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Energy and Buildings 92 (2015) 45–54

Contents lists available at ScienceDirect

Energy and Buildings

j ourna l ho me page: www.elsev ier .com/ locate /enbui ld

nternal environment in the museum building—Assessment andmprovement of air exchange and its impact on energy demandor heating

oanna Ferdyn-Grygierek ∗, Andrzej Baranowskiepartment of Heating, Ventilation and Dust Removal Technology, Silesian University of Technology, Konarskiego 20, 44-100 Gliwice, Poland

r t i c l e i n f o

rticle history:eceived 7 July 2014eceived in revised form6 December 2014ccepted 20 January 2015vailable online 29 January 2015

a b s t r a c t

The paper presents the results of the analysis of the impact of various ventilation systems on the energyconsumption performed for one Polish museum building that was built in 1929–1930. Simulations werecarried out with the use of two computer codes: CONTAM and ESP-r. Multi-zone models including theexhibition rooms and the staircase were prepared. The simulations were made of synthetic weather datafor one of the Polish towns for two months of the heating season. Twenty-four hour variability of internalheat gains was taken into account. The results show clearly that the natural ventilation system (which

eywords:useum

entilationir change rateuilding simulation

is currently used in the building) enables the air exchange with fresh air on the first floor only. The airinfiltration on the upper levels is close to zero. Rebuilding the ventilation system generates changes inthe energy demand of the building. It is presented how the heat demand increases with the increase ofthe ventilation air flow and what is the impact of the air infiltration on the heat demand for differentvariants of ventilation.

eating demand

. Introduction

Parameters of internal environment in buildings are strictlyependent on the function that these buildings perform. For generalurpose premises such as apartments, offices, etc., determinationf the requirements for internal air quality is precisely defined,or example by appropriate standards. In special purpose facili-ies, e.g. museums, the determination of desired or even necessaryarameters of indoor environment is difficult and ambiguous. Thestablished and maintained indoor environment parameters in theuseum premises must be appropriate both to ensure proper con-

itions to prevent degradation of the objects due to external factorsnd to create comfortable indoor environment for visitors.

Three groups of threats to the museum collections can be dis-inguished:

hygrothermal conditions of the environment,

air pollution: dust, chemical, biological,excessive internal gains (lighting, heat and humidity gains fromthe people).

∗ Corresponding author. Tel.: +48 32 237 2912; fax: +48 32 237 2559.E-mail addresses: joanna.ferdyn-grygierek@polsl.pl (J. Ferdyn-Grygierek),

ndrzej.baranowski@polsl.pl (A. Baranowski).

ttp://dx.doi.org/10.1016/j.enbuild.2015.01.033378-7788/© 2015 Elsevier B.V. All rights reserved.

© 2015 Elsevier B.V. All rights reserved.

The level of threat posed by these factors is different for dif-ferent types of collections. In some countries, especially in thosewith a large number of historic monuments, there are appropri-ate regulations determining optimum environmental factors forthe protection of the exhibits on the museum premises [1,2]. Someguidance regarding the environmental conditions can be found inASHRAE publications [3,4].

Removal of the above threats can be accomplished by variousmeans, both through the use of appropriate technical solutions, e.g.dehumidification or humidification of museum rooms which are atrisk, heating, cooling and air-conditioning of exhibition halls [5,6],as well as through the protection of the exhibits by the use of closeddisplay cases, special display cassettes, etc. [7,8].

In order to determine the optimum microclimatic conditions inthe exhibition halls it is necessary to assess the current state. Theassessment is carried out by monitoring temperature and relativeair humidity [9–12] as well as CO2 concentration, the latter beingan indicator used to evaluate heat gains from the visitors [13], andthe quality of the ventilation in the building [14]. Particular atten-tion should be paid to sharp peaks in temperature and air humidity,because instantaneous acute changes in these parameters are dan-gerous to the exhibits. As to other threats, the monitoring can be

more sophisticated than simple tracking of changes in temperatureand air humidity. This concerns especially the level of gaseous pol-lutants on the premises, monitoring of which requires advancedtechnologies [15].

46 J. Ferdyn-Grygierek, A. Baranowski / Ener

lpmTcsfdmiseto

twTnt

cpit[wctem[

impasoh

2

f1mre

3 0.67

Fig. 1. The museum building selected for the analysis.

Ensuring proper parameters of indoor environment depends to aarge extent on proper ventilation of the exhibition galleries. Appro-riate level of air exchange allows both removing the excess ofoisture and heat from the premises, and reducing air pollution.

he optimal solution is to equip the museum premises with the air-onditioning system. The strategy for the use of the air-conditioninghould be carefully planned. The way it is used should be optimalrom the point of view both ensuring proper microclimatic con-itions and energy saving. Many historical museum buildings areassive ones. The studies [16] show that night ventilation for cool-

ng of such buildings in summer can be applied. When indoor andolar gains are accurately controlled and minimized, the synergicffect of high thermal mass of the building and nocturnal air ventila-ion allows maintaining appropriate conditions for the preservationf museum objects without the use of mechanical cooling system.

