31148/1998

In the Huurre Ski Tunnel in Finland,optimal conditions are always guaran-

t e e d. Va i sala transmitters play an impor-tant role at this indoor ski track, continu-ously measuring the prevailing humidity,

temperature and carbon dioxide levels.

he Vuokatti Ski Tr a i n-ing Center is locatedin central Finland.S kiers from all over

the world come here to train –even in the summer time. Th emain attraction is the 1.2 kmS ki Tu n n e l, which has a 2.4 kmnatural snow surface ski track.With curving trails and hills, theconditions are similar to natu-ral outdoor ski trails in every re-s p e c t.

Winter conditionsg u a r a n t e e d

The winter weather conditionsin the tunnel are optimal –there is snow and fresh air, butit is not too cold. Because theconditions are stable, weather-related risks and inconv e n-iences are not a factor. Anadvanced ventilation systemprovides humidity control andgood air quality. Humidity,temperature and carbon diox-ide levels are measured with

The NuAire Group produces

one of the world’s widest ranges

of ventilation fans and eq u i p-

m e n t, from domestic bathroom

and toilet extract fans to large

c o m m e r c i a l / i n d u s t rial units. Th e

company is also a mark e t

l eader in condensation control

equipment for public housing,

and has dev e l o p ed an industry

l eading range of ventilation con-

trols for the commercial sec t o r.

NuAire currently has customers

in over 25 countries worl d w i d e .

Lo c a t ed in Caerphilly, South

Wa l e s, United Kingdom, NuAire

has about 300 employees.

Hanne Österberg, BB A, B. S c. (C o m p. )M a r keting AssistantSensor Systems DivisionVa i sala HelsinkiF i n l a n d

N e ve r -Ending Wi n t e rStability minimizes the need forcalibration and maintenance,helping to reduce the total op-erating costs of the system.

The fan action is directly con-trolled by the sensors. When theo c c u p a n cy sensor detects peo-ple in the room and the carbondioxide level starts rising, thefan switches on, supplying theright amount of fresh air to ther o o m. This prevents the roomsfrom becoming stuffy and pro-vides healthier conditions forthe occupants. Since the fan isused only when needed, thiseliminates excess energy con-s u m p t i o n.

NuAire’s experiences withVa i sala instruments have beeng o o d. So far, we have installedten systems with Va i sala sen-s o r s, and they have measuredup to our expectations. All thetransmitters are working fine.

The Ski Tunnel has attracted skiers from all over the wo r l d.

The housing of HMP 140 tra n s m i t t e rs provides IP65 protection

from dust and sprayed water, so these are suitable instruments for

humid spaces and outdoor installations.

■

T

32 148/1998

Va i sala transmitters. The mainmeasurements are taken insidethe tunnel and from the inletand exhaust air of the refrigera-tion units. HMP 142 humiditytransmitters and GMD20 CO2transmitters are used to meas-ure humidity, temperature andcarbon dioxide in the ventila-tion ducts, while HMP 14 3transmitters measure the humid-ity and temperature of the snow.

M r. Ve sa -Pe kka Sarparanta,Executive Director of the HuurreS ki Tu n n e l, came up with theidea of the tunnel in the 19 8 0 s,when he was a trainer for theFinnish national cross countrys kiing team. “There was a clearneed for stable training condi-tions for competition ski e r s. Inthe summer, these conditionscan only be found at high alti-tudes – for example on glaciersat 1900 m. These are not goodtraining conditions, however,because they require daily trav-el and altitude adjustment. ”

After he saw snow making inl a b o r a t o ry conditions in Italy,M r. Sarparanta put his plans inm o t i o n. Construction of thehighly innovative Ski Tu n n e lb e gan in April 19 97 and was com-pleted in eight months.

Unique refrigerationsystem

Sabroe Finland Oy, a companywith extensive experience inrefrigeration tech n i q u e s, was incharge of the planning andimplementation of the refrigera-tion system for the Ski Tu n-n e l. Mr. Marko Matka v u o r i,Electrical Engineer from theSabroe project team, commentson the start of the project: “Werealized early in the planningstage that there would be somedifficult measuring points be-cause of the discrepant condi-tions caused by snow maki n gand other factors. We decidedon Va i sala’s measuring equip-ment at this time, based on its re-cognized quality and Va i sa l a ’ sgood technical support. ”

The air and snow tempera-ture and the air-conditioning inthe tunnel are monitored andcontrolled by computer tech-n o l o g y. The inside air andsnow temperatures are normal-ly between -5 and -9 °C, butcan be dropped to -18 °C ifneeded; even ice formation ispossible. The tunnel air is com-pletely exchanged every fourh o u r s. The snow making sys-tem consists of high pressurecannons that replenish the trails u rface at night when required,normally every two weeks.

