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8/3/2019 IEEE International Conference (2)

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Respecting the thermodynamics principles of

the heat transfer - as the most important

condition for achieving high energy efficiencyin buildings - energy of the ground and heat

pumps - the most reliable alternative energy

sourceDr M. Kekanović *, A. Čeh** and Dr I. Hegediš***

*,**,*** Faculty of Civil Engineering, Subotica, Serbia*[email protected]**[email protected]***[email protected]

Abstract —The solution of accumulating and keeping the

heat in the walls is through insulating from the outside, a

common method used in Europe although it hadn’t been

confirmed on the physical basis, in regards with the

conditions of continental climate, may it be in winter or in

summer. In effect, during summer season part of the heat

gets inside despite the insulations in the walls and over the

night the condition within doesn’t improve as the insulation

would not let it pass through. During winter season, it is

unacceptable to sacrifice solar energy when there is still

plenty of a sunny day, for the reason that the insulation on

the external side of the walls is blocking the sun’s energy.

From aspects of thermodynamics, the best solution would beto set the insulation on the ceiling and to use walls with

optimal thermal insulation thru their entire thickness and at

the same time, which are sound- and fireproof as well. This

article recommends technical solutions, confirmed by

positive feedbacks; StiroFert and a lightweight formwork-

insulating concrete blocks, demonstrate and execute a high

energy efficiency (energy consumption for heating and

cooling of 64 KW/m2 on an annual basis). In order that

heating and cooling system through the use of heat pumps

with downhole heat exchangers and with the coefficient of

thermal efficiency of 1:5 to 1:6, it is necessary to implement

this solution of transferring the solar energy into the ground

around the downhole heat exchangers, so it could be applied

not only individually but also in major cities. Thistechnology would not only return the seized energy from the

ground but could also bring in the ground a much larger

amount of totally free solar energy by transporting through

the thermal oil from solar collectors to the ground around

the downhole heat exchangers. The leading consumers of

energy in the world are buildings. In average, they use 50%

of the total produced energy. The consumption would be

reduced enormously in up to 15% using the described

solution. Thus, the result would be the end of all crises that

have befallen the world (energy, ecological, economic),

improvement of world economy, social development and

prosperity of mankind.

I NTRODUCTION

Several technologies that we use today gives maybemore benefit for certain industries, than for their users. Soit can be believed that in the last fifty years, particularly inEurope, the present practical methods of thermalinsulation of buildings with a very low energeticefficiency were simply forced methods. Thermalinsulation technique of the exterior walls with just fromthe outside, which is being mostly used in Europe, has notyet been proven in real situations and it would be logical

just at first glance, that the heat accumulates and preservesin the walls.

The declarations that this is the only logical way of building insulation, has been accepted without prejudice.Intentionally or not, the laws of thermodynamics - whichare taught even in elementary school – had been forgotten.These laws describe the physical behaviour of thermalenergy, where warm air, as easier, always moves upward -when the medium is gas, but heat transfers throughconduction inside the building materials. This take placefrom a region of high temperature to another region of lower temperature, regardless wherever it is: up, down or on the sides. (Fig1.)

Interestingly, today in the European Union andelsewhere in Europe, the recommended thickness of conventional insulation for exterior walls, is a few tens of

centimetre (from 20cm and even up to 40cm),commended by Directives to raise the energy efficiency of buildings. In this case, the advantage again is for theindustries. On the other hand, ordinary people in general,gets an entirely unnatural substance – "nylon bags", whichobstruct ventilation and diffuse natural environment andwater vapour since the walls are hardly permeable towater vapour (expanded polystyrene) or they need to be

protected with polyethylene films from entering the water vapour (wool). Even with substantial insulation, energyconsumption for heating the buildings in winter is reduced

just slightly but it also consumes even more energy insummer - for cooling. In other words, conventionalsolutions like this would hardly satisfy class A, accordingto „The Directive on Energy Performance of Buildings“



Figure1. Conventional way of building insulation in winter regime Figure 2. Energy efficient way of isolating class A objects -at thewinter regime - with structural built-in insulation in the slabs and

the walls made of light weight formwork-insulating concrete blocks

(2002/91/EC - Directive 2002/91/EC of the EuropeanParliament and of the Council) as a respond on an evidentenergy-, environmental crisis in the world.

A LOGICAL WAY OF BUILDING INSULATION FROM THE ASPECTS OF THERMODYNAMICS

According to the laws of thermodynamics and themovement of warm air as it easily goes upward, in the air,the most important is the ceiling insulation, to avoid hotair from entering into the cold concrete slab.

