Tag Archives: lifehack

Chair material should be breathable

Strangely enough, fancy office chairs are often upholstered in leather or other non-breathable material. After an hour or so, sitting in them gets uncomfortable because the moisture does not evaporate from the skin that is separated from the chair only by some cloth. However, people usually sit in office chairs for hours at a time, and I doubt that the chairs are designed to deliberately provide some discomfort to encourage users to occasionally stand up for health reasons. Especially in a hot climate when the air conditioning may break down or just be too weak, a breathable chair would make much more sense. Making a mesh chair is simple: stretch a breathable fabric on the chair frame. The small holes in the fabric let moisture evaporate from the surface. A mesh chair is probably cheaper to manufacture than a leather-upholstered one.

A reason for using leather may be to signal wealth by using a material associated with expensiveness.

Modern synthetic meshes are as durable as leather for practical purposes, because sitting in a chair is not a high-wear use.

Eggs boiled in an oatmeal cooker

1 Reply

In addition to rice cookers, multi-cookers and egg boilers, there are devices specifically for cooking oatmeal, even though a rice cooker would do the job just fine. Perhaps the reason is that the minimal cooking time is shorter for oatmeal than for rice, so an oatmeal cooker speeds up the process compared to a non-programmable rice cooker. A programmable one could of course be set for the shorter cooking time.

The normal cycle length of rice cookers (30-45 min) and oatmeal cookers (20 min) is longer than the 12-15 minutes it takes to hard-boil eggs. However, overcooking a hard-boiled egg does not worsen its taste or texture significantly in my opinion, unlike for meat or vegetables. It turns out that oatmeal does not stick to eggshells that much, so eggs boiled in a cooker together with the oatmeal can be rinsed off quite easily.

Boiling the eggs and oatmeal together saves either time (if there is only one device available for cooking) or the labour of washing one more cooker (when using separate ones for eggs and oatmeal). Even with a dishwasher, disassembling a cooker, putting it in and taking it out of the washer and reassembling takes a few minutes. Rinsing the eggs is quicker.

Protecting a wound or burn that needs frequent access

Leave a reply

If it is necessary to put cream on a burn frequently, then a band-aid is inconvenient, because it must be pulled off every time. Also, a band-aid may stick to an oozing wound and reopen it every time it is pulled off. If the damaged skin needs covering, for example because the weather requires thick clothes, then one solution is to stick or tie a small cup-shaped object on top of the wound. Tying is preferable, because removing a stuck object again irritates the damaged area. The edges of the cup should be soft, because these press on the skin (so a plastic bottle cap is a bad idea). One soft-edged approximately cup-shaped object is the eyepiece of swimming goggles.

Swimming goggles protecting wound

The eyepiece is nicely attached to adjustable straps for tying it on with neither too much nor too little pressure. The eyepiece may be flipped over to the side to get access to the damaged skin.

Of course, the location of the wound may cause difficulties in tying swimming goggles on top of it, e.g. on the torso. Even on the arm or the leg, the lengthwise movement of the sleeve or pant leg may push the goggles off, because the strap running around the limb does not resist lengthwise movement well. Then adding some bandages may be necessary.
Overnight, the area under the goggles gets sweaty. To avoid this, small air holes may be drilled in the eyepieces, which of course makes the goggles useless for swimming.

Improvements for hotels

Leave a reply

Commonly in hotels the room keycard has to be inserted into a slot for the lights in the room to turn on. An annoyance occurs when the lights are reset each time the card is removed and re-inserted, such as when leaving and re-entering the room (this problem and most of the subsequently mentioned ones are based on Courtyard by Marriott Chennai, but some are based on other hotels). Typically all the lights turn on and the unnecessary ones have to be turned off one by one. A simple and cheap microcomputer could remember the on-off settings of the lights and keep these until reset. Another similar problem is that the temperature of the AC or heating, as well as the fan speed, gets reset when the keycard is removed from the slot. Thus the AC has to be readjusted after each re-entry.