The ventilation is controlledby measuring the carbon diox-ide levels so the amount offresh and exhaust air alwayscorresponds to actual demand.

Schematic drawing of the tunnel sys t e m.

This avoids any unnecessa ryload on the refrigeration sys-tem when there are no activ-ities in the tunnel.

Four machine rooms, eachwith a ventilation machine andtwo separate refrigerators con-taining a compressor and anexpansion coil, provide refrig-eration and ventilation. Th erooms are located above groundmore than 300 meters apart. Th em a chine rooms have program-mable controllers connected tothe Wi n d o w s -based monitor-ing program in the controlr o o m. These are wired with anRS485 bus. The system can beremote accessed and programmedthrough a modem in the mon-itoring computer. All Va i sa l a

transmitters are connected tothis system. The output datafrom the transmitters is fed tothe monitoring program fromw h i ch all settings, includingthe desired temperature, can bea l t e r e d.

Sabroe’s initial plans for thetunnel’s refrigeration systemhave been a success. Mr. Sarpa-ranta does see some futurech a l l e n g e s, however, as far asoptimization of the system isc o n c e r n e d. The relative humid-ity in the tunnel is normallybetween 85–95% RH.According to Ve sa -Pe kka Sarpa-ranta: “One possibility wouldbe to lower the humidity toaround 80% RH. No evapora-tion would take place at thispoint – so the snow itselfwould act as ‘a polar radiator’.Control of the humidity equi-librium in general is anotherkey issue.” The greatest sourcesof humidity peaks are snowm a king and the fresh air that isintroduced into the tunnel.

Landscaping is a future proj-e c t. Plans call for the tunnel tobe protected and concealed bya layer of soil, after which it will

Ve s a -Pekka Sa r pa ranta ha s

been pleased by the

international interest and

welcomes visitors to the Ski

T u n n e l.

33148/1998

GML20T and GMD20D

New CO2 Pro d u c t sComplement theGM20 Se r i e s

Two new productshave been added toVa i sala’s carbon diox-ide CA RBOCA P

®

transmitter series.When installed in theGM W 21 transmitter,the new GML 2 0 Tmodule makes it pos-sible to measure tem-perature in addition tocarbon dioxide levels.L i ke the previouslyl a u n ched GML 2 0module, the GML 2 0 Tis also compatiblewith LonWo r ks

®.

he GMD20D is adisplay version ofthe GMD20 ductm o u n t carbon diox-

ide transmitter. In Va i sa l a ’ sduct mount transmitters, thesensor head is inside the venti-lation duct. The display coveris especially useful for specialapplications and during calibra-tion ch e cks, for example.GMD 2 0 /D transmitters aresmall in size, and they offeroutstanding performance andv e r sa t i l i t y.

The GM20 series of carbondioxide transmitters is kn o w nfor its superior stability. Com-bined with the interoperabilityof LonWo r ks®, the result is ac o s t -effective, flexible and reli-able solution for buildingautomation systems.

The GML20T module, which is

installed inside the GMW21

t ra n s m i t t e r, enables carbo n

d i oxide and tempera t u r e

m e a s u r e m e n t s.

The duct mountable

t ransmitter GMD 2 0 D

with a digital display.

look much like a naturally occur-ring ridge.

A winter wonderland

The main purpose of the SkiTunnel is to provide facilitiesfor cross country skiing for bothcompetitors and fitness trainerswhen there is no snow outdoors.The tunnel is also ideal for test-ing cold-weather phenomenaand equipment in winter con-d i t i o n s. For companies whoseoperations and products areconnected to winter, includingmanufacturers of clothing, ski sand ski waxes, for example, it isan excellent facility for productdevelopment and testing. Otheractivities include medical stud-ies connected to exertion asth-ma or exposure to cold, as wellas industrial tests (of car tires,for example).

Tourists are another targetg r o u p. Mr. Sarparanta has beengratified by the international in-terest in the tunnel, which hasattracted some 20,000 visitorsfrom 40 countries. He expectsto see more ski tunnels in fu-ture. “After all,” he sa y s, “theyare based on the same principleas indoor swimming pools. ”

Ve sa -Pe kka Sarparanta has astrong background in bothengineering and Finland’s sport sscene, as well as a fascinationwith new ideas. In the past, hewas head trainer for Finland’scross country skiing team anddirector of the Vuokatti Ski Tr a i n-ing Center, which has been inexistence for 50 years and isFinland’s third largest sport sc e n t e r.

“ Va i sala has long experiencein measurement techniques andstrong kn o w -how – their trans-mitters have been a reliablechoice for us,” says Mr. Sarparantasumming up his experience withVa i sa l a. ■ ■

T