently only be cor-rected at a substantial expense. Conveniences,utilization capabilities and operating costs de-termine the sustainable ability to lease thebuilding and also its future sales value.

Scientific projections indicate that

> the number of summer days per year with temperatures reaching more than 25 degrees Celsius will double

> the number of high heat index days per year with temperatures reaching more than 30 degrees Celsius will quadruple

> the number of frost days per year will see a drop of 50 percent

Building Type and Amenity Standards

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Lower operating costs -protect the environment

Control factor Main floor space operating costs

Electricity/cooling 15 - 40 EUR / m²aCleaning 15 - 35 EUR / m²aInspection and maintenance 5 - 35 EUR / m²aValue retention maintenance 5 - 15 EUR / m²aHeating 5 - 15 EUR / m²a

source: Leitfaden Nachhaltiges Bauen, Dt. BM für Verkehr, Bau und Wohnungswesen

140%

120%

100%

80%

60%

10 15 20 25 30 35temperature °C, sedentary work, light clothing

10 15 20 25 30temperature °C, light work, light clothing

Human performance capacity is contingent upon room climate

satisfaction

accidents

intellectual activity

cyclesleight of hand

Utilization requirements Office buildings must be designed in such away that they provide their users with opti-mum conditions for creative and productivework environments. Deficits in building qua-lity translate into declining performance, he-alth impediments and ultimately a reductionin the level of motivation exuded by highlyqualified staff members.

The climate is changing Recently published studies and projectionsagree: the average temperate will rise by 2 or3 degrees Celsius over the next two decades.This makes it evident that we will be facing anew challenge imposed by the climate as well,in particular in regard to the appropriatenessof buildings for occupation during the sum-mer months.

Room Temperature and Economy If the room temperature is increased by amere 4 degrees Celsius, the ability to concen-trate and consequently the productivity of anemployee is reduced by 15 to 20 percent!

In buildings, where the interior temperaturesduring the summer months are significantlyhigher than the exterior temperatures, thiscan translate into a loss in productivity equa-ling 37 hours per year and per employee. In abuilding occupied by 100 employees who costan average of EUR 70 per hour and head, thisresults in a loss of EUR 259,000 per annumfor a business.

Moreover, a further increase of energy costs isalready foreseeable. At the beginning of 2008,the oil price per barrel first crossed the EUR100 threshold and pertinent discussions al-ready consider the crossing of the EUR 200threshold a possibility; the only question re-maining is actually at what point in time thisprice level will be reached.

Investments instead of energy costs A new building that can be heated at the rateof 15 kWh/m2 and year only utilizes about afifth of the energy of an existing building.Moreover, in combination with the utilizationof renewable energy, it can be optimized to alevel where future oil and gas price develop-ments no longer have to cause headaches. Inother words, the strategy for success appliedto the planning processes of modern and eco-nomically sustainable office buildings canonly be the following:

Sustainability: CO2-optimizationIt is already evident that the management ofCO2-emissions costs will be the key controltool in the European region. Even today, theaversion of CO2-emissions can be measuredin tons and therefore monetary value. InEurope, the current value allocated to eachton of CO2 ranges between EUR 15 and 25.

Sustainability thanks to energy efficiency A new administrative building consumesenergy when it is:

> heated and cooled, > consumes lighting, > hot water, > requires ventilation and > operates devices.

The actual energy consumption is determinedby the quality of the building envelope, thetechnical amenities of the building and thebehavior of its users.

Heating still makes up the largest portion ofthe overall energy balance sheet. However,given the foreseeable trend toward increasingexterior temperatures during the summermonths, it is safe to assume that the portionof energy consumption dedicated to coolingwill increase significantly.

The new building code requirements gover-ning the heating and cooling requirements tobe met by newly erected non-residential buil-dings call for a limitation of the heating de-mand to 10 to 27 kWh/m2a (depending onhow compact the building is).

Deciding factors for the financing concept driven by economized climate protectionThe taking into account of the described eco-nomic standards results in new factors relatedto the financing concept of a new building,which, along with the reduced energy costsand the high utilization and resale valueof the building, provides completely newdecision-making criteria.

invest into energy efficiency today instead into energy

costs tomorrow.

Building Type and Amenity Standards

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> Reduce interior sources (to 300 W per person)

The costs for the performance of a dyna-mic building simulation range from EUR3,000 to 5,000 for a building comprising1,000 to 2,000 m².

Materials and building suppliesThe statutory minimum thermal conduc-tivity values are critical for the selectionof the appropriate building materials. Asecond aspect, which also has to be takeninto account, is the thermal insulationthe individual materials provide. It is ne-cessary to give buildings storage capacityand mass to reduce or completely ruleout summer overheating.

In addition to a choice of building mate-rials with high density and high storagecapacities, such as concrete, brick andloam, the market today also offers mo-dern and innovative building materialssuch as phase change materials that op-timize the storage mass through thephase transition provided by small waxparticles and stucco cardboard.

Besides architecture, materials and buil-ding supplies are also contingent uponthe building design. Quality managementmust be integrated into the constructionprocess from the very beginning. All com-panies involved have to be aware of thefact that construction surveillance isbeing performed under energy efficiencyaspects.

Air tightness tests for buildings One of the highly effective quality moni-toring tools prior to the final acceptanceand in compliance with building code re-quirements is the testing of the construc-tion’s air tightness. Pursuant to buildingcode requirements, the building’s enve-

Architecture and Design

Based on the earlier described controlfactors > Target temperature and humidity levels> Air quality and ventilation > Building materials and resulting

storage mass > Optimization of interior performance in the energy concept and choice of buil-ding and amenity type, architecture anddesign do have a huge impact on theenergy balance sheet of a building.

The location and topography determinethe direction of the building and the fa-cade design. Construction that is optimi-zed for solar energy use prevent summerheat loads and take advantage of wintertime energy influx generated by solar ra-diation.

During this phase of the planning process,proposals and requirements can be sub-mitted to the planning team as well. Adynamic building simulation, for instance,provides critical decision-making funda-mentals. Every change made in terms ofinsulation, ventilation, glass use, usageand utilization of devices has an impacton the investment and operating coststhat can be mathematically calculated.Within the scope of a dynamic buildingsituation, which takes into account nu-merous factors, it is possible to calculatethe future energy requirements of a buil-ding as well as the consequences of po-tential overheating days during summer.This makes it possible to optimally assessthe utilization quality.