It should be noted that the use of the air-conditioning sys-em may result in rapid changes in temperature and air humidity,hich can be harmful to the exhibits in the exhibition rooms [9].

o develop an optimal strategy for the use of the air-conditioning,umerical simulations using building energy performance simula-ion codes [17–21] are useful.

In some cases, the improvement of the ventilation system isonsiderably impeded due to historic nature of the facilities androhibition against any interference in the structure of the build-

ng. In some historic buildings there are architectural structureshat can be considered as a kind of natural ventilation system22]. Medieval buildings often have natural ventilation ducts whichere deliberately constructed. In both cases, it makes sense to

heck the effectiveness of working of this kind of ventilation. Dueo their nature, historical building offer limited possibilities fornvironmental conditions measurement. Consequently, one of theethods to evaluate the ventilation system is computer simulation

23].The paper presents the results of numerical simulation of var-

ous ventilation systems which could be applied in one Polishuseum where only natural ventilation currently occurs. The pro-

osed ventilation systems were analysed in terms of air exchangend their impact on heat demand. The results of the study pre-ented in the paper are only a part of larger project. The analysesf internal environment in terms of air temperature and humidityave been described in detail in a separate publication [20].

. Description of the analyses

The museum located in Upper Silesia of Poland was selectedor the analyses. It is double-winged five-storey building erected in

929–1930 and was specially designed for exhibition purposes. Theain entrance is in the west part of building (Fig. 1). The exhibition

ooms are located on the first, second and third floors. The totalxhibition area amounts to: 250 m2 (Flora&Fauna exhibition) and

gy and Buildings 92 (2015) 45–54

170 m2 (Temporary exhibition) on the first floor, 860 m2 on thesecond floor (Ethnography exhibition) and 630 m2 on the third floor(Gallery of Painting). The height of exhibition rooms is about 3.6 m.

The building has mixed walls construction—made partly of rein-forced concrete and partly of bricks. The building is equipped withvarious types of windows (wooden, aluminium, PVC). The windowpanes on the west side are covered with anti-reflection coating.Additional ways of protection from the sun at the exhibitions areinternal blinds and plasterboard walls separating the room fromexternal partitions. The building is equipped with the central heat-ing system with radiators. There is the heating and cooling systemwith fan coils in the Gallery of Painting hall. The major disadvan-tage of this building is the lack of a ventilation system. Originallythe building was equipped with a mechanical ventilation system.After World War II, the old-fashioned and not modernized systemwas dismantled but no new system was installed instead. Currentlythe whole ventilation of the building is provided by means of infil-tration only.

The analysis was performed with the use of two computer codes:CONTAM, the programme designed for multi-zone analysis of theventilation and indoor air quality in buildings [24]; and ESP-r, theenergy simulation system which is capable of energy and fluid flowsmodelling [25]. Due to the aim and requirements of the study, itwas decided to represent the building in the form of multi-zonemacro-scale models. In such a model the building is represented asa series of idealized zones with constant parameters of air withinthe entire zone. The zones are connected with each other and withthe external space by the flow paths of the air or heat that reflectthe actual paths of the energy and mass exchange.

Two numerical models were built: the first one, CONTAM model,was used to simulate the ventilation air flow in the building. Theresults of the simulation were used as an input data in the sec-ond model—ESP-r thermal model. The zoning was assumed in bothmodels, which was imposed by very complicated internal struc-ture of the building. All simulations were performed with 1-h timestep for weather data from the local meteorological station for theperiod from 1 January to 30 September 2010.

3. Simulation analysis of the air flow

Multi-zone numerical model of the museum, representing allidentified air flow paths both infiltrating through the cracks of win-dows and doors as well as inter-zone air flows, was built. The modelincludes exhibition rooms on three floors and the whole staircase.The model did not include the ground floor (there is no connectionbetween the ground floor and the part of the building that housesexhibitions, and thus there is no air flow path) and the rooms on thefifth floor (it is the unused part of the building connected with thestaircase only through one closed door). The staircase was modelledfrom the level of the entrance to the exhibition area, up to the topfloor of the building. The staircase located centrally in the building– having the nature of the atrium – is a potentially important pathof air flow throughout the building. The staircase was modelledas a vertical series of zones connected by low resistance openingsthrough the floors. Fig. 2 shows three levels of the museum buildingrepresented in the CONTAM program.

