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Inefficient Hot Water Piping Layouts Waste Hot Water

It's time to change building code provisions that allow designers and plumbers to build homes that waste hot water

Posted on Sep 25 2012 by Gary Klein

What is the key to an efficient piping layout for domestic hot water? The answer is to keep the volume of hot water between the water heater and the tap as small as possible. The difficulty is that most buildings have only one source of hot water and the many uses are spread throughout the floor plan.

The least expensive answer for new buildings would be to group all of the bathrooms near the kitchen, so that the home has one or more plumbing cores. That way, that hot and cold water uses would all be located close together, near the water heater or boiler that served them. In houses, this would typically mean one or two such cores.

In the absence of such cores, we need to plan the plumbing to supply hot water as efficiently as possible. Those of you who know my work have heard about Structured Plumbing. (For more information on Structured Plumbing, see Saving Water and Energy in Residential Hot Water Distribution Systems and Guidelines for Specifying Structured Plumbing Systems.)

Structured Plumbing is a method of running the trunk line of the hot water distribution system from the water heater past the hot water uses so that the volume from the trunk to each use is as small as practical, ideally less than 1 cup. In addition to routing the hot water supply close to each use, the Structured Plumbing approach includes a demand-initiated pump that allows the occupants to prime the trunk line shortly before they want hot water.

Green Building Advisor has had several articles on topic of efficient hot water supply over the years; see, for example, Hot-Water Circulation and Waiting for Hot Water.

A proposed amendment to the plumbing code

Current building codes permit builders to install piping systems that waste too much hot water. I’m now drumming up support for a proposed amendment to the International Plumbing Code.

The proposal would set requirements resulting in small volumes of hot water in the pipes between the hot water source and the use. It is intended to apply to all occupancies, although in the article I am focusing on residential applications.

The ICC is holding Final Action Hearings on October 22-28, 2012 in Portland, Oregon. The proposed amendments to the International Plumbing Code (IPC) will be heard on Wednesday, October 24th, starting at 1:00 pm.

Among the key provisions in the proposed change are:

  • a requirement that 3/8-inch pipe should only be used for fixture fittings that have a flow rate that does not exceed 1.5 gallons per minute;
  • a requirement (for some residential applications) that the maximum volume of water in the pipe between the water heater and a tap shall be 64 ounces;
  • a requirement (for some residential applications) that the maximum length of piping between a water heater and a tap be restricted to 50 feet for 3/8-tubing, 43 feet for 1/2-inch tubing, and 21 feet for 3/4-inch tubing.

To understand how these provisions would be implemented, it is essential to read the code proposal in its entirely. (See the link provided below.)

Assembling the required votes

To get this proposal adopted, we need to have enough code officials who support the measure to attend the hearing and vote for it. We need a two-thirds majority to prevail. So please talk with your local code officials and ask them to support it. If they are not able to travel to Portland, ask them to get you in touch with those from your state who are going to attend. If that is not possible, please ask them to send a short letter of support that can be read into the record.

If you are able to attend the meeting in Portland, short statements providing reasons why this proposal is worthy of a “yes” vote are in order. We need perspectives from the point of view of architects, plumbing engineers, builders and plumbers. I am willing to help you craft your testimony so that is most effective for this audience.

Proposed code changes

Now to the proposal itself: P130-12 (AMPC)-Klein is the most important of the proposals I have submitted. The proposal can be viewed on the ICC website. (To navigate through the document, click on the "P130" link in the sidebar that appears on the left side of the screen.)

Three other proposals — P89, P92 and P129 — concern recirculation pumps and pump controls for domestic hot water systems and are also worthy of your consideration. They can be found in the International Plumbing Code section on the ICC website linked to above.

The "reasons statement" accompanying the proposed code change

As an I-code, the IPC specifies minimally acceptable requirements for plumbing. Delivery of hot water to a user in a timely manner is one measure of plumbing performance. The American Society of Plumbing Engineers (ASPE) specifies the delivery of hot water to the user in 10 seconds or less as "acceptable performance," delivery of hot water to the user in 30 seconds or less as "marginal performance," and delivery of hot water in more than 30 seconds as "unacceptable performance". Implementing this proposal will improve health and safety by correlating the IPC with local health codes and with good plumbing engineering and plumbing practice. It will also result in satisfied users, including those in areas with low water pressure.

The core of this proposal is to make sure the volume of water in the pipes, which must be cleared out before hot water can be delivered, does not prevent the delivery of hot water in a timely manner. If you agree that delivery of hot water should be at least "marginally acceptable" in terms of time-to-tap, then you need to support this proposal.

Supporting Information
The following documents the values in this proposal and demonstrates the response to the committee’s comments. The committee [previously] disapproved P130 because the “volume limitations were too restrictive and unrealistic to apply to all buildings.” In response, this comment increases the lengths for smaller diameter branches from circulation loops or heat-traced lines. It also improves the readability of the code text.