The following fundamentals apply: > The insulation standard must be

maximized > The ventilation must be optimized

(perform 0.5 to 1.5 air exchanges per hour and room)

> Optimize shading > Optimize the use of daylight > Optimize interior temperature and

humidity levels

lope is checked for air tightness prior tothe final acceptance inspection. The buil-ding is qualified by way of a so-called nL50-value. During the inspection, the buil-ding is subjected to over and under pres-sure. In a building with a mechanicalventilation system, the air exchange mustnot exceed a maximum value of 1.5/hunder a pressure level of 50 pa.

TechnologiesOnce the target values have been definedin the architectural concept and the ma-terials as well as the building supplieshave been selected, the next decision tobe made pertains to the technology to beused. The following rule applies:

The first priority is to optimize the buil-ding in such a manner that it requires aslittle heating and cooling as possible. Onlyat this point does the utilization of inno-vative technologies to cover the energyneeds become a critical topic. Amongother things, this means > Optimization of interior sources

such as PCs, printers and servers> Target value for interior performance

is a maximum of 300 W per person> Optimization of lighting

(daylight dependent controls and efficient technology)

> Optimization of solar influx into a building through external sun shades

> Optimization of ventilation patterns (0.5 to 1.5 air exchanges per hour)

Depending on the type of amenities andlocation of the building, builders have attheir disposal a variety of heating andcooling technologies to be decided uponduring the planning process; pertinentbuilding code requirements apply.

The Energy Certificate as a quality featureAccording to building code requirements,the Energy Certificate for non-residentialbuildings documents the efficiency classthe building has been allocated to. In thelong term, it will have a critical impact onthe ability to lease and retain the value ofthe building. The Energy Certificate > is an energy rating label for a building> establishes a seal of approval for the

energy quality of buildings> shows the energy consumption and

energy efficiency of buildings> ensures transparency, comparability

and competition for planners, builders, owners, landlords, prospective buyers and tenants.

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Conserving energy (i.e. the energyefficiency of the building’s

envelope) is more important than efficient production.

Storage mass optimization ensuresthermal insulation (1,500 kg/m³).

Architecture and Design

The effects of solar radiationA simulation model, such as the one de-picted on the right, is used to test the in-terior effects of solar radiation on theroom, which is particularly important forwork spaces. It makes it relatively easy toplan with foresight.

Dependence of indoor climate oninfluential factors direction andpercentage of glass cover

Shows the maximum temperatures inoffices if exterior temperatures reach32°C – windows with exterior sun sha-

ding, window ventilation (crevice ope-ned at night), median occupation den-sity:

Direction of window front

east - south

south - west

southeast - southwest

northwest - northeast

Percentage of window areas30% 50% 70%

31,8°C 34,3°C 36,8°C

31,8°C 34,4°C 36,9°C

31,7°C 34,3°C 37,6°C

29,7°C 31,2°C 32,8°C

Daily progress in a south-west facingcorner office

Temperature curve over a 24-hour periodThe graphic shows how the room tempe-rature changes within a time frame of 24hours in an interior room – in relation tothe window covered portion of the buil-ding’s facade.

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Project Braun AG, Kronberg

Architects: Schneider+Schumacher, Fft.a.M.Project participants: Stefano Turi, Fft.; Th.Zürcher, D. Wagner, B. Heiner, T.Schult, K. D.Sievers, N. Alexopoulos (associates); Hoch-tief AG, Frankfurt (general contr.); Ove Arup,Berlin (grider planing); Magnus MüllerGmbH, Butzbach (facade construction);WICONA Bausysteme GmbH, Ulm (facade) Principal builder: Braun GmbH, Kronberg Location: Frankfurter Str.145, Kronbg. i. Ts.

Structural descriptionThe competitive tender called for the newbuilding to be erected on the parking lotterrain. The architects converted these in-structions and chose the site for the newconstruction right next to the drivewayentrance of the company premises. Theshape of the building is extremely basic: athree-floor U-shape provides the footprint.The interior courtyard is vast and coveredand has a slightly shorter shank creatingthe entrance scenario in combination withthe roofing. A ramp takes visitors into thecentral three-floor foyer, which is coveredwith air cushion pads. This buffer zone bet-ween interior and exterior space does notonly play a major role in the climatizationconcept, but also offers room to linger. Itprovides access to the building and spacefor exhibits and events.

The steel concrete construction has aw-ning-like ceilings to create a room wit-hout support beams. It is ideal for avariety of office concepts and divisions.Cubicle-style, combination and openfloor office plans are possible. The supplyinfrastructure (power, etc.) is providedthrough a double floor; basic lighting isintegrated into the ceiling.

Energy concept/insulationThe fundamentals of the climatizationconcept were developed during the con-ceptional competition in partnership withengineering firm Ove Arup and were sub-sequently optimized. The concept calls forthe tempering of the rooms to be achie-ved entirely through the ceiling surface.The heating/cooling ceiling consists ofcapillary tubes integrated into the stucco,which allows it to activate its storage

mass. The atrium provides the buffer zoneand allows solar gains in the spring and inthe fall. During the summer months, it isconverted into an exterior room via "pil-lows" that can be opened. In the winterit is heated to an intermediate tempera-ture by the heat radiated by the officesections. The room is ventilated by naturalthermal convection. Earth channels tem-per the incoming fresh air. The facade,which can be individually controlled, al-lows the natural influx of fresh air andthe suctioning off of exhaust air from theoffices. Only the interior zone is mechani-cally ventilated by a source ventilation sy-stem via outlets on the floor.

In combination with the long water basin,an earth storage device improves the airquality in the central foyer considerably.The exterior facade comprises floor highinsulation glass paneling that can be ope-ned and has been installed as a dualformwork exterior facade. From an eco-logical standpoint, glass is indeed a buil-ding material that makes sense, giventhat the production energy expended en-sures a highly favorable ratio in compari-son to its longevity. Sun shading andshielding against blinding is provided byVenetian blinds, which are installed onthe interior for protection. The openingof the facade rules out any overheatingduring the summer. The ceilings have beenfitted with thermal insulation panels. Dueto the lack of solar radiation, parts of thenorth facing facade are heat insulated.

Energon, Ulm

Principal builder: Software AG Stiftung, Darmstadt

Ventilation concept - A deciding factorfor the sustainable operation of the buil-ding is its ventilation system for fresh airand exhaust air. The ventilation conceptin this case is convincing thanks to its in-telligence and simplicity. Fresh exterior airis suctioned in by a wide, 28 m long con-crete pipe. The surrounding soil warms orcools the air depending on the season.The air is subsequently filtered, additio-

nally cooled or heated; and if necessaryhumidified before it is channeled into theinterior covered atrium, which serves asthe fresh air diffuser for the office andbreak rooms.