The keycard should work consistently, not require several attempts to operate the lift or open the room door.

It is a nice touch for a hotel to have a steam room, sauna or jacuzzi next to the fitness centre, but it would be even better if these were in working order and clean. Another nice touch is to provide slippers in the room, but if these are child-sized, then they are not very useful for an adult male. If there are two pairs of slippers in a room, then different-sized pairs would be reasonable and almost as cheap to provide as same-sized ones.

If (free) wifi is advertised, then it would be nice if it was working. Wifi problems can be detected automatically (by wifi-enabled devices placed in the corners of the hotel remotest from the routers) without waiting for annoyed guests to contact the front desk.

An electric kettle in the room is good for making tea, but placing glasses next to the kettle invites an absent-minded person to pour hot water into these, which cracks them.

The carpet should not shed hair that sticks to socks and anything else it comes into contact with (by floating in the air for example).

The fitness centres in hotels are typically less than 25 square metres. It is possible to choose machines and weights for a small room in such a way that cardio and all major muscle groups can be trained, but hotels seem to choose the machines randomly, e.g. three ellipticals and a stair stepper, but no rowing machine. Or two quadriceps training machines (leg extension and leg press), but no hamstring training machine (prone leg curl). This is despite the fact that quads are easy to train without a machine (do squats with or without weights), but hamstrings difficult.

A common problem in hotels is street noise in the room, which may be expensive to fix if the hotel construction quality is bad. One hotel in which the room was quiet despite a busy street outside was Sheraton New Delhi. A possible reason for its quietness was that the windows had two layers of packet glass, consisting of two or three layers each.

Hotel breakfasts should have a list of ingredients next to each dish, not just the name of the dish, especially when the name is unfamiliar to most visitors, e.g. the name is in the local language for a traditional ethnic dish. The list of ingredients would be especially helpful to people with food allergies, but the non-allergic would also benefit – it is easier to choose with more info. The ingredients in the list should be ordered, starting with the ones that constitute the largest percentage of the dish.

The arrangement of dishes at buffet meals should make it logistically convenient to get food, i.e. movement to and from the dishes should be unrestricted (no closely placed tables blocking the way) and similar foods should be located together. Sometimes hotels make strange food placement choices, for example I have seen soups and meat dishes alternate. Rydges on Swanston in Melbourne placed all the dishes in a small recess off the dining area, so there was a traffic jam of people trying to get into and out of that nook with their plates.

Made-to-order (live cooking) dishes at buffet meals could be prepared and distributed faster if their order system was computerised and the eaters could order the dishes from their smartphones. Peak demand time can be predicted and the cooking started in advance to speed up the delivery of the dishes. Such just-in-time production has economies of scale, so is especially easy for larger buffets.

The hotel room logistics are often strange, e.g. a narrow corridor leading from the door to the room, with wardrobes built into the side of the corridor. The doors of said wardrobes open outward, blocking the corridor. On the other hand, in the Chennai Marriott bathroom the shower stall and the the toilet were behind the same sliding door. To access the toilet, the door had to slide in front of the shower, and to access the shower, the door closed off the toilet. This would be annoying if two or more people stayed in that suite and tried to use the shower and toilet simultaneously, because both could not be behind a closed door at the same time.

Another logistical problem in both hotels and apartments is a toilet door that opens inward. When the toilet is small, the door almost hits the pot, making it difficult to maneuver around the door for entry and exit. Some toilets are so tiny that when sitting on the pot, the knees touch the opposite wall. In this case, it would be better to place the pot diagonally so the knees fit in a corner.

Two doors at the ends of a short corridor that both open into the corridor are impossible to open at the same time, which lengthens the time of passing through both doors.

Some hotels want to show how modern they are by replacing light switches with small touchscreens with LED backlighting. The little LED lights are numerous enough to somewhat light up the room when the ceiling and other lights are turned off. For sleeping, it would be good to be able to turn off the LED lights of the touchscreens.

