Indoor fountains and enclosed spaces

Indoor fountains and enclosed spaces

Coordination of architecture, humidity, sound, sealing and operation

An indoor fountain can become the focal point of a business center, lobby, or meeting space. Water movement, surface texture and lighting form part of the experience of being in the building; But the quality of this experience depends on the daily performance of the collection. Improper humidity, annoying noise, splashes on the walkway or difficulty in cleaning can reduce the value of the design.

In this chapter, a hypothetical water wall is examined to clarify the relationship between fountain design and building architecture. The numbers are educational assumptions and are not specifications of an actual GSO product or project. Executive design should be completed with selected equipment, building conditions and sample testing.

49–1. User definition and performance criteria

For the present example, a water wall is considered in the pause space of the commercial center. Users pass in front of it or sit at a certain distance. Contacting and playing with water is not part of the set's usage.

The description of the project needs should go beyond the external dimensions and determine the following:

• the area that must remain dry during activity;

• Acceptable humidity and temperature conditions of the adjacent space;

• Acoustic criteria in the seating area and nearby commercial units;

• Operating hours and status outside operating hours;

• cleaning method, parts replacement and water quality control;

• Assembly response to leaks, power outages or ventilation disruptions.

These criteria must be specified before the final selection of materials and equipment; Because changing the texture of the wall or the shape of the water impact can affect the appearance, sound and splashing at the same time.

49–2. Choosing the shape of water movement

In the interior, several options can be considered:

For this study, the water flow on the wall surface is chosen.

In the introduction of Aryaval, GSO explains the movement of water on a textured surface and the possibility of creating different fall patterns. Choosing a texture for an interior project should be done along with sound and splash checks. Aryavall wall fountain GSO ^[322]

In contrast, Aquatique Show's Aquavision product is an example of a closed circulation free fall curtain. The performance details of these two types should not be assumed to be the same. Introducing Aquavision ^[323]

49–3. Educational sample specifications

Pond width, water depth and discharge per width unit are the starting assumptions of the study. Neither alone is a general criterion for the design or verification of spray control.

The surface of the wall must allow access to the upper sections, distributors and hidden connections. A design that requires extensive cover demolition to replace a small part increases maintenance costs.

Figure note from the source manuscript

Figure 49-1: Cross-section of coordination of architecture and facilities

Quarter wall, upper distributor, lower basin, sealing layer, service access road and public passage area are shown. The location of the air valves should also be included so that their relationship with the water level can be checked.

49–4. Flow calculation and water distribution

Assuming a flow rate of 0.4 liters per second for each meter of width:

$Q=6\times 0.4=2.4L/s$

$Q=2.4\times 3.6=8.64m^3/h$

This value should be tested with a real sample of the surface and distributor. The required flow rate depends on the slope, roughness, shape of the texture, the state of the joints and the behavior of water on the materials.

In order to control the distribution, in this study, three sections of two meters are considered. Assumed discharge of each section:

$Q_{section}=2\times 0.4=0.8L/s$

Dividing the circuit into adjustable sections allows balance; But the final uniformity will still depend on the alignment and geometry of the distributor.

Before the complete construction, a sample with real materials and details should be tested in several flows. The test result should indicate the range within which the desired surface is wetted and no splash or inappropriate noise is produced.

49–5. Estimation of pump head and power

For the training calculation, the head components are assumed as follows:

With a hypothetical total return of 0.50:

$P_{electric}=\frac{\rho gQH}{\eta }$

$P_{electric}=\frac{1000\times 9.81\times (8.64/3600)\times 7.5}{0.50}\approx 353W$

So the estimated input power of the pump at the hypothetical working point is about 0.35 kW.

This number is not the absolute nominal power of the engine. Pump curve, adjustment range, suction condition and filter drop change should be checked. Also, lighting, control and water management equipment are not included in this amount.

49–6. Water volume and return acceptance after blackout

The geometric volume of pond water in the activity mode:

$V_{basin}=6\times 0.8\times 0.35=1.68m^3$

We assume that after the pump stops, 0.12 cubic meters of water will return to the pond from the pipes and the distribution system.