Climatization - An intelligent climatecontrol system with concrete core tem-pering ensures that the room climate isconsistent and comfortable throughoutthe seasons. A total of 350 plastic tuberegistered have been installed into theconcrete ceilings of each floor. Warm orcold water stream through these registersand deliver the same effect a large sur-face heating or cooling system wouldprovide. The concrete ceilings store thetemperatures and ensure consistent cli-matization with only minor temperaturevariations. Additional cooling is providedby 40 earth warmth probes buried allaround the building, which reach depthsof 100 m. The soil, which is always 10 de-grees cooler than the ambient air tempe-rature, absorbs excess heat from thebuilding and stores it to reuse it if neededto preheat the cold fresh ventilation air. Itgoes without saying that this extremelyefficient energy storage system alsoworks vice versa and assists with the coo-ling of the building.

Optimum percentage of glass coveredsurfaces - If a building cools off inside oroverheats, complex and costly measureshave to be taken to compensate for thesefluctuations. Consequently, the glass co-vered areas of the Energon facade totalan optimum 44 percent. The buildingdoes not require protruded segments andviews are therefore unobstructed. Thebuilding is shielded from excessive solarradiation by mechanically operated exte-rior light control blinds that can be indi-vidually controlled.

Effective insulation - The innovativebuilding located in Ulm‘s Science Park II isbased on a passive solar structure concept.The steel concrete skeleton constructionboasts an airtight building exterior madefrom highly heat insulated wood elementsand a mechanical ventilation system withwaste heat recovery. The Energon buildingwalls and covers are insulated with virtu-ally no heat bridges: 35 cm insulationthickness in the facade, 20 cm below thebuilding foundation and up to 50 cm onthe roof. Modern triple pane window per-fects the concepts.

Electricity utilization concept - An in-telligent lighting system makes substan-tial contributions to electrical energyconservation. The Energon structure also

Examples > Best Practice

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boasts a 328 m2 photovoltaic system in-stalled on the roof outside the atriumroof. This translates into the self-produc-tion of 12,000 kWh electrical energy.

Electronic control - A highly innovativebuilding automation system monitorsand controls the various systems thatsupply the building infrastructure. Tem-perature and air quality in the atrium arecontinuously measured and optimizedthrough the controls of the fresh air fanand the ventilation flaps. The waste heatrecovery is controlled in compliance withtarget values and depends on the freshair and exhaust air temperatures.

Lighting concept - The building boastsan optimized concept for daylight and ar-tificial lighting as well as an electricityconservation concept for lighting and de-vices in the building. The percentage ofglass surfaces of the exterior facade hasbeen optimized in terms of heat andlighting requirements. Sun shading isprovided on an as needed basis by lightcontrolled exterior blinds in front of theoffice windows and by semi-transparentfoil blinds integrated into the roof of theatrium.

Special features - Other special featuresof the building include the roof coveringmaterial consisting of flexible photovol-taic foil, the harmonious color conceptand the ecologically designed landsca-ping. This extraordinary structure has re-cently been certified as an exemplarypassive solar house. Building parameters in reference to thenet floor space > Heating energy req. max. 15 kWh/m2a> Electrical energy required for building

technology approx. 5 kWh/m2a > Primary energy dem. app. 68 kWh/m2a> Operating costs approx. 2,9 EUR/m2a> Building costs 1.400 EUR/m2

Office BuildingDeutsche Bahn AG, Hamm

Location: Hamm, Westfalen Investments, subsidies: 1.130 EUR/m²NGF (KG 300 a. 400); 628.275 EUR Subsidies provided by BMWA (SolarBau)

Project descriptionThe principal builder of the DeutscheBahn AG office building in Hamm is aninvestor. The compact structure of the U-shaped building encompasses an atriumopening to the east from the first to thefourth floor. The ground floor below theatrium receives its lighting through sky-lights and is thermally separated from theair space located above it. The air space isa buffer zone that is not to be heated. Themain entrance is located in the east onthe glass encased side of the atrium.

The floor plan of the building is dividedinto various functional areas: the insertedsectional spaces (houses inside of ahouse) are located in the west, along withancillary space and infrastructure. Thesouthern and northern sections of thehouse are used as office space in a varietyof ways. The ground floor houses serviceareas and additional offices. The newconstruction has a basement only in thewest. It accommodates warehouse andtechnical rooms. The five floors comprisea total net floor space of close to 6,000m².

The central focus of planning was on alargely naturally ventilated and lightedoffice building without active regular of-fice climatization. A specifically alignedbuilding design and the interaction of ef-fective sun shading, fair faced concreteceiling providing storage mass, night timeventilation and a 1.8 km long air/soil re-gister counter act summer time overhea-ting. The atrium is a critical componentof the ventilation concept. The architec-tural plans were the result of a tendercompetition. The architects collaboratedwith energy planners at Karlsruhe Univer-sity from the start. The role of the princi-pal builder during the planning phasewas assumed by the future user.

Building data thermal insulation:Thermal conductivity value (roof) = 0.23W/m²K Thermal conductivity value (floor) = 0.52W/m²K Median thermal conductivity value (en-tire building) = 0.57 W/m²K

Costs and efficiencyThe constructions costs for the officebuilding totaled 1,130 EUR/m², in refe-rence to the net floor space (cost esti-mate pursuant to DIN 277, KG 300 and400). Of these - building construction (KG 300) made up777 EUR/m² - technical equipment (KG 400) made up353 EUR/m².

A subsidiary of EUR 628,275 was awardedfor the expanded planning and the moni-toring of the administrative building bythe German Federal Minister of Economyand Labor (Bundesministerium für Wirt-schaft und Arbeit; BMWA) within thescope of its support program SolarBau.

Paul-Schnitker-House, Münster

Kresing Architects, MünsterProject participants: Büro Brandhorst, Bonn (structural phy-sics); Morhenne+Partner GbR, Wuppertal(TGA); Fraunhofer Institut für Bauphysik,Stuttgart/Holzkirchen (measuring tech-nology/building physics); Dr. Löfflad, Köln(structural ecology)Principal builder: HWK Münster (Chamberof Crafts Trades); Office completion: 2004Location: Franz-Meis-Str. 2, Münster

The Demonstrationszentrum Bau undEnergie (Demonstration Center Construc-tion and Energy) is designed as a compre-hensive model for integral buildingplanning. The building complex consistsof two structures: a two-story duplex,which combines work space and resi-dential space and a large building com-prising a multi-sectional house and afoyer of 150 m2.