One of the biggest uncertainties was the value of the air infiltra-tion coefficient, which describes air tightness of the windows. Airinfiltration coefficients were adopted based on the literature dataverified by the authors’ own measurements [26,27]. After the modelcalibration the air infiltration coefficients were set as follows:

PVC and wooden windows: a = 0.2 m /(m h Pa ), aluminium win-dows: a = 0.5 m3/(m h Pa0.67), entrance door: a = 1.0 m3/(m h Pa0.5),internal doors: a = 1.5 m3/(m h Pa0.5). Temperature in the modelwas kept at 20 ◦C in exhibition rooms and 18 ◦C in corridors.

J. Ferdyn-Grygierek, A. Baranowski / Ener

3

if(tStpmtwta

tpocesoosmbiaw

Fig. 2. Model of the museum for calculations using CONTAM code.

.1. Model calibration and validation

The major source of uncertainty in models representing air flowsn the building is air permeability of the windows. In the studiedacility it was impossible to carry out appropriate measurementse.g. pressure tests). To verify the validity of the simulation results,he recorded CO2 concentration in the museum premises was used.ince there were no sources of CO2 in the halls, it was assumedhat the reason for the variation in CO2 concentration was theresence of the people in particular premises. In order to deter-ine air exchange in particular museum halls the method of the

racer gas concentration decay was used [28]. The obtained resultsere compared with the simulation results in order to modify

he air infiltration coefficients for windows that had been initiallyssumed.

Model calibration was performed for the simulation results forhe period from 1 to 31 March, because at that time the museumremises were monitored several times by checking the numberf visitors, which allowed to state that the recorded peaks in CO2oncentration were not random. The results of calculations of airxchange based on the measurement of CO2 concentration decayhould be treated as approximate figures, as there was no wayf guaranteeing that the tracer and the air had been mixed thor-ughly in a large room. Fig. 3 presents exemplary results of theimulation for two different coefficients of air infiltration (of unit

3/(m h Pa0.67)) for the hall on the first floor (Flora&Fauna exhi-ition). It was assumed that smaller value of the coefficient of air

nfiltration is more realistic (in the whole period of the simulationir change rate is closer to the measurement results) and this valueas adopted for further calculations.

gy and Buildings 92 (2015) 45–54 47

3.2. Case studies

The aim of the calculations was to examine air exchange andinfiltration in particular exhibition halls for actual conditions of thelocal climate.

The following four cases were simulated:Case 0: existing natural ventilation system.Case 1: exhaust ventilation system by roof fan of constant air

flow rate ((a) 1000 m3/h, (b) 3000 m3/h, (c) 5000 m3/h), locatedabove the staircase.

Case 2: exhaust ventilation system by fans of constant air flowrate (1000 m3/h), located in each exhibition room.

Case 3: mechanical, supply and exhaust ventilation system—supply fans located in the Ethnography hall (600 m3/h) and theGallery of Painting hall (600 m3/h), and one roof exhaust fan withconstant air flow rate (3000 m3/h) located above the staircase.

3.3. Results and discussion

When calculating and presenting the results one should dis-tinguish between air exchange and infiltration. Air exchange iscalculated from the balance of all air fluxes flowing through thezone in question and thus also the streams from the adjacent rooms(it is the sum of air flow through the windows from the outsideand through the doors from or to the adjacent rooms), whereas airinfiltration is calculated as air flows between a given zone and thesurroundings of the building (it is only fresh air inflowing from theoutside through the windows).

Figs. 4–10 present air change rate in exhibition halls calculatedas the sum of air flows infiltrating from the outside of the buildingin relation to the volume of a given zone (infiltration) or as the sumof all air flows (infiltrating from the outside of the building andinflowing from the adjacent premises, e.g. from the staircase) inrelation to the volume of a given zone (air exchange).

As shown in Figs. 4 and 5, the air exchange is generally greaterthan the infiltration. The simulation results show that the high-est level of air infiltration into the building takes place mainly inthe rooms on the first floor of the museum. However, these aresmall values–of approximately 0.15 h−1 (130 m3/h) for the ana-lysed period in the Flora&Fauna hall and about 0.13 h−1 in thehall of temporary exhibitions (75 m3/h). On upper levels externalair infiltration is insignificant (Fig. 4): the average in the halls ofEthnography and Gallery of Painting amounts to about 0.01 h−1

(30 m3/h). The total air exchange on these floors is slightly bet-ter (Fig. 5), because due to the lack of ventilation ducts the airfrom the halls on the first floor flows into the staircase, and theninto the rooms on the upper levels. However, the air change rate istoo small, even in relation to the minimum hygiene requirements.The average value in the analysed period in the Gallery of Paint-ing amounts to 0.12 h−1 (270 m3/h), and only 0.04 h−1 (37 m3/h) inthe Ethnography hall. Table 1 contains mean, maximum and min-imum air change rate for the selected months. On the second andthird floor air change rate is definitely too small and the method ofventilation is improper—as a result, mainly stale air, not fresh out-side one flows into the exhibition rooms. Air change rate decreaseswith the increase in outdoor temperature. As an example, the aver-age value of air change rate in the Flora&Fauna room amounts to0.28 h−1 in February, 0.16 h−1 in April, and only 0.11 h−1 in July.