On the other hand, when the ceiling is not insulated,heat then enters the concrete slabs through conduction – asstated in the laws of thermodynamics - heat would go bythe walls of brick, block or concrete. Walls made in thesekinds of materials are like chimneys, instead of smoke,

they transfer heat by conduction in a vertical direction tocolder places, but are difficult to insulate, likefoundations, balconies, gable walls, the outer parts aroundthe opening of windows and external doors. Thus,obviously in this case, insulation on the outside of exterior walls, partially prevents heat loss by transmission inhorizontal direction but losses by conduction in thevertical sense are not prevented (Fig. 1).

Consequently, conventional thermal insulatingmaterials from the facade should be "moved" in theceiling, where they will be protected and can give morecontribution to energy saving and efficiency, as well asthe rationalization of investment in buildings which isconsidered as the main energy consumers. In regards withconventional concrete slabs, expanded polystyrene, with

at least a 5 cm in thickness should be glued to the ceilingand secured with steel or PVC dowels by placing a glassor PVC mesh in a layer of plaster. Stone wool with thesame thickness can also be set on the ceiling, supportedwith gypsum board hanging substructure. In that way hotair will be prevented from entering the concrete slabs andits circulation in the room will flow in corners or along thewindows. Moreover, condensation in those places will besolved. Compared to the case where we missed to setinsulation in the ceiling, the energy efficiency of the

building should raise by at least 25%.The best solution for the walls would be to have

optimal thermal insulating performance all over their thickness. Heat conduction thru these walls in cold placeswould be prevented, both horizontally and vertically (Fig.2.). The excellent solution for the wall composite isconcrete which is a combination of cement, lime Ca(OH)2

and granulated expanded polystyrene, a hydrophobic

material that does not absorb too much moisture, thatmight reduce the insulating properties of the wall.

These walls would then be, alongside a thermalinsulation (k<0,25W/m2K), vapor permeable andventilated (water vapor transmission rate μ=19,6), soundand fireproof (resistance greater than other conventionalwalls), thanks to their porosity (open and closed).

These walls by summer works like those that are madefrom earth (ie. rammed soil or adobe) Outside, they warmup during the day and cools down overnight (Fig. 3). Thelime contained by the wall, is conventionallyindispensable material, as it disinfects and regulates air quality, microclimate and humidity in the room. Inaddition, the lime also pulls out the moisture from therooms and transfers it to the exterior part of the wall and isthen drained out due to the warming sun.

Some authors based their conclusion in external (380

C)and indoor air temperature (25 0C) in summer that thewater vapor will move from outside to the inside as thesaturation vapour pressure ( p') is higher on the exterior than in the inside of the building ( pe' > p'). This wouldthen mean that the partial pressure of water vapor (pe =φ· pe') is greater outside than within the premises ( pi =φ· pi').This situation happens only if you look at thingssuperficially, overlooking the physical behaviour of theoutside wall that is without moisture. The fact that the sunand wind dries out the outer surface of the wall imply thatthe saturation vapour pressure values will there tend to be

just about equal to zero (pe '= 0%). In truth, it is the limein the walls that pulls out moisture from the rooms to theoutside of the walls and dries out due to the heat of thesun. Therefore, the water vapour during summer is notmoving from outside to inside, but rather it moves in viceversa. This progress should be enabled instead of being

prevented. Finishing of the walls from the inside andoutside may not be a barrier for vapour, but conversely

permeable. Even if the external side of the wall gets wetdue to rainfall, it will soon dry out. So it would be a bigmistake if we put water/vapour barrier for the externalwalls as this will only prevent the natural physical

processes, thus turning the house into a “nylon bag”



Figure 3. Energy efficient way of isolating class A objects - duringthe summer regime - with structural built- in insulation in the slabsand the walls made of a lightweight formwork-insulating concrete

blocks

Figure 4. The conventional way of insulation buildings duringsummer - conditions inhumane for people

Figure 5. Girder-grilled, reinforced concrete floor StiroFertstructure with elements that provide a powerful load bearing

capacity and thermal insulation

The walls should be vapor permeable all the waythrough its whole thickness. In that way, the entire place

would have a pleasant microclimate with less moistureand heated walls alongside the floor slabs giving rise to acondition that decrease the need for air conditioners thatconsumes energy, thus eliminating health risks anddamaged ozone layer. Walls completed all throughout itsthickness to have optimum insulation, would providegreater resistance to heat transfer during winter seasoncompared to conventional insulated walls build today. It isimportant to emphasize as well, that walls insulated all theway through their thickness, would receive most of thefree solar energy at some point in the heating season, fromOctober to April. Such helps to significantly contribute toimprove the energy efficiency of buildings.