Why implementing the 2012 IPC often results in “Unacceptable Performance”
The 2012 IPC allows for 50 feet of developed length [of piping] – of any diameter – from the source of hot or tempered water to the fixtures. However, the delivery of hot water is a question of volume (length and diameter) between the source and the uses and flow rate of the use. At current legal flow rates for faucets, showers and many appliances, 50 feet of piping contains more water than can be cleared out in the Marginally Acceptable time of 30 seconds or less, let alone the Acceptable Performance time of 10 seconds or less.

We are all familiar with the problem of waiting for hot water to arrive. When it takes too long at hand-washing sinks, many of us just give up and use whatever temperature comes out. When it takes too long at a shower, we watch the water run down the drain until the water is hot enough to use. When it takes too long in public restrooms or at hand washing sinks in food service establishments, it becomes a concern for our public health code colleagues.

Providing hot or tempered water to public lavatory faucets is a special case, and the reason we have called it out in this proposal. The time-to-tap is particularly important for hand washing events, which tend to be of very short duration, generally 5-10 seconds long. Large volume in the fixture supply piping, low flow rates and short events result in it taking a very long time for the water to get warm. Correcting this requires keeping the volume small enough so that hot water arrives in a timely fashion when only one faucet with a maximum fixture fitting flow rate of 0.5 gpmGallons per minute. Measure of liquid (usually water) flow. or a maximum volume per cycle of 0.25 gallons is being used. Having even Marginally Acceptable performance requires piping lengths much less than 50 feet long.

Can a volume limit be applied to all buildings?
Yes. The specifics have to do with the configuration of the hot water system within the building. There are three typical configurations for a hot water system: a central water heater (or boiler) with trunks and branches serving each use or group of uses; a central water heater (or boiler) with a circulation loop or heat traced trunk line and branches to each use; distributed water heaters (or boilers) located close to the uses they serve. Buildings can have one or a combination of these systems as long as the 2012 IPC requirement of no more than 50 feet of developed length on any path from the source to the use is met.

The volume limitations in this proposal work in any building. Buildings with vertical risers will be able to comply by locating the fixture fittings and appliances close to a circulated riser; this should not be a problem as they are relatively close already. Buildings with a central corridor circulation loop will be able to comply by locating the hot water fixture fittings and appliances closer to the corridor or by moving the loop closer to the fixture fittings and appliances. Buildings with public lavatories can meet the volume and length limits in this proposal in several ways including bringing circulation loops closer to the faucets, priming the branch lines that run behind the wall when people enter the lavatory, heat tracing the branch lines or installing water heaters in the bathroom or under the sinks.

In some buildings, no changes to architectural design will be needed – it will only be necessary to design and install the plumbing to meet the new code. In other buildings changes in the architectural design will be needed so that the hot water system will meet the new code. It is likely that we will see more buildings with combinations of hot water delivery systems. Based on my experience with improving the performance of hot water systems throughout the US, costs for additional water heaters or for somewhat longer circulation loops and heat traced trunk lines will be more than offset by the savings in smaller diameter trunk lines and in shorter branches that are often of smaller diameter because their length is smaller too.

What should be the maximum allowable volume?
Implementing the IPC should result in at least marginally acceptable performance at legal flow rates, in all occupancies, even in areas with low water pressure. The American Society of Plumbing Engineers (ASPE) has established performance criteria for the timely delivery of hot or tempered water (Domestic Water Heating Design Manual – 2nd Edition, ASPE, 2003, page 234). Table 1 [reproduced below as Image #2], taken from text in ASPE’s manual, presents the time-to-tap performance criteria. According to this table, 30 seconds is the maximum amount of time to have Marginal Performance. Anything longer is unacceptable.

So how much water is contained the IPC allowable limit of 50 feet of developed pipe length? Will clearing out this volume of water result in at least marginally acceptable performance? Table 2 [reproduced below as Image #3] shows the volume contained in 50 feet of pipe for nominal diameters up to 4 inches. (I realize that 50 feet of developed length is almost always shorter than 50 feet of pipe, but for simplicity, I have used 50 feet in the table.)

Let’s look at a few examples: 50 feet of ¾ inch tubing contains 1.2 gallons, 50 feet of 1 inch contains just under 2 gallons, 50 feet of 2 inch contains 7 gallons and 50 feet of 4 inch contains more than 28 gallons. This is the minimum volume that must be cleared out of the pipe before hot water will get from the source to the use. (Based on research conducted by the California Energy Commission, the actual volume that will come out before hot water arrives is more than volume contained in the pipe. In ¾ inch nominal pipe, approximately 25 percent more water will come out at 2 gpm; 50 percent more will come out at 1 gpm and 100 percent more will come out at 0.5 gpm. The amount of additional water that comes out gets larger as the pipe diameter increases.)

Table 2 [Image #3 below] also shows the consequences of the volume