The simulation results showed that in case of the staircaselocated centrally in the building, thermal buoyancy that causes ver-tical air flow (about 300 m3/h) is generated. Forcing greater air flowin the staircase may cause an increase in air infiltration through the

windows in particular exhibition halls.

Analysing the results for the case 1 it can be seen that alreadyin the first case (case 1a) the air change rate both on the secondand third floor significantly increases (Fig. 6), mainly due to the

48 J. Ferdyn-Grygierek, A. Baranowski / Energy and Buildings 92 (2015) 45–54

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1/Jan 10/Jan 19/Jan 28/Jan 6/Feb 15/Feb 24/Feb 5/Mar 14/Mar 23/Mar 1/Apr

Air c

hang

e ra

te,

h-1

Date

a=0.5 a=0.2 measurement

Fig. 3. Comparison of air change rate on the first floor (Flora&Fauna exhibition) for different parameters of window tightness.

0.0

0.1

0.2

0.3

0.4

0.5

1/Jan 31/Jan 2/Mar 1/Apr 1/May 31/May 30/Jun 30/Jul 29/Aug 28/Sep

Infil

trat

ion,

h-1

Dat e

Flora&Fauna, 1st floor

Ethnography, 2nd floor

Gallery of Painting, 3rd floor

Fig. 4. Variation of air infiltration over time in three exhibition halls of the museum for the case 0.

0.0

0.1

0.2

0.3

0.4

0.5

1/Jan 31/Jan 2/Mar 1/Apr 1/May 31/May 30/Jun 30/Jul 29/Aug 28/Sep

Air

exch

ange

, h-

1

Dat e

Flora&Fauna, 1st floor

Ethnography, 2nd floor

Gallery of Painting, 3rd floor

Fig. 5. Variation of air exchange over time in three exhibition halls of the museum for the case 0.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1/J an 31/J an 2/Mar 1/Apr 1/May 31 /May 30 /Jun 30 /Jul 29 /Aug 28 /Sep

Air e

xcha

nge,

h-1

Date

Flora&Fa una , 1st flo or

Ethnography, 2nd floor

Gallery of Pain tin g, 3rd flo or

Fig. 6. Variation of air exchange over time in three exhibition halls of th

e museum for the case 1a (exhaust of 1000 m3/h in the staircase).

J. Ferdyn-Grygierek, A. Baranowski / Energy and Buildings 92 (2015) 45–54 49

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1/J an 31/J an 2/Mar 1/Apr 1/May 31 /May 30 /Jun 30 /Jul 29 /Aug 28 /Sep

Air e

xcha

nge,

h-1

Date

Flora&Fa una , 1st flo or

Ethnog raph y, 2nd flo or

Gallery of Pain tin g, 3rd flo or

Fig. 7. Variation of air exchange over time in three exhibition halls of the museum for the case 1b (exhaust of 3000 m3/h in the staircase).

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1/J an 31/J an 2/Mar 1/Apr 1/May 31 /May 30 /Jun 30 /Jul 29 /Aug 28 /Sep

Air e

xcha

nge,

h-1

Date

Flora&Fa una , 1st flo or

Ethnog raph y, 2nd flo or

Gallery of Pain tin g, 3rd flo or

Fig. 8. Variation of air exchange over time in three exhibition halls of the museum for the case 1c (exhaust of 5000 m3/h in the staircase).

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1/J an 31/J an 2/Mar 1/Apr 1/May 31 /May 30 /Jun 30 /Jul 29 /Aug 28 /Sep

Air e

xcha

nge,

h-1

Date

Flora&Fa una , 1st flo or

Ethnog raph y, 2nd flo or

Gallery of Pain tin g, 3rd flo or

Fig. 9. Variation of air exchange over time in three exhibition halls of the museum for the case 2 (exhaust of 1000 m3/h in the exhibition halls).

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1/Jan 31/Jan 2/Mar 1/Apr 1/May 31/May 30/Jun 30/Jul 29/Aug 28/Sep

Air

exch

ange

, h-

1

Dat e

Flora&Fauna, 1st floor

Ethnography, 2nd floor

Gallery of Painting, 3rd floor

Fig. 10. Variation of air exchange over time in three exhibition halls of the museum for the case 3 (exhaust of 3000 m3/h in the staircase, supply of 600 m3/h in the halls ofEthnography and Gallery of Painting).

50 J. Ferdyn-Grygierek, A. Baranowski / Energy and Buildings 92 (2015) 45–54

Table 1Air exchange and infiltration (italic) in the museum (case 0).