The forum building is a four floor glassfoyer with a diagonal wood frame. Ithouses the consulting and exhibition spa-ces. In addition to a reading counter onsustainable building, it provides a mate-rial library examining the entire spectrumof sustainable construction materials.

Just like the building technology, the hea-ting and cooling systems comprise a widespectrum of innovative options: from thewood pellets heating system to a heatpump, an efficient waste heat recoverysystem to solar cooling to an absorptioncooling system. The HVAC data is recor-ded across 500 measuring points andpartially made accessible to visitors on-line. As a result, the exhibition objects areeffectively complemented by measuringdata and analyses.

Examples > Best Practice

11

Insulation Two building components were added tothe glass encased forum as additional ex-hibits. They were implemented in diffe-rent construction and energy standards.The three-section house complex rightnext to the forum comprises a low energyhouse and lime sand stone walls and cel-lulose insulation behind a back ventilatedwood facade and a passive solar house,as well as a minimal energy house inwood frame construction with various re-newable insulation materials. Unlike thepassive solar house, the minimal energyhouse is largely solar heated.

The second free-standing building com-plex comprises a duplex built from porousadobe and pumice in different styles ofmassive construction. The pumice sectionwas realized with a thermal insulationcombination system using lime sandstone with mineral foam insulation andthe adobe with wood fiber insulation pa-nels.

The different construction styles are evi-dent on the facade of the duplex. Addi-tional different styles of construction,wall and ceiling structures have been im-plemented on the interior of the buil-dings for demonstration purposes.

Users describe the comfort level withinthe buildings as excellent.

BOB, Aachen

Architects: Architekturbüro Hahn Helten, AachenProject participants: VIKA Ingenieur GmbH,Aachen (energy concept, technical buil-ding equipment); Ingenieurbüro für Bau-wesen Burkhard Walter, Aachen (frameplanning); enervision GmbH, Aachen (buil-ding control and communication system)Principal builder: builders‘ association,among others VIKA Ingenieur GmbH, Aa-chen Completion: 2002

Energy conceptOne of the key features of the BOB is itsenergy concept. With its very minimalenergy needs, the building is one of Ger-many’s 25 most energy efficient officebuildings and is therefore receiving subsi-dies from the federal support program"SolarBau".

The heating energy requirements ofBOB.1 with a total floor space of 2,100 m²is the equivalent of that of a standardsingle family home. This low level ofenergy consumption is attained thanks toa concept combining a compact buildingwith high level thermal insulation and thegeneration of the heating and coolingenergy required from geothermal sources.

Moreover, day light controlled lightingsystems were complemented with a buil-ding control and communication system,rain water catchment, concrete core tem-pering as well as a fresh air and exhaustair system with waste heat recovery. Atotal of 28 soil drill holes were completedat depths of up to 45 m. During the win-ter, the geothermal heat is increased tothe required temperature level by adownstream heat pump. During the sum-mer, the geothermal cooling energy canbe obtained straight from the soil. The in-stallation of a costly and energy intensiveair conditioning system was therefore notnecessary. Electrical power is only requi-red for the water pump drives and the re-volving pumps, which are required in anyevent.

Based on a total electrical energy con-sumption of 19 MWh per annum, thegeothermal system provides 133 MWh tooperate the building. Concrete core tem-pering is used to heat the building. It isbased on the principle of surface heating,which makes operation at minimaluploading temperatures possible andconsequently allows the best possible uti-lization of geothermal heat. As a result,the temperatures inside the building re-main virtually unchanged. The fluctuati-ons between summer and winter reach amaximum of 2° Celsius (median valuebased on 2003) while the outside tempe-ratures may fluctuate by up to 20° Cel-sius. Thanks to this optimum balancebetween hot and cold temperatures, themonthly energy costs of building BOB.1total only 0.22 EUR/m² floor space. Inconventional buildings, the energy costsincurred range from 0.50 to 2.00 EUR. Theenergy required for heating, cooling, ven-tilation and lighting totals 25 kWh/m²a.

Solar constructionSolar construction is part of the energyconcept described above. The building isfacing north/south, access is provided onthe north end. An open, flexible floor planlayout warrants the optimum use of daylight.

Thanks to the optimization of windowsizes and glass quality, no exterior sunshading is required; all that is needed isinterior shielding from blinding light. Thesolar heating and cooling energy is indi-rectly activated by the energy stored inthe soil, which is generated by earth pro-bes.

Electrical planning/HVACA building control and communicationsystem ensures intelligent controls. Acentral PC controls all switches, ventila-tion devices, heating and cooling techno-logy and lighting via BUS cables. Theartificial lighting is dimmed automati-cally. Day light controlled blinds ensurenon-blinding lighting of the rooms du-ring the summer season.

The BUS technology allows changes inswitch control at any time, and also themodification of timer settings, etc., whichcan be easily reprogrammed on the cen-tral computer. New wiring is not required.The modular technical structure also al-lows the reconfiguration of offices (indi-vidual, double, group, combined or openspace offices) without any new installa-tion. This flexibility is further supportedby the clear horizontal and vertical distri-bution of the technology, thanks to thefact that technical installations on the in-terior walls do not exist.

The building control and communicationsystem is connected to the Internet. TheBOB developers offer their building usersa complimentary energy check each year.Moreover, the owners of the buildinghave the option to check the equipmenttechnology from their homes. They canalso turn off the lights and control thetemperature in the same fashion.

Examples > Best Practice

12

> Solar Energy > Concrete Core Activating > ‘Green IT’

Solar energySolar energy is the earth’s largest usableenergy resource. It enters the earth atmo-sphere in the form of radiation and holdsabout 1,360 W/m² of power. As it travelsthrough the atmosphere, solar energy isreduced through the absorption streamsand reflection; the actual radiation thathits the earth still totals about 1,000W/m². The global radiation fluctuates de-pending on season, elevation and radia-tion angle.

Solar energy can also be integrated intothe planning process for energy efficientoffice buildings. Passive solar utilizationis achieved through structural measuresthat take advantage of solar energy forheat production during the winter seasonand for the production of room lighting.Active solar energy utilization is securedeither through solar-thermal usage orthrough photovoltaic systems.