On the other hand, walls insulated in the conventionalway (merely from exterior side), would not be able toabsorb the sun's energy and it is such a waste of anentirely free, solar energy. Conventional insulation fromthe exterior walls acquires a fraction of the heat duringsummer but also because of that, recovering at night isfutile (Figure 4). So after a few days, these walls wouldalready be heated besides being barely vapor permeable.From these conditions, air-conditioning is required,otherwise people will have difficulty to function well andlive.

In the light of these recommendations for buildinginsulations, StiroFert are designed, patented and already



Figure 6. Formwork-insulating KekoEko blocks for masonry,made on the basis of granules of expanded polystyrene, cement and

lime, with cavities for reinforcement and concrete

Figure 7. Ground source heat pump

Figure 8. The new system, using the solar energy by solar collectors through the ground around the heat

exchangers and that way renewing the earth's energy - this systemis also applicable for the level of the larger cities

applied on tens of thousands of square meters of floor structure (Figure 5). StiroFert is a structurally permanentinsulated stay-in-place EPS formwork, which makes thisconstruction, to be lightweight, girder-grilled, and withgreat span slab (with a span of over 10 m). The same stay-in-place EPS formwork is also applied to ceiling as a

powerful insulation which has an average thickness of at

least 13 cm and with the thermal conductivity coefficientk<0,25W/m2 K. An excellent finishing for the ceiling isgypsum-lime fireproof plaster and steel mesh. The slabrepresents a perfect fireproof solution, with highresistance against heat and without demeaning thestructure´s mechanical performance, even for a duration(of fire) of several hours.

Designed, patented and applied as lightweightformwork-insulating concrete blocks - EkoKeko blocks(Fig. 6) – are made based on the granules of expanded

polystyrene, cement and lime. EkoKeko blocks havevertical and horizontal cavity that provides reinforcementfor concrete therein. Hence, with only 25 cm wallthickness, loadbearing capacity and construction safety for multistory buildings is achieved. The walls are

simultaneously thermal insulated, soundproof, vapor permeable, fireproof - with features that were mentioned before now in this article. Feedbacks concerning theenergy efficiency from existing buildings which weremade with StiroFert-slab solution and formwork-insulating EkoKeko blocks, shows that the energyconsumption in residential houses, all throughout the year,is between 58 and 64 kW/m2.

In the case of walls made from bricks or adobe, or hollow clay blocks, mortar with some thermal insulating

properties should be use instead of regular mortar, withcoating of 6 to 8 cm on the outside and 3 to 4 cm inside.Ceiling insulation is mandatory for high energy efficiencyand climatic conditions would then be satisfied as insummer or in winter.

For existing buildings, chiefly multistory, the simplestway of raising the energy efficiency is to insulate theceilings in the manner as described, and by placing a cork on the interior side of the walls with thickness of at least10 mm. Such is needed to be done if there is no possibilityto use thermo-plasters on facade with previously describedthickness.

THE GROUND AS A RELIABLE ALTERNATIVE ENERGY SOURCE

Objects, warmed by ground source heat pump and withsuggested insulating solutions, would be highly energyefficient, with the efficiency coefficient of at least 1:5 or even up to1:6. This coefficient of efficiency depends onthe construction of the heat pump, hydraulic of flow, andmostly on how well the building was insulated.Particularly in the case of large heating surface such as

floor or wall, the water temperature onset should not begreater than 28 0C and 24 0C when it returns back.The ground energy is by far the most reliable

alternative energy source compared to others. Heating andcooling using heat pumps have long been used in Europeas well as with the other part of the world, although onlyin individual cases. In fact, present solution for groundsource heat pumps is not applicable to be used to a levelfor the whole cities, as it would exhaust the energy fromthe ground and would result to the deteriorating of groundtemperature, thus making the system unprofitable. Therisk of negative impact on the earth's core should also beconsidered, if the current system of geothermal heat

pumps would be applied to the level of larger cities, withmuch greater lengths of boreholes (much more than 120

m), using the earth's energy from greater depths

(Figure 7).In this article, presented is a solution that is registered

as a patent and consist a fact that using solar collectors totransport the sun's energy in the ground around thedownhole heat exchangers, in equal amount as the power

drawn from the ground or greater. Specifically, a spiraltube made of thin stainless steel wrapped around the outer side of the heat exchanger and then lowered into the



ground. The solar energy is transported through this tube by thermal oil from solar collectors and to the groundaround the heat exchanger. The earth would accumulatethat energy (Figure 8). With this technology, drainedenergy from the ground returns or can transfer an evenlarger amount of totally free solar energy. In that case, thecapacity of the heat exchangers would be much higher

than the current 70W/m1

. Energy intake around the heatexchanger into the ground could start immediately at latesummer until the end of the heating season. After that

period, the ground cools down till next summer, thusavoiding the conventional air conditioning as the samesystem can be use to cool down buildings as well.