Floor/exhibition February April July

Mean Max Min Mean Max Min Mean Max Min

h−1

First floor/Flora&Fauna 0.280.28

0.400.40

0.090.09

0.160.15

0.300.30

0.000.00

0.110.03

0.260.16

0.000.00

First floor/temporary exhibition 0.250.23

0.360.33

0.070.04

0.140.12

0.270.05

0.000.00

0.100.003

0.230.03

0.000.00

First floor/corridor 1.240.04

1.760.07

0.380.01

0.640.004

1.330.05

0.020.00

0.440.003

1.110.03

0.000.00

Second floor/Ethnography 0.050.004

0.090.06

0.020.00

0.040.01

0.090.06

0.000.00

0.030.01

0.060.05

0.000.00

Second floor/corridor 1.150.002

1.620.04

0.360.00

0.600.004

1.220.04

0.010.00

0.410.002

1.030.03

0.000.00

Third floor/Gallery of Painting 0.190.00

0.260.03

0.060.00

0.100.004

0.200.07

0.010.00

0.070.05

0.170.15

0.000.00

.62

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Third floor/corridor 1.160.002

1.590.00

0.370.03

00

mprovement of air infiltration on these floors. By increasing theow of exhaust air to 3000 m3/h (case 1b), the satisfactory level of.4–0.5 h−1 air exchange is obtained in the halls of Ethnography andallery of Painting (Fig. 7). The beneficial influence of the exhaustir on the stabilisation of air change rate throughout the simulationeriod should be emphasized. The fluctuations of air change raten the lowest floor result from the fact that the infiltration, whichetermines the air exchange in these parts of the building, changesccording to outdoor temperature fluctuations and wind action.

The exhaust of 5000 m3/h of air (case 1c) further improves their exchange on all floors. The calculated air change rate (Fig. 8)orresponds to the flux of approximately 600 m3/h of the air onach floor.

In the case 2, a single exhaust of air with the flow of 1000 m3/h inach of the three main exhibition halls was assumed. The obtainedesults (of the air change rate) are similar to the case 1 (Fig. 9),xcept in the Gallery of Painting, where the ventilation air flow isreater.

The use of direct air supply to the exhibition rooms (case) results in the equalization of the air exchange in the build-

ng (Fig. 10). Air exchanges in the exhibition halls are similar0.4–0.5 h−1 on average).

One should emphasize a favourable impact of air exhaust onhe stabilization of the air change rate during the whole simulationeriod. The fluctuations in the air change rate on the lowest floorcase 0) result from the fact that air infiltration, which changesccording to outdoor temperature fluctuations and wind impact,etermines these exchanges.

The summary of the air change rate (mean, maximum and min-mum values in considered period from January to September) isresented in Table 2.

Proper air change rate to ensure the protection of the exhibitss not clearly defined by any standards. The protection of collectiontems aims mainly at maintaining proper temperature and rela-ive humidity in the rooms. In typically used standard museumshere are no sources of pollution, which would require very inten-ive air exchange (obviously it does not apply to the world-famousalleries and museums with a large number of visitors contribut-ng to the significant heat and humidity gains). Consequently therere no explicit criteria for choosing the optimal solution. It can bessumed that air exchange at the level of 0.4–0.5 h−1 is completelyufficient for the removal of possible pollution in the examined

useum. It is also a satisfactory value from the point of view of air

uality for the visitors. Polish standard for public buildings specify0 m3/h per person as the required air flow. The air change ratet the level of 0.5 h−1 provides the requisite air flow for 15 to 75

1.220.03

0.010.00

0.420.004

1.030.04

0.000.00

people—depending on the location of the room. The average num-ber of visiting groups ranges from 15 up to 30 people. On the otherhand, large air exchange can have an undesirable effect as it causesadditional dehumidification of air and makes it impossible to main-tain appropriate environmental conditions in storage areas [29,30].

When analysing the obtained results, one can observe that noneof the variants meets such a criterion accurately. Most equalizedair change rate can be obtained when using the case 3—the combi-nation of the exhaust through the staircase roof with the supplyof the air in the worst ventilated rooms (the Ethnography andGallery of Painting halls). For this variant, the average air changerate in all halls is close to 0.5 h−1. The solution 1b can be con-sidered as a minimal variant—the minimum air change rate doesnot fall below 0.3 h−1 in any room. Exceeding one air exchangeseems aimless. When taking into consideration the volume of thepremises, air flows for such volumes of facilities are from 800 to3000 m3/h. Improper supply distribution could be harmful to theexhibits because of the possibility of the occurrence of too high airvelocities.