Solar thermal systems for heating and cooling The use of solar energy in solar thermalsystems is technically mature and astandard solution for the preparation ofhot water in private households. Even inadministrative/office applications, solarthermal equipment is an ideal solutionfor the production of highly efficienthot water supply systems, which can beutilized if the building requires > hot water for showers> hot water for kitchen> hot water for cleaning purpose

The integration of solar thermal equip-ment into a building’s heating system isalways expedient if low temperature sy-stems have been installed in a building.This approach allows the feeding of floorheating, wall heating and concrete coreactivation systems with solar energy du-ring the transitionary.

Innovative options, such as solar cooling,are also available. In combination with anabsorption cooling system, administrativebuildings can be cooled with solar energy,which is converted into cooling energy bythe absorber and transported into the of-fice spaces via surface cooling devicessuch as capillary cooling and concretecore activation.

Photovoltaic systemsPhotovoltaic systems allow the directconversion of solar energy into electricalenergy. The largest yield is attained if thebuilding is south facing and sits at an in-cline of approximately 30°. However, de-viations toward the SE / SW (45°) onlyreduce the yield by 5-10 percent. Facadeintegrated systems do not only generateenergy, can also be used as design ele-ments and emphasize the environmentalawareness of the company. The invest-ment costs for small systems (1-3 kWp)range from about EUR 4,500 to 5,000 perkWp; the specific costs drop dramaticallyas the size of the system increases. At thistime, government subsidies for PV areavailable in the form of an increasedfeed-in rate.

Concrete core activationConcrete core activation requires the in-stallation of water transporting tubesinto the concrete construction (usuallyinto ceilings). This option allows the pro-vision of heating and cooling energy ateconomically reasonable costs. Thanks tothe large storage mass, energy is usedvery effectively during low temperatureoperation; and the heating and cooling isvery comfortable from a physiologicalpoint of view. This system does not re-quire maintenance.

Concrete core activation offers limitedcontrollability, i.e. users have no option todirectly control or set the temperature.When the work day begins in the morning,the components are cooled down to 20°Cand as the day progresses during the sum-mer months the temperatures rise slowlyand can reach up to 26° or 27°C. If an em-ployee feels too cold, a window can beopened to increase the temperature; ho-wever, it is not possible to spontaneouslydecrease the temperature.

The room is experienced as an agreeablycool place, but one does not get the im-pression that it is being refrigerated. If thesystem is set up optimally, the tempera-ture perception meets the human needfor comfort. Throughout the entire sum-mer, the room acts like a thick walled andthermally indolent old building at thestart of a period of hot weather.

Concrete core activation is contingentupon the availability of unrestricted heator cold air radiation into the room. Con-sequently, it cannot be used in con-junction with lowered ceilings. This maylead to acoustic problems in the interior

room, for which compensation measuresmust be considered in the planning pro-cess.

Concrete core activations work as freecooling systems very well during transi-tionary periods. To this end, the coolingenergy generated from a probe, a flat col-lector or well and cold water (10 or 12degrees) is directly fed into the concretecore activation; no heat pump is required.As a result, this solution can producecomfortable room temperatures for 3 to 5months out of the year without a coolingmachine having to be operated. The soleexpense stems from the operation of thehydraulic pumps that pump the waterinto the ground and cause it to streamthrough the concrete core activation inthe ceiling.

Green ITThe integration of innovative informationtechnology into modern administrativebuildings is of critical importance forbusinesses. Under the heading Green IT,topics such as the electricity consump-tion of computers at work stations and ofservers, are now frequently discussed hotissues. New ground breaking technologiesare emerging all the time.

Server rooms once occupied by individualservers and storage disks will soon househighly efficient devices that require not-hing but a single rack to provide the ser-ver performance needed for 100 to 200work stations. One of the key componentsdriving this trend is the improved com-puter capacity utilization by virtual ser-vers.

Natural cooling in server roomsOptimized server rooms boasting coolingcapacities of 5 to 7 kW are now common-place thanks to water cooled racks thatcan be recooled by earth probes. Bothsides of the rack have water cooled surfa-ces as well as a fresh air/exhaust air sy-stem that cools the electronicinstallations. The cooling water tempera-ture of 18°C combined with cooling ca-pacities of 8 kW and an earth probewarrant adequate server room cooling indirect operation. Depending on the priceof the probes used, the investment intosuch solutions can be amortized within 3to 5 years; while the operating and main-tenance costs as well as the failure secu-rity of the system deliver clear argumentsin favor of the state-of-the-art develop-ment trend towards natural server coo-ling.

13

Influential Factors Controlling the Energy Needs

Direction of the buildingThe attainment of compliance with thestatutory target requirements and the bestpossible classification in the Energy Certi-ficate is influenced by various factors, in-cluding the direction into which thebuilding is facing. Building sites or deve-lopments cannot always be randomly de-signed and it is not always possible to alignthe building with energy efficient aspects.However, it is always possible to optimizethe set-up through the sequencing ofrooms, offices, and meeting rooms.

From an energy technical point of view,north-facing windows are ideal for officebuildings. The daylight is largely non-blin-ding and it is far less likely that the roomswill be overheated in the summer than itwould be in rooms facing east or west.South-facing rooms do not pose anymajor problems either, since the sun isusually sitting at its zenith by noon andtherefore the rays do not reach into theserooms. East and west-facing rooms aremuch more complex. They require externalsun shades, especially, when the sun is set-ting, to avert overheating.

To optimize the protection from the sunwhile taking advantage of the day light,the direction and design of the buildingtherefore calls for different facade structu-res depending on the direction they are fa-cing.

Energy efficient and storage mass optimi-zed buildings with optimum daylight uti-lization and simultaneous sun protectionhave larger north-facing windows than

south-facing windows. Pointing east andwest, they have optimized minimalwindow areas with external sun shades,which ensure that they fulfill all of theaspects an energy efficient building mustmeet.

Sun shades are essential componentsfor modern office buildingsIf external sun shades are used on allsides of the building, the direction the of-fice is facing is no longer a critical aspect.The differences in energy consumptiontotal less than 2 percent if a dual tract of-fice building is rated at a rate of 90 per-cent. Sun shading systems are divided intotwo categories: > passive fixed sun shades > active mobile sun shadesFixed overhangs, cantilevers and shieldsabove windows are used as passive sunshades. Given the radiation angle, thesemeasures are only effective on south-fa-cing facades, while they do not comple-tely prevent radiation from entering therooms on the other sides of the building.All they do on the other facades is redu-cing the influx of daylight.

