# Usage cost calculation

## Content general rules of thumb

• Location of the door – adapting to the climate
• Direction of movement of the door
• Door size
• Some mixed rules of thumb and experience

Under each heading, first follow a summary and then a more detailed description. If you want a quick walkthrough, concentrate on the summary panes.

## Location of the door-adapting to the climate

The location of the door should of course primarily be subordinated to the traffic to, from and in the building.
“The door is primarily part of the company’s transport system and in the second place part of the building” (Door manual, message No. 80)

Much is won by avoiding getting doors in to the corners of the building. The wind conditions are usually most difficult.
The best door location is in the middle of the building, preferably on the lee side of other buildings, mountains etc. This avoids unnecessary wind loads
and in addition, it will be less cold air into the premises when the door is opened. However, if the door must be positioned near a corner, a simpler windproof shielding can be an important measure.

## Direction of movement of the door

Summary

• Side-going doors have fewer collisions incidents
• If the door is used in high frequency, it should be side ward going

Human stereoscopic vision allows you to assess distances, depth and width ratios. Man is also made to primarily move in the horizontal plane. This is why the eyes sit in horizontally and not vertically.

When it comes to assessing the depth, width and height (for example, of a doorway to pass), it is the case that the direct vision in the widening is about 34 ° while the direct vision in height is only about 2 °. This is, of course, because the eyes are positioned in a widening joint and thus give better stereoscopic vision in that joint.

This is the natural explanation for side-going doors cope better from collisions. It looks better in depth-width-led and simply makes a safer assessment sideways.

A comparison is the “flagpole example”;
If you ask a group of people to guess the height of a flagpole, most of them pretty badly guesses. But if you put the flagpole down on the ground, they guess most pretty right.

Starting from the above, the rule of thumb is:

If the is used with high frequency, it should be side wards moving.

Given the recent decades (perhaps exaggerated) popularity of the upward gates, one can wonder how to “look” at the fact that a collision costs at least 10.000 SEK incl. assembly per time. Two collisions and it has cost more than the door cost to buy. This example shows that perhaps you should “look a bit more on the width” before determining the direction of movement of the door.

## Optimizing Door Size

Door size is not quite obvious. Avoid larger doors than necessary.

Estimate 40 – 60 cm of space on each side of the widest transport. Estimate 15-25 cm above the maximum transport. Smaller spaces increase the risk of collision. If the door is located in a slope, take into account the extra need for space in height due to inclined transport.

Avoid larger doors than necessary. At such a low usage as 8 times/day, an excessive door opening corresponds to an energy loss of approximately 600 kWh/year per increased square meter of door than necessary.

## Mixed rules of thumb and experience

Dimensioning
The sizing is not only to withstand wind loads – it’s just as much for the door’s own durability.

Seals
Pinching seals are preferable to sliding.

Electrically operation
If the door is motorized and is used in high-frequency, it should be side ward going. See also Passage frequency below.

Movement speed
The most favorable opening/closing time is normally about 12 sec (Door Manual). However, for high traffic openings, the speed of opening/closing time can be lowered to about 7 sec. Shorter movement speed increases the risk of collisions and injuries, and the door could open to early and thus increasing (instead of reducing) energy loss.

Door movement
Man’s way of seeing, i.e. the side-oriented vision of the eye and the view is the natural explanation of why side ward moving door should be chosen when the passing frequency is high. This is also an explanation of why overhead sectional door are more often hit.

Opening time
A 4 x 4 m door (16m2) that is passed 5 times per hour, costs hundreds of SEK per year unnecessarily for every second of extra open time. If the opening hours are reduced by a number of seconds, one can thus save several thousand SEK per year. (Depends of course on where the door is located, etc.)

Passage frequency

1. The rule of thumb that a electrically operated door pays off if the passage frequency 8 times per day is “cautious”. Already at about 4 passages per day, a electrically operated door pays off.
2. If the door is used with low frequency, special insulation and tightness requirements should be set.
3. If the door is spring-balanced, it should be ordered with stronger springs if the door is to be used more than 4 times/day.

Standard or special solution
In the long term, standard solutions are cheaper in service and spare parts.

Capital cost
Every penny invested in user cost quality, usually has a short pay-off time. This is basically the entire Door Handbook’s moral: that the cost of capital is only a small part of the total usage cost of a door.