4. Analysis of the impact of ventilation systems on heatdemand

The model of the museum consisting of nine zones coveringthe following rooms of total volume of 8008 m3 was built in ESP-rprogram:

• first floor: Flora&Fauna exhibition hall—one zone, temporaryexhibition hall—one zone, corridor—one zone, vestibule—onezone,

• second floor: Ethnography exhibition hall—two zones (due to thelarge number of partitions it was impossible to model the roomas a single zone), corridor—one zone,

• third floor: the Gallery of Painting—one zone, corridor—one zone.

The following fluxes are computed in the thermal model of thebuilding:

• heat fluxes through the external and internal partitions (walls,floors, windows) that occur due to air and surface temperaturesand climate data,

• heat fluxes due to solar radiation transmitted through andabsorbed by external surface (walls and windows) and solar radi-ation absorbed by different internal surfaces,

• heat fluxes transferred with the air infiltration into the building,

J. Ferdyn-Grygierek, A. Baranowski / Energy and Buildings 92 (2015) 45–54 51

Table 2Air exchange in exhibition halls of the museum for different ventilation variants.

Case Flora&Fauna Ethnography Gallery of Painting Temporary exhibition

Mean Max Min Mean Max Min Mean Max Min Mean Max Min

h−1

0 0.18 0.50 0 0.04 0.12 0 0.12 0.32 0 0.16 0.44 01a 0.32 0.65 0.04 0.14 0.21 0.10 0.14 0.28 0.07 0.29 0.58 0.011b 0.74 0.96 0.58 0.38 0.41 0.36 0.44 0.52 0.34 0.37 0.41 0.351c 1.17 1.35 1.05 0.62 0.64 0.60 0.88 0.90 0.86 1.04 1.20 0.932 0.96 1.07 0.90 0.37 0.41 0.34 0.53 0.58 0.49 0.96 1.07 0.90

0.37

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3 0.48 0.79 0.27 0.39 0.46

sensible and latent casual heat gains emitted by occupants andlights.

All walls of the building were modelled according to the actualtate. Internal partitions adjoining the rooms that had not beenodelled were assumed as adiabatic. Adjacent buildings that may

rovide shade for the modelled building were also included in theodel.The temperature was kept at 20 ◦C in the exhibition rooms and

8 ◦C in the corridors. Twenty-four hour variability of internal heatains was taken into account (the number of visitors was assumedccording to the existing data, gains from the lighting were adoptedccording to the inventory). It was assumed that people stay inhe zones between 10 am and 3 pm. The amount of heat for oneerson was adopted according to ASHRAE [31]: Qsensible = 75 W,latend = 55 W. It was assumed that it takes 1 h for one person toisit the museum, the lighting is switched on for 2 h, and then theverage heat gain for visiting hours was determined.

.1. Model validation and calibration

The preliminary calculations were made and the results of theimulation were compared with measurement results.

The validation was performed for indoor temperature foron-heating season (from mid-June to late August) of all non-air-onditioned zones of the building. The Gallery of Painting with aemperature regulated throughout the whole year was excludedrom the comparison. When conducting the study it was assumedhat there were no internal heat gains, as they are minimal in theummer season. Thus one of the most uncertain parameters wasxcluded. Subsequently the tuning of the model to the real objectas performed.

Fig. 11 presents the course of variation of numerically calculatednd measured average daily indoor temperature in two zones. Per-entage differences are presented in Table 3. Empirical verificationegarding indoor temperature makes the results of the simulationalculations reliable—the relative error is small. The differences doot exceed the value of 10% in any of the zones, and for more than0% of the time they do not exceed 5%.

The results obtained with the use of numerical calculations areufficiently close to those obtained by measurements. The coursesre characterized by large convergence. Based on that, it can betated that the presented model is characterized by sufficient accu-acy and can be used for thermal calculations of the building.

.2. Results and discussion

The solutions aimed at improving the ventilation of the museum

nfluence the change in heat demand for heating up infiltrating airnd total heat demand of the building.

The simulations were performed for the selected, above ana-ysed, ventilation variants: case 0, case 1b, case 2 and case 3.

0.48 0.61 0.37 0.43 0.70 0.24

Each of the cases was simulated for two months of the heatingseason—February (one of the coldest months) and April (transi-tion period when heating system still works during the days withlow external temperature and can be turned off in time of higherexternal temperature, in the whole building or locally in rooms) atone-hour time step, using real weather data.

Fig. 12 presents monthly (February) heat demand of fourmuseum halls for different ventilation variants. The demand forventilation is specified. It can be seen that in the basic variant(case 0) only the rooms on the first floor (Flora&Fauna exhibitionand temporary exhibition halls) are ventilated with an outdoor air(Fig. 12a and b). The air infiltration on the upper floors is close tozero (Fig. 12c and d). The heat demand in cases 1b and 2 is similardue to the fact that total exhausted air flow is the same; howeverthe air change rate is bigger in all rooms for the case 2.