Active sun shading systems can be loca-ted in front of the facade, in betweenwindow panes or on the interior. Howe-ver, it is important to remember that onlysun shading systems installed on the ex-terior of the building do have an effectiveimpact on the energy balance sheet ofthe building. The shading efficiency of thesun protection system varies depending

on the bulge, adjustment angle and re-flection level of the slats.

Internal heat gain – a key aspectThe internal heat gain is a key aspect inregard to the summer climate to be anti-cipated. The more densely an office buil-ding will be occupied, the more difficult itwill be to do without a supporting coo-ling system.

Model calculations have shown that aminimum office space of 10 m² per em-ployee (based on standard building ame-nities) is the absolute minimum requiredfor an office to be operable during thehot summer months with night timewindow ventilation only.

6%

27%46%

13%

16%

17%

54% 14%

14%27%13%

5%48%86% Radiation balance sheet on the

window. Left: blind located on the interiorRight: blind located on the outsideSource: Handbuch der passiven Kühlung

x x

14

Human100 W

300 W

Lighting20-55 W

Printer15-20 W

Screen15-20 W

Fax Copier

Coffee mach.

Charger10-30 W

PC50-90 W

Influential Factors Controlling the Energy Needs

Source: BINE Themeninfo 1/05, Tageslichtnutzg. in Gebäuden, Fachinformationszentr. Karlsruhe, Bonn

kWh/m²a

500

400

300

200

100

0

lighting

cooling

heating

others

office buildingold, standard

office buildingnew, standard

office buildingnew, optimized

3%

23%

Significance of lighting regarding the primary energy demand of anexemplary office building

34%

18%

46%

31%

33%

30%

14%

23%

5%

40%

Night time window ventilation is basedon the following principle: throughoutthe day, the active storage masses of theroom are charged by interior sources andexternal heat gain. Overnight, the char-ged energy can be released into the roomand subsequently into the cooler night airthrough the air exchange occurringthrough the open window. As a result, theroom temperature in the office in themorning is comfortable enough for it tobe used and heats up again throughoutthe day.

However, if the storage masses are inade-quate or the internal heat sources are ex-cessive, or if the summer nights are toohot for any air cooling to take place, thebuilding heats up as the week progressesand by Wednesday or Thursday the usabi-lity of the rooms is already limited. Therooms’ interior temperatures are conse-quently substantially higher than thoseon the outside.

300 W per person maximum heat influxTo be able to operate a building with basicamenities that does not have air condi-tioning or a cooling system during thesummer months, the optimization of theinterior performance is an absolute ne-cessity.

Only if a value of 300 Watts per person isnot exceeded, will night time cooling suf-fice to release the influx energy back intothe outside air. This means that the inter-nal loads have to be optimized and prio-rity must be given to materials andbuilding supplies with high storage capa-cities.

Taking into account the heat radiated byhumans, which equals 80 to 100 Watts,an office equipped with a PC, a monitorand a charging device as well as 50 Wattslighting easily reaches the limit of 300Watts per person and therefore has to beoptimized already during the planning

15

> Efficient Lightning for Offices

row of lights 1 row of lights 2light sensor

light measuring

daylight

daylight and artificial light

> Plan the use of daylight, pay attention to providing non-blinding lighting and proper sun shading

> Use efficient lamps, lights and electronic ballasts, motions detectors and daylight sensors

> LENI recommended value for office buildings: 32.2 kWh/m² and year

Electronic ballast The obsolete versions of ballasts requiredfor ignition and power limitation still pro-duce performance losses of 13 W, whilemodern electronic ballasts attain valuesof 5 W lost performances and should ab-solutely be used in modern office buil-dings given their additional investmentcapital amortization of less than 1.5years.

Lighting management Automated lighting control is a keyfactor for an efficient overall systemalong with manual operation.

Such systems comprise: > Motion detectors> Daylight dependent controls with

light sensors and daylight control > Central lighting control through

integration of lighting into the building’s technical control system, automated switching, controlling, regulation or BUS systems

Key element: energy efficient lampsThe currently most efficient system avai-lable is the T5 fluorescent lamp (16 mmdiameter) which delivers a 25 – 45 per-cent greater light yield than the old T8standard

Key element: efficient lightsOptimum light reflectors and maximumpossible direct light percentage deter-mine the light operating effectiveness.The correct choice has a deciding impacton the overall energy required.

16

Type of lights lights operating efficiency

Lights with opal cover, old 50%Lights with prismatic cover, old 55%Lightswith prismen optics, new 77%Direct/indirect secondary reflector light, new 67%BAP light with high gloss parabolic mirror matrix, new 83%

Type of lamp heat light luminous efficacy durability (hours) (lumen/watts)

Standard bulb 95% 5% 8 - 15 ~ 1.000Halogen bulb 93% 7% 12 - 25 ~ 2.000IRC-halogen bulb 91% 9% 25 - 30 ~ 5.000Energy saving light bulb 75% 25% 38 - 66 ~ 6.000 - 12.000Standard fluorescent lamp 71% 29% 47 - 83 ~ over 8.000T5 fluorescent lamp 67% 33% 67 -104 ~ 16.000

> Efficient Office Machines

Format S/m* max. conspt. Sleep-Mode** Sleep-Mode* max. consumption in Off-Mode***Laser color | b-w Laser color | b-w (Stand by)

PrinterA3/A4 1 - 10 6 | 4 W < 30 | < 5 min 1 W

11 - 20 6 | 4 W < 60 | < 15 min 1 W21 - 30 6 | 5 W < 60 | < 30 min 1 W31 - 44 15 | 9 W < 60 | < 60 min 1 W

> 44 20 | 13 W < 60 | < 60 min 1 W

Multi-functional devicesA3/A4 1 - 10 14 W < 15 min 1 W

11 - 20 14 W < 30 min 1 W21 - 30 16 W < 60 min 2 W31 - 44 20 W < 60 min 2 W

> 44 24 W < 60 min 2 W

Fax 3 W < 5 min 2 W

Copy machinesA3/A4 1 - 20 14 W < 15 min 1 W

21 - 30 16 W < 15 min 1 W 31 - 44 20 W < 15 min 1 W

> 44 24 W < 15 min 1 W

* S/m = Quantum of DIN A4 pages per minute, one DIN A3 equals 2 DIN A4 print outs** Device in sleep mode

*** Device is switched off and has no function, but is not entirely cut from electricity

max. power consumption (Watt) On-Modus Sleep-Mod.* Off-Mod.**

Desktop PC Standard office application 50 3,0 2,0High performance application 90 3,0 2,0Monitors15/16 inch 23 2,0 1,017 inch 30 2,0 1,018/19 inch 35 2,0 1,020/21/22 inch 53 2,0 1,0NotebooksStandard office application 14 1,7 1,0High performance application 22 1,7 1,0

*Device in sleep mode** Device is switched off and has no function,

but is not entirely cut from electricity

Efficient office machines efficient officesInefficient office machines hit the cashregister twice: the increased power con-sumption has a negative impact on theoperating costs and their radiated heatcontributes to overheating in the summertime, which has to be compensated forthrough cooling and air conditioning,both of which consume large amounts ofenergy.