With this patented solution adverse disturbances can beavoided and can be applied to cities, regardless of their size. Ice-covered streets in winter in cities could beavoided also.

CONCLUSIONS

The solution of keeping the accumulated heat in thewalls, insulated on the exterior side, which is currentlyused mostly in Europe, is as impractical as the solution tosave power in batteries. Therefore, it would be wiser touse walls and floor structures (strictly observing the lawsof physics and thermodynamics), as it is described in thisarticle - that would enable consumption of minimumamount of energy of less than 60 kW/m2 yearly, includingheating and cooling. Such building system that isimproved with heating and cooling system using thedescribed heat exchangers with heat pumps, (using themost reliable alternative energy from the ground and fromthe sun), would result to a total consumption of energy

below 15 kW/m2 yearly. This solution wouldautomatically reduce the need for the most hazardous

sources of energy by combustion and splitting the heavyatoms. Thus, the emission of greenhouse gases isenormously reduced as the adverse effects of "greenhousegases". In order to apply heating and cooling system usingheat pumps with heat exchangers, not only individually

but also in major cities, it is necessary to make a new oneas described in the solution, by transferring solar energyinto the ground close to heat exchangers. With thistechnology, seized energy from the ground can be

replaced, or it can transfer an even larger amount of entirely free solar energy, transporting it through thethermal oil with solar collectors around the heatexchangers in the ground.

Globally, buildings are the largest consumers of energyand on average, uses over 50% of the total energy

produced. These solutions would enormously reduce the

consumption of energy. The result: end of all crisis thathave befallen in the world (energy, ecological, economic),improvement of economy, social development and

prosperity for mankind.

R EFERENCES

[1] M. Kekanović: Priznati patent pod brojem 50224 - Mogućnost specijalnog olakšanja, izolovanja i armiranja međuspratnihkonstrukcija, Glasnik intelektualne svojine, 15.07.2009.

[2] M. Kekanović: Priznati patent pod brojem 50934 – Laki betonskielementi za zidove i međuspratne konstrukcije, Glasnik intelektualne svojine, 31.08.2010.

[3] M. Kekanović: Priznati patent pod brojem 50270 – Postupak za proizvodnju peno-polistiren-perlit-betona, Glasnik intelektualnesvojine,15.07. 2009.

[4] M. Kekanović: Priznati patent pod brojem 49444 – Postupak zadobijanje betonskih, keramičkih, izolacionih, modularnih, fasadnih, ekoloških, nosivih elemenata, Glasnik intelektualnesvojine,03.03.2006.

[5] M. Kekanović: WO/2001/059794 – Heat Echanger for geothermal heat-or cold , WIPO,16.08. 2001.

[6] M. Kekanović., A. Čeh: Polumontažne superlake kasetiraneStiroFert armiranobetonske konstrukcije, 15. Zbornik radovaGrađevinskog fakulteta u Subotici, Subotica, 2006.

[7] M. Kekanović,I. Hegediš, A. Čeh , Z. Kljajić: Građenje stambeno poslovnih objekata visoke energetske efikasnosti, 18. Zbornik radova Građevinskog fakulteta u Subotici, Subotica, 2009.

[8] M. Kekanović, M. Kustudić , Z. Kljajić : Katalog savremenihgrađevinskih konstrukcija, StiroFert doo, Vrbas, 2009.

[9] Directive 2002/91/EC of the European Parliament and of theCouncil , 2002.

[10] M. Kekanović , A. Čeh: Polumontažne superlake kasetiraneStiroFert armiranobetonske konstrukcije, 15. Zbornik radovaGrađevinskog fakulteta u Subotici, Subotica, 2006.

[11] M. Kekanović ,A. Čeh , Z. Klajić : Roštiljno-kasetne međuspratne ploče velikih raspona kao sistem za građenje stambeno poslovnihadaptabilnih objekata, INDIS 2009, Novi Sad

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