If a motion detector turns on the light, then being able to switch off the motion detector and the light would be preferable. Sometimes the light is unnecessary, such as during the day with curtains open. The sudden bright light may also be annoying, for example when visiting the bathroom at night.

Hotel beds are usually short, so people over 180cm have their feet over the edge, unless they lie diagonally. Luckily hotel beds are usually wide, so their diagonal is significantly longer than the long side.

Saving ventilation cost by using the wind

2 Replies

Most large modern buildings have active ventilation built in, meaning that electric fans drive the air through the building. The airflow direction is usually fixed at construction time. However, if the wind happens to blow from the opposite direction to the ventilation flow, then the fans require extra energy to counter the wind. On the other hand, if the wind agrees with the airflow in the building, then the fans may not need to be run at all. To save electricity, a building could have a wind direction sensor (a weather vane) on the roof connected to a switch that reverses the ventilation fans, so that the fans always pump air in approximately the same direction as the wind. If the wind is strong enough, a wind speed sensor (a small windmill or windsock) on the roof could stop the ventilation fans altogether.
The tradeoff for this adaptive ventilation system is the initial fixed construction cost and the ongoing maintenance of the weather vane, windsock and controller of the fans. All the extra components of the system (relative to the current unidirectional ventilation) are cheap and robust, so the both the fixed cost and the maintenance should be negligible.
Current ventilation systems have differently shaped air inlets and outlets in the rooms, which suggests that the system requires a particular airflow direction. In this case, adaptive ventilation may be much more expensive than the current ones, because the ventilation shafts and air vents need to be doubled. To avoid the need to build twice as many shafts and vents, have just the air inlets and outlets of the whole building switch roles with the wind direction. The rest of the system can remain unidirectional when the valves from the building’s inlet and outlet to the rest of the system switch appropriately. The air inside the building can then move in the opposite direction of the wind some of the time. In this case, the electricity saving is only realised if the building is sufficiently airtight, which is the case for modern highrises that have unopenable windows. If the air is allowed to move through the building independently of the ventilation and the wind is opposite the airflow in the system, then the fans have to overcome the air pressure difference like in the current systems. This wastes electricity.

When to open windows to cool or warm a building

2 Replies

My uninsulated apartment building went from too cold to too hot in about a week, which is normal in Canberra. People have started to open the windows in the stairwell in addition to their apartment windows. The timing of the opening seems a bit misguided – people open the windows in the morning. During daytime, the air outside is warmer than the air inside the stairwell, but during the night the outside air is colder. To state the obvious: to cool down the building, open the windows for the night and close them for the day. Currently the opposite seems to happen, although I counter this trend by closing the windows in the morning when I notice them open.
In general, if you want the building cooler and the outside air is colder than the inside, then open the windows, but if the outside is warmer, then close them. If you want the building warmer and the outside air is colder than the inside, then close the windows, but if the outside is warmer, then open them. This could easily be automated with temperature sensors outside and inside the building connected to a thermostat and small electric motors opening and closing the windows. Such a system would save some of the heating and cooling costs of the building.
There may be non-temperature reasons to open and close the windows, for example to let smell out of the stairwell or to keep insects from coming in. The second reason is not relevant for my building, because all windows have bugscreens and the exterior doors have a gap an inch wide under them, which the insects can easily use to get in.

Tenancy Ending Checklist

Leave a reply

Before the final inspection:
Give or receive valid notice of ending tenancy in writing, resolve any dispute about this.
Confirm any arrangements for agent/landlord to access property in writing.
Schedule final inspection.
Disconnect all utilities connected in your name.
Calculate rent payable until end of tenancy and pay that amount.
Cancel direct debit if necessary.
Clean property as needed when compared to incoming condition report.
Arrange for carpet cleaning if necessary.
Remove any additions, alterations you have done to property.
Print 1) bond refund form, 2) move-in condition report (keep a copy), 3) filled or blank move-out condition report, 4) key receipt to take to final inspection. 5) Put the move-in photos and video on a laptop/other device or print them to take to final inspection.