When purchasing office devices, energyefficiency should be a critical require-ment. The "Energy Star" label provideshelpful information. Criteria for PCs, prin-ters, copy machines, multi-functional de-vices, scanners and fax machines offerexcellent buying assistance. The EnergyStar database lists the models with thelowest energy consumption and theEnergy Star standard (www.eu-energys-tar.org).

Office devices consume most of theirpower not during actual operation, butwhen they are idle in ‘stand by’ mode. Thestand by portion makes up more than 90percent of the consumption in some mo-dels. Consequently, users should pay spe-cial attention to the electricityconsumption of office machines in va-rious modes of operation. When acqui-ring office machines, make sure theguideline values stipulated in the table interms of maximum rated power are notexceeded. It is recommended to includethese values into tenders for bids on of-fice devices.

17

Copier 30%Laser Printer 14%Monitor 12%PC 10%Others 10%Fax machine 9%Notebook 4%Flat screen 4%Scanner 4%Ink Jet printer 3%

Sleep Mode 46,0 kWh/aStand-by Mode 5,2 kWh/aNormal Mode 46,0 kWh/a

Share of single hardware at the electricity consumption in an average office

Share of operation conditions at the electricity consumption of any average scanner - total consumption 53,2 kWh/a

Integral Planning and Technical Design

Even if the planning is absolutely opti-mum, the building design and construc-tion cannot realize the desired interiorroom climate without the pertinent tech-nical equipment. Heating, lighting andpossibly also the cooling system have tobe aligned with the specific conditions ofthe building within the scope of an inte-gral energy concept.

HeatingEven if the walls and covers of the buil-ding are optimally insulated, it will stillrequire heating in the winter, which has asubstantial impact on the energy balancesheet of the building. The type of heat ge-neration also depends on the generalconditions at the location. In compliancewith building code requirements, the useof alternative energy systems such as > Energy systems based on renewable

sources of energy > Combined heat and power plant> Remote and block heating power

plants > Remote and block cooling > Heat pumpsmust be explicitly reviewed if the netfloor space exceeds 1,000 m².

Generation of heatAs a matter of principle, the energy re-sources available at the building locationand the statutory requirements deter-mine the options available for heat gene-ration. The connection to a remote ornearby heating network is viable for eco-logical reasons. Partial solar room hea-ting, i.e. a heating system supported by asolar system, is an alternative to conven-tional heating systems.

If fossil fuels are used for heating, thebest possible available technology shouldbe used to attain a high utilization leveland to reduce emissions and fuel con-sumption. To this end, the use of highlyefficient thermal value equipment wouldbe expedient.

Heat pumps used in heating systems uti-lize the ambient heat and electrical powerto generate heat. The performance andwork parameter ist used to determine theefficiency of a heat pump. The perfor-mance value COP indicates the ratio ofthe radiated heat to the electrical powerrequired to produce it. The work parame-ter refers to the ratio of the heat volume

radiated in comparison to the energyused. While the performance value re-flects the current value (performance),the annual work parameter provides amore precise statement as to the actualefficiency of the heat pump under realoperating conditions.

Make sure that the heat pump attains aminimum annual work parameter. It mustbe calculated in compliance with Guide-line VDI 4650. For geothermal heatpumps and water heat pumps it shouldbe at least 4.5. The annual work parame-ter can be easily determined with the as-sistance of the heat volume meter andthe electrical meter for the heat pumpand its supporting drives.

Heat distribution Lower upstream temperatures in lowtemperature heating systems are advan-tageous for the use of renewable energies(e.g. heat pumps, solar energy, etc.) andare principally desirable. Depending onthe energy medium used, the heat is usu-ally distributed through water as a me-dium.

Cooling - fundamentalsThe debate as to what appropriate coo-ling systems and sustainable, energy ef-fective systems of supply are isincreasingly not only a hot topic amongengineers and architects, but also amongdecision makers at investors and at cor-porations.

To make such decisions, those involvedhave to have basic knowledge of theterms and technical options. Just like innumerous other technological and busi-ness disciplines, the systems can be allo-cated to various categories anddifferentiated based on their perfor-mance capabilities. Cooling technologiesand applications are primarily dividedinto > passive structural systems > silent cooling with environmental

energy sources > active cooling systems with

ventilation > and if applicable also with

air conditioning.

Passive cooling Passive cooling is achieved without theinvolvement of mechanical drive systemsand is solely based on structural measuressuch as facade and shading optimization,the utilization of storage masses, over-night cooling and design of a micro-cli-mate. The first task in hand is to optimizethe structure of the building, i.e. to usepassive systems to achieve cooling ef-fects.

The direction of the building, the percen-tage of window surface and the directi-ons the windows are facing are keycontrol factors for the minimization ofcooling efforts required once the buildingis occupied.

18

The utilization of modern building mate-rials and the optimization of the storagecapacity play critical roles in terms of thecooling efficiency of a building. Last butnot least, the amenities have to be opti-mized so that the internal loads of thebuilding are limited to the extent wherethey no longer exceed 300 Watts per per-son.

Silent cooling systems: Energy efficiency and comfortSilent cooling systems, such as concretecore activation, floor cooling systems orcapillary ceiling or wall heating bringenergy into the and out of the buildingusing water as the medium. Geothermalsensors, flat collectors below the buildingor parking lot may be used as heating orcooling potential; even fountain systemswith drawing and sink hole wells make itpossible to control the temperature insidethe building without using a refrigerationdevice. Another silent system is the con-trolled overnight cooling throughwindow ventilation, which makes it pos-sible to discharge the storage capacitiesof the building throughout the nightwhile maintaining compliance with safetyand security technical aspects and pro-tects against potential torrentialdownpours.

Active cooling systems: Delivering high performance in conjunction with luxury amenitiesActive systems are divided primarily intowater medium and air medium cooling.

The transportation of cooling effectsthrough water as a medium translatesinto powerful systems: cooling ceilings,cooling sails, but also concrete core acti-vation and capillary ceilings.