During further analyses it was examined how the demand forpower for heating increases compared to the case 0, and what is thepercentage share of air infiltration in total heat inputs for differentvariants.

The average monthly increase in average daily power for heatingin February (in relation to the case 0) is similar in all halls. It is, how-ever, variable due to the used ventilation system. In the cases 1band 2 it ranges from 30 to 35% and in the case 3 it is lower—rangingfrom 14 to 18% (Fig. 13, left). In warmer April (Fig. 13, right)when losses resulting from heat penetration through the exter-nal walls decrease, the average daily thermal power increases withthe increase of the amount of ventilation air. The largest increase,almost 1.5 times, occurs in the Gallery of Painting (cases 1b and 2).In other halls the power increases from 30% for the case 3 to 80%for the cases 1b and 2.

The percentage of heat for ventilation in total heat demandchanges in particular cases (Fig. 14). Compared to the case 0, thehighest increases occur in the Gallery of Painting and the Ethnogra-phy hall, where the infiltration is the lowest. The use of mechanicalexhaust ventilation causes an increase in the infiltration. The shareof heat demand for heating up the ventilation air in April in exhibi-tion halls ventilated naturally (case 0) practically does not change inrelation to cooler February. After the implementation of mechanicalventilation the share of heat demand for infiltration, in relation toFebruary, slightly increases—on average from 8 percentage pointsin the cases 3 to 10 percentage points in the cases 1b and 2.

The total monthly heat demand for the whole building (all mod-elled zones) for different proposed ventilation systems was alsoanalysed (Table 4). Having analysed the total heat demand for thebuilding (all modelled zones) in February, it can be concluded thatthe largest growth in heat demand occurs when the cases 1b and 2are used (around 30% more than in the case 0). The greatest impactbelongs to the increase in heat demand for heating much larger

infiltration flow (nearly 6-fold increase). Slighter increase in heatdemand occurs in the case 3. During the transition period (April),the increase in heat demand is much smaller due to the increasein outdoor air temperature. Even the decrease in heat demand for

52 J. Ferdyn-Grygierek, A. Baranowski / Energy and Buildings 92 (2015) 45–54

10

15

20

25

30

35

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pera

ture

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Date

simulation

mea surement

10

15

20

25

30

35

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Date

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measurement

Fig. 11. Comparison of average daily values of measured and calculated indoor temperature in the period from June to August for two selected zones: Flora&Fauna hall (left),Ethnography hall (right).

Table 3Percentage differences of average daily values of indoor temperature for four zones (measurement–simulation).

Zone Relative difference (%) Correlation factor The share of the time when thedifference is less than 10% (%)

The share of the time when thedifference is less than 5% (%)

Ethnography −4.8–5.8 0.981 100 96.1Flora&Fauna −3.3–8.8 0.980 100 90.9Temporary exhibition −3.8–3.8 0.986 100 100Corridor on the 1st floor −2.0–9.0 0.964 100 89.6

0

4

8

12

16

20

24

28

32

0 1b 2 3

Mon

thly

hea

t dem

and,

kW

h/m

2

Case

a)Qinf

Qtot -Qinf

0

4

8

12

16

20

24

28

32

0 1b 2 3

Mon

thly

hea

t dem

and,

kW

h/m

2

Case

b)Qinf

Qtot -Qinf

0

4

8

12

16

20

24

28

32

0 1b 2 3

Mon

thly

hea

t dem

and,

kW

h/m

2

Case

c)Qinf

Qtot -Qinf

0

4

8

12

16

20

24

28

32

0 1b 2 3

Mon

thly

hea

t dem

and,

kW

h /m

2

Case

d)Qinf

Qtot -Qinf

Fig. 12. Monthly (February) heat demand (Qtot—total heat demand, Qinf—heat for infiltration), (a) Flora&Fauna exhibition (1st floor), (b) Temporary exhibition (1st floor), (c)Ethnography exhibition (2nd floor), (d) Gallery of Painting (3rd floor).

J. Ferdyn-Grygierek, A. Baranowski / Energy and Buildings 92 (2015) 45–54 53

0%

20%

40%

60%

80%

100%

120%

140%

Flora&Fa una Temporary Et hnography Ga llery of Painting

Perc

enta

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crea

se o

f the

rmal

pow

er

Exhibition roo m

case 1b case 2 case 3

0%

20%

40%

60%

80%

100%

120%

140%

Flora&Fa una Temporary Et hnograp hy Ga llery of Painting

Perc

enta

ge in

crea

se o

f the

rmal

pow

er

Exhibition roo m

case 1b case 2 case 3

Fig. 13. Average increase (in relation to the case 0) of average daily thermal power in February (left) and April (right).