On the day of final inspection or move-out day:
Take photos of meters (date stamped).
Take photos/videos of condition of property and do your own condition report.
Bring the required forms, photos and video to the final inspection. Attend final inspection.
Return keys and get a receipt or sign a photocopy.
Resolve any issues with condition of property.
Sign bond refund form and lodge with Office of Rental Bonds (you or the agent can do this).

Rigid skirt to prevent falls

Leave a reply

Falls are a major cause of hospitalisation in the elderly and people with impaired balance or strength. A fall may cause a vicious cycle: the bad experience leads to a fear of falling, which makes people avoid exercise. Not exercising leads to worse balance and muscle condition. Weakness and a lack of balance cause more falls.
To prevent falls, people should train their sense of balance and their stabilising muscles, but in a way that does not risk injury via falls during training. One device that would allow practising balance while preventing falling over is a rigid wide-flared skirt attached above a person’s centre of gravity (the attachment could be almost under the armpits). The hem of the skirt would be above the ground when the body is upright, but its edge would touch the ground if the body tilts too much in any direction. Support from the rigid skirt would then prevent further tipping in that direction. The lack of support in a central position (and for slight tilts around it) allows practising balance, for example by standing on one leg and trying to stay upright. The principle is the same as for helper wheels (training wheels) on childrens’ bicycles, which are off the ground while the bike is in a central position, but touch the road and stop too great a tilt to the side once the bike tips away from the centre. Other analogies to the rigid skirt are hands-free crutches pointing in all directions simultaneously, or a walking frame that surrounds the body, as opposed to being pushed in front.
The advantage of the skirt for fall prevention over crutches or a walking frame is that the skirt is hands-free. The advantage over a fixed training frame, or somewhat slack ropes tied to the upper body that also prevent a fall, is that the skirt moves with the person. This makes training easier by allowing walking and jogging.
The skirt can be home-made from many materials, such as tent poles or bamboo sticks tied or duct taped to a belt at the top and a hula hoop at the bottom. Using modern materials such as carbon fiber ski poles can make the skirt light, yet strong and rigid.
Of course the rigid skirt looks strange and attracts notice if not too many people are using it. On the one hand, the skirt does not have to be used in public if in-home training is enough. On the other hand, the first walking frame or the first crutches must also have looked strange to bystanders, but are now accepted mobility aids that almost nobody reacts negatively or even curiously to.
For using the skirt on the street, one problem is the wide-flared base (about 2m in diameter) that makes it difficult to pass other pedestrians. One (expensive) solution is to make the skirt out of sticks that can be moved independently and add a robotic controller that keeps the skirt narrow if the body is upright, but when the tilt angle becomes large enough, flares the skirt out in the direction of the tilt to stop the fall. Flaring the skirt means moving the sticks outward and lengthening them.