Systems working with air as the mediumtransport a substantial portion of theheating and cooling energy through themechanical air inflow and outflow. Onedifferentiates between partial air condi-tioning without humidification and fullair conditioning systems that also controlthe humidity levels in the room.

The active cooling systems can be opera-ted by a variety of systems. Compressorsbased on stroke pistons, screws, scrollingor turbo machines, which deliver the coo-ling effects in combination with a recoo-ling plant, are commonly used.

In optimized use, a combined heat-power-cooling plant, i.e. the simultane-ous production of heating and coolingenergy, can also be an efficient solution.Absorption and adsorption cooling ma-chines use environmental energy resour-ces. The absorption process, for instance,allows the use of solar energy. In combi-nation with the absorption cooling ma-chine an entire solar cooling system canbe created.

Focal points of the energy conceptDuring the heating period: Insulation replaces heating.

In the summer: Storing replaces cooling.

Capillary heatingThe capillary heating system is mountedon the finished wall as a bundle of plastictubes and covered with stucco. Much likeconcrete core activation, capillary heatingtakes advantage of the storage activitiesof the building, albeit to a lesser extent.However, capillary heating systems canbe adjusted more quickly and can also beused in renovation projects.

Consequently, it is a highly efficient sy-stem. Its integration into the constructionprocess is considerably more complex andthe costs are substantially higher thanthose incurred with concrete core activa-tion. If the cooling or heating capacity ofthe wall heating system is not sufficient,it can be complemented with a coolingconvector mounted to the ceiling of theoffice. In this combination, it provides anoptimally controllable system.

Floor cooling systemA floor cooling system, which principallyworks just like a floor heating system,provides significantly less cooling output.At the rate of 15 to 20 W/m² it can trans-port heat out of the room and is easy tocontrol, albeit the required investmentcosts are considerably lower. It can beused for heating or cooling purposes asneeded.

The only conditions that must be met af-fect the choice of the floor covering,which must have good heat and cooling

Integral Planning and Technical Design

19

Scroll Stroke piston Screw as of 125 kWTurbo Absorber

0-250 kW

480 €/kW300 €/kW265 €/kW

2,000 €/kW

250-500 kW

280 €/kW250 €/kW

1,500 €/kW

500-1000 kW

240 €/kW210 €/kW

1,400 €/kW

1000-3000 kW

220 €/kW175 €/kW195 €/kW

1,340 €/kW

3000-9000 kW

160 €/kW160 €/kW145 €/kW

1,400 €/kW

Specific costs for cooling machines with recooling plant without tubing

Source: Gertec Ingenieurgesellschaft

without distributionwithout distributioncomplete with tubing and cooling energy production, no electricityCeiling-/Cassette devices 7-14 kW 520 €/kW heating and coolingWall-/Ceiling devices 2-14 kW 420 €/kW coolingWall-/Ceiling devices 8-14 kW 450 €/kW heating and coolingWindow air conditioner 2- 8 kW 265 €/kW cooling

Cooling ceilings . . . . . . . . Component activation . . .Cassette devices . . . . . . .Splitter devices . . . . . . . . .

125-150 €/kW40-50 €/kW

1,300-1,500 €/kW

Specific costs for cooling ceilings, component activation and fan convectors in cassette devices

Source: Gertec Ingenieurgesellschaft

Passive Cooling Systems Silent Cooling SystemsActive Cooling System

and Climitization

Optimization of exterior loads- Window surfaces and qualities - Wall surfaces and qualities - Sun shading Optimization of interior loads- Equipment (PC, monitors, devices, . . .) Optimization of storage masses- Access to masses (no lowered ceilings) Innovative building materials (PCM)Night cooling

Energy transportation in the room at low temperature levels (12-17°C) -Concrete core activation - Capillary ceilings and walls - Floor cooling

(via floor heating systems) - Cooling sails

Environmental potential- Earth probes - Earth collectors - Fountains/wells - Rivers and lakes - Recooling plant

(hybrid systems with humidification)

Technical cooling- Compression cooling machines

Silent syst. and air conditioning via fresh air and exhaust air syst. - without humidification - with humidification

(+30% for self-use) - with waste heat recovery for

central ventilation systems

Ceiling systems (cassettes)- with cold water supply - with refrigerant supply (split)

conduction properties. What makes floorcooling systems ideal is the fact that theyinstantly absorb the solar energy enteringthe room without increasing the tempe-rature in the room. If the level of comfortof room occupants (cold feet) is adverselyaffected the floor heating can also beoperated only at night.

Cooling ceilingsCooling ceilings are among the mostpowerful cooling systems for office use –however, they are also among the mostexpensive. With a performance potentialof 80 to 120 W/m² they can be integratedinto modern office buildings and are easyto control.

Cooling sails (swamp coolers)Cooling sails or swamp coolers are parti-cularly helpful when installed during re-novation projects. They consist of surfaceor cooling elements that are hung fromthe ceiling. With cooling outputs of 60 to80 W/m², they are easy to control andprovide a powerful solution that can beinstalled in each standard office at anaverage cost of EUR 2,000 to 2,500 perroom or cooling sail. Depending on theinstallation system, they must be coordi-nated with the lighting system. Coolingsails can improve the room acoustics con-siderably.

Concrete core activation with ventilationThe limited controllability of concretecore activation systems can be optimizedif the system is used in conjunction witha ventilation solution. Principally, venti-lation systems are of critical importancefor the air hygiene of interior rooms.

By feeding ventilation air into the room,both hot and cool air can be channeledinto the room. As a result the interiorroom temperature and the fundamentalload can be quickly and individually adju-sted through the concrete core activa-tion.

Heating and cooling with airIf a central ventilation system is installedin the interest of air hygiene, the inflo-wing air can be heated or cooled to con-trol the room temperature. However, thissolution is only adequate as the sole hea-ting or cooling source in extremely wellinsulated passive buildings.

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Energy transportation in the room

Energie-Compilation

Integral Planning and Technical Design

The sole responsibility for the contentof this publication lies with the authors.It does not necessarily reflect the opi-nion of the European Communities. TheEuropean Commission is not responsiblefor any use that may be made of the in-formation contained therein.

Pictures: Josefine Staudinger; Energon SoftwareAG Stiftung, Am Eichwäldchen 6, 64297 Darmstadtu. Asset Manager ProjektM Real Estate GmbH,Friedrich Ebert Anlage 54, 60325 Frankfurt;www.Bardewyk.com; www.pixelio.de - Stihl024;Gertec GmbH