For educational estimation of the water on the wall, we consider an average thickness equal to one millimeter:

$V_{surface}=24\times 0.001=0.024m^3$

This thickness is not a definitive characteristic of the actual flow and must be corrected by testing.

Assumed return volume:

$V_{return}=0.12+0.024=0.144m^3$

Acceptance capacity at a height of six centimeters above the activity level:

$V_{acceptance}=6\times 0.8\times 0.06=0.288m^3$

Increase in water level due to return:

$\Delta h=\frac{0.144}{6\times 0.8}=0.03m$

In this simple model, the water level increases three centimeters. The volume of the equipment inside the pond, its actual shape, compensating water cutoff delay, and other error modes still need to be considered. The reception area is also not the same as the final free distance to the edge of the pond.

Figure note from the source manuscript

Figure 49-2: Pond levels

Activity level, hypothetical three-centimeter rise after stopping, six-centimeter acceptance range, warning level, and final edge are displayed. It should be emphasized in the subtitle that the executive levels are determined after measuring the return water.

49–7. Sealing and limiting the consequences of leakage

In the internal fountain, the sealing must be designed as a continuous system. The final surface of the stone or tile alone is not considered as a sealing layer.

In the detail plan, the connection of the wall to the basin, the passage of pipes and cables, movement joints and the place of connection of parts should be specified. The choice of materials should also be compatible with water, materials used in maintenance and possible movement of the infrastructure.

For the present example, the following predictions are suggested:

• The possibility of viewing or monitoring hidden parts prone to leakage;

• leak sensor in the right place;

• Automatic shut-off of compensatory water in the event of an error;

• Specific service evacuation route;

• Access to connections without extensive destruction.

Autofill should not hide leaks. Recording the volume of compensated water and warning of abnormal consumption can help early detection of the problem.

49–8. Structural load of pond and wall

The water mass of the pond in the active state, with an assumed density of 1,000 kg/m3:

$m_{water}=1.68\times 1000=1680kg$

This value is only the mass of water. The weight of the pond, infrastructure, wall covering, pump, equipment and maintenance load should be added to it.

To understand the order of load, the weight of water divided by the surface area of the pond:

$q_{water}=\frac{1680\times 9.81}{6\times 0.8}\approx 3434N/m^2$

That is, about 3.43 kPa, only for water at a depth of 35 cm.

This simple division does not determine the actual reaction of the supports. If the basin is placed on a foundation or chassis, the load can be transferred centrally or linearly to the building structure. The control of the structure should be based on the actual path of load transfer and the highest possible water level.

49–9. Estimation of evaporation and latent load

An indoor fountain is a source of water vapor production. The amount of evaporation depends on air temperature, humidity, air speed, wet surface and the way water moves. The area of ​​the wall alone is not enough to determine it.

In terms of building humidity management, ASHRAE bases its assessment on the balance of production, transfer and removal of water vapor. Building humidity management in ASHRAE ^[324]

To continue the example, we assume a total evaporation rate of 1.2 kg/h. This value should be replaced by a valid calculation or sample test.

With an approximate latent heat of 2450 kJ/kg:

${\dot{Q}}_{latent}=\frac{{\dot{m}}_{evap}{h}_{fg}}{3600}$

${\dot{Q}}_{latent}=\frac{1.2\times 2450}{3600}\approx 0.82kW$

This value is the latent charge corresponding to the hypothetical evaporation; The power consumption of the dehumidifier is not. The actual humidity control energy will depend on the ventilation system and its working conditions. The effect of evaporation on water temperature and thermal balance of the space should also be investigated.

49–10. The balance of moisture and air required

Let's assume that the humidity ratio of the incoming air to the investigated space is equal to:

$w_{supply}=0.008kg/k{g}_{dryair}$

and the target humidity ratio of the outlet air:

$w_{room}=0.010kg/k{g}_{dryair}$

These values are the mass of water vapor to the mass of dry air and are not relative humidity percentages.

For the simple steady state, assuming complete mixing and considering only the moisture load of the fountain:

${\dot{m}}_{dryair}=\frac{{\dot{m}}_{evap}}{w_{room}-w_{supply}}$

${\dot{m}}_{dryair}=\frac{1.2}{0.010-0.008}=600kg/h$

With an assumed specific volume of 0.83 cubic meters per kilogram of dry air:

$\dot{V}=600\times 0.83=498m^3/h$

So, in these hypothetical conditions, about 500 cubic meters per hour of prepared air with specific humidity can compensate the desired load in a simple balance.