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Flora&Fa una Temporary Et hnography Ga llery of Painting

Qin

f/Qto

t

Exhibition roo m

case 0 case 1b case 2 case 3

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Flora&Fa una Temporary Et hnograp hy Ga llery of Painting

Qin

f/Qto

t

case 0 case 1b case 2 case 3

Fig. 14. Share of heat for infiltration (Qinf) in total monthly h

Table 4Monthly heat demand (total and for infiltration) for different variants of ventilation(the whole building).

Case February April

Total heat demand Infiltration Total heat demand Infiltration

MW h

0 34.13 1.80 8.87 5.591b 44.38 12.06 13.99 5.41

vri

5

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ui

ager.

2 43.69 11.37 11.78 3.153 39.37 7.05 13.73 5.14

entilation, despite infiltration raise, can be observed. This is theesult of a flow of the air, whose temperature is higher than thenside the building, to the museum rooms in some days of a month.

. Conclusions

Museum is a specific facility, which must meet very rigorousequirements regarding indoor microclimate. On one hand, it pro-ides proper conditions for stored and collected exhibits, and onhe other hand it meets expectations for thermal comfort of peo-le working and visiting it. The adequate air exchange is the key tobtain and maintain the desired parameters of indoor climate.

The studies refer to one specific museum, yet they do shownfortunately not uncommon problem related the museum build-

ngs modernization which were carried out improperly. This

Exhibition roo m

eat demand (Qtot) in February (left) and April (right).

concerns the situations when the cooling system was implementedin particular halls, but the ventilation system ignored.

The performed simulations revealed that the ventilation in theexamined museum is insufficient. As a matter of fact, air infiltra-tion occurs only on the first floor. The flow of air infiltration in thewinter season at low outdoor temperature is at the medium level of0.3 h−1. In warmer periods of the year it does not exceed 0.2 h−1 onaverage. Infiltration on the remaining floors is very small and theventilation of these halls in larger part takes place mainly with thestale air from the staircase. The ventilation air flow in the buildingis possible thanks to the open construction of the staircase (atriumkind), where the stack effect occurs. This way of ventilation is insuf-ficient from the point of view of hygiene and the requirements ofexhibits’ protection. The average air exchange throughout the yearin individual rooms ranges from 0.04 to 0.15 h−1. Maximum valuesslightly exceed 0.4 h−1, yet only in the winter in one exhibition hall(Flora&Fauna exhibition on the first floor). It is of vital importanceto improve the ventilation system in the museum.

Total modernization of ventilation systems in the museumbuildings can pose a great challenge for designers due to the historicnature of these buildings. The acceptable solution is to use supply-exhaust ventilation in the exhibition halls. However, this wouldrequire interference in the building structure, and also obtainingthe consent from the conservator-restorer and the building man-

Performed simulation analyses proved the use of the exhaust fanon the roof of the staircase to be a relatively simple way to improvethe ventilation. This method only slightly interferes in the structure

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4 J. Ferdyn-Grygierek, A. Baranowski

f the building and significantly improves the air exchange in theooms on all floors: in the analysed case mechanical exhaust of000 m3/h increases the air exchange fourfold. The advantage ofhis solution is also the alignment of the ventilation air flow ratehroughout the year.

Forcing greater air flow in the staircase (case 1) or directly inhe exhibition rooms (case 2) will result in the increase of air infil-ration through the windows in particular exhibition halls. The airxchange on upper floors increases. The satisfactory air exchangeevel (0.4 h−1) was obtained in the Ethnography hall and the Galleryf Painting.

The most balanced air exchange of the building can be obtainedy the use of the case 3 (combination of an exhaust through thetaircase’s roof with an air supply) in the case of the worst venti-ated rooms (the Ethnography room and the Gallery of Painting).he average air change rate in this variant is close to 0.5 h−1. Thedvantage of the use of mechanical ventilation system is provid-ng a stable amount of ventilation air during the whole year, whichannot be achieved with the use of natural ventilation system.

The simulations also showed that the change of ventilation sys-em will generate changes in thermal needs of the building. Theverage monthly increase in heat demand differs due to used ven-ilation system. In cold February total heat demand of the buildingncreases by about 30% in the case of using exhaust ventilation sys-ems, and in the case of using supply and exhaust ventilation systemeduced by about 15%.

Among the proposed ventilation systems the least energy-ntensive is the case 3, which is also preferred on account ofmproving air exchange. The case 1 is easier to implement (exhaustan on the staircase). The case 3 is economical; however, it requires

ore investment outlay and presents problems due to the need forhe installation of air supply fans in the exhibition rooms.

The studies confirmed that the methods of numerical simulationupported by measurement validation are a proper tool for the anal-ses and the search for optimal solutions for ventilation of buildingsf a complex internal structure. The performance of a series ofariant simulations carried out for different ventilation systemsill be a basis for making investment decisions by the buildinganager.

cknowledgment

The work was supported by Polish Ministry of Science andigher Education within research grant N N523 448136.

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