Heating my apartment with a gas stove

1 Reply

There is no built-in heating system in my Australian-standard un-insulated apartment, and the plug-in electric radiators do not have enough power to raise the temperature by a degree. In the past two winters, I used the gas stove as a heater. It is generally unwise to heat an enclosed space without purpose-built ventilation (such as a chimney) by burning something, because of the risk of CO poisoning. Even before CO becomes a problem, suffocation may occur because the CO2 concentration rises and oxygen concentration falls. Therefore, before deciding to heat with a gas stove, I looked up the research, made thorough calculations and checked them several times. I also bought a CO detector, tested it and placed it next to the gas stove. The ceiling has a smoke alarm permanently attached, but this only detects soot in the air, not gases like CO.
For the calculations, I looked up how much heat is produced by burning a cubic metre or kilogram of CH4 (natural gas), how much the temperature of the air in the apartment should rise as a result, how much CO2 the burning produces, and what the safe limits of long-term CO2 exposure are.
The energy content of CH4 is 37.2 MJ/m3, equivalently 50-55.5 MJ/kg. A pilot light of a water heater is estimated to produce 5.3 kWh/day = 20 MJ/day of heat, but a gas stove’s biggest burner turned fully on is estimated to produce 5-15 MJ/h, depending on the stove and the data source.
The chemical reaction of burning natural gas when oxygen is not a limiting factor is CH4 +2*O2 =CO2 +2*H2O. The molar masses of these gases are CH4=16 g/mol, O2=32 g/mol, CO2=44 g/mol, H2O=18 g/mol, air 29 g/mol. One stove burner on full for 1 hour uses about 0.182 kg =0.255 m3 of CH4 and 0.364 kg of O2, which depletes 1.82 kg = 1.52 m3 of air. The burning produces 2.75*0.182 = 0.5 kg = 0.41 m3 of CO2. The CO2 is denser than air, which is why it may remain in the apartment and displace air when the cracks around the windows are relatively high up. On the other hand, the CO2 also mixes with the air, so may escape at the same rate. Or alternatively, the CO2 is hot, so may rise and escape faster than air. For safety calculations, I want to use a conservative estimate, so assume that the CO2 remains in the apartment.
The volume of the apartment is 6x5x2.5 m =75 m^3. The density of air at room temperature is 1.2 kg/m^3, thus the mass of air in the apartment is 90 kg. The specific heat of air is 1005 kJ/(kg*K) at 20C. The walls and ceiling leak heat, thus more energy is actually needed to heat the apartment by a given amount than the calculation using only air shows. It takes 900 kJ of heat to raise the temperature of the air, not the walls, by 10C (from 12C to 22C). This requires 9/555 kg = 9/(16*555) kmol of CH4 with estimated energy density 55500 kJ/kg. Burning that CH4 also takes 9/(8*555) kmol of O2 and produces 9*11/(4*555) kmol = 9/200 kg of CO2.
The normal concentration of CO2 in outside air is 350-450 ppm. Estimate the baseline concentration in inside air to be 1/2000 ppm because of breathing and poor ventilation. Adding 1/2000 ppm from heating, the CO2 concentration reaches 1/1000 ppm. This is below the legal limit for long-term exposure.
CO is produced in low-oxygen burning. As long as the CO2 concentration in the air is low and the oxygen concentration high, the risk of CO poisoning is small.
For the actual heating, I first tested running the smallest burner all day while I was at home, and paid attention to whether I felt sleepy and whether the air in the apartment smelled more stale than outside or in the corridor. There seemed to be no problems. For nighttime heating, I started with the smallest burner in the lowest setting, similarly paying attention to whether the air in the morning smelled staler than usual and whether I felt any different. Because there were no problems, I gradually increased the heating from week to week. The maximum I reached was to turn on the largest burner to less than half power, and one or two smaller burners fully. Together, these burners produced much less heat than the largest burner on full, as could be easily checked by feel when standing next to the stove. At night, the stove prevented the temperature in the apartment from dropping by the usual 2C, but did not increase it. The CO2 produced was probably far less than the bound I calculated above by assuming a 10C increase in temperature. Empirically, I’m still alive after two winters of letting the gas stove run overnight.

Reducing reflections off eyeglasses

1 Reply

Spectacle shops try to sell customers more expensive lenses with glare-reducing coatings. Such coatings are often fragile, which benefits the sellers, because the glare-reducing lenses would need frequent replacement. Another way to reduce glare reflecting into the eye is to find its source and block it. For example, standard flat-lens eyeglasses reflect rays coming from behind and slightly to the side into the eye. If the light source behind can be eliminated, e.g. curtains drawn across a window, then the glare disappears.
There may be many sources of light that reflect from the glasses into the eye, for example due to multiple head orientations and light sources all around. In that case, blocking the light at the source is infeasible, but the rays causing glare can still be blocked closer to the eye. One way is to put side panels on the earpieces of the glasses. The side panel must touch the head with the edge closer to one’s back, so rays from behind cannot get between the earpiece and the head, so cannot reflect off the lens into the eye. The side panels can be cut from cardboard and slipped on the earpieces, as shown in the photo below.

The side panels will also block unwanted light coming from one side into one eye directly (without reflecting off the lens). An example is the Sun shining through a window to the side, causing eye strain.