This number is not the final building ventilation flow rate or fresh air requirement. People load, air infiltration, other moisture sources and air distribution should be added. If the intake air is not dry enough, increasing the flow alone will not solve the problem.

49–11. Placement of valves and condensate control

Throwing air directly onto the water surface can change the flow and splash pattern. Therefore, the position of the valves should be checked with a practical example of the fountain.

At the same time, moisture should not be trapped in cavities behind walls or near cold surfaces. The condensation assessment should compare the surface temperature and the dew point of the surrounding air; Measuring the humidity in the center of the hall alone does not show the condition behind the cover.

In the sample plan, the monitoring points include the adjacent public space and the service area behind the fountain. The sensor location must be protected from direct wetting and representative of the conditions under investigation.

The control logic should also specify that the fountain will reduce or stop functioning in the event of ventilation failure or moisture leaving the approved limits.

Figure note from the source manuscript

Figure 49-3: connection plan of fountain and ventilation

Prepared air path, return air, water level, the space behind the wall and the location of the sensors are displayed. The straight arrow of the air to the water wall is specified as the condition to be checked in the test.

49–12. Sound and vibration

The sound of the fountain is formed by the impact of water, the flow in the pond and the mechanical equipment. In indoor space, reflection from glass, stone and ceiling also affects the result.

For example, suppose at one point:

• Background sound level: 48 dB with A weighting;

• Hypothetical independent contribution of the fountain: 45 dB with A weighting.

For two independent sources, the sum of sound energy is done logarithmically:

$L_{total}=10{\log }_{10}(10^{48/10}+10^{45/10})\approx 49.8dBA$

This result shows that the decibel numbers do not combine with the arithmetic sum. Basics of sound and addition of levels from CCOHS ^[325]

Example numbers are not an authorized audio benchmark for a project. In addition to overall alignment, the presence of monotonous engine noise, knocks, vibrations, or chatter should be checked.

In the present example, the place where the water hits, the installation of the pump, and the path of connecting the pipe to the structure are the three main points for sound and vibration control.

49–13. Water quality management and cleanliness

An indoor decorative fountain requires a specific water management plan. The CDC emphasizes that decorative fountains produce water droplets and that sediment, biofilm, temperature, water retention, and residual disinfectant are important in Legionella control. CDC Guidelines for Decorative Fountains ^[326]

For the sample project, the operation plan should specify the person responsible for monitoring, the parameters, the action limits, the cleaning procedure, and the conditions for reopening after shutdown. Wall surface, top distributor and hidden parts must be cleanable.

Clarity of water or absence of odor is not a substitute for defined controls. Also, the activity of the water fountain during the opening hours of the commercial center should not be the only basis for the circulation and water management plan.

Maintenance materials must be compatible with materials and equipment. The place of their storage and consumption should also be separated from the public space and accessible to responsible employees.

49–14. Control integrated with the building

Each condition should be documented with the cause, outputs affected, and method of return to service. For example, stopping the pump alone will not prevent water from entering through a faulty relief valve.

Communication with the building management system should convey the necessary information, but the necessary protections should not depend solely on operator observation of the alarm.

49–15. Delivery test in real conditions

The acceptance test must be done with the final materials and the activity of the building facilities.

A short test in an empty building does not represent all operating conditions. Initial acceptance must be completed by recording performance in selected work conditions.

Figure note from the source manuscript

Figure 49-4: The test document from the company's archive

Select an image of flow uniformity control and an image of humidity or noise measurement. The name of the project, the measurement point and the working status of the fountain should be included in the subtitle.

49–16. Study results and exploitation file

Before implementation, the required surface flow rate, evaporation rate, acoustic performance and spray control should be corrected with valid data or sample testing. The design of the structure, electricity, sealing and ventilation must also be coordinated with each other.

The delivery file should include final settings, as-built drawings, permissible work limits, cleaning instructions and test results. These documents allow the fountain to maintain its visual quality during operation and to remain compatible with the conditions of the building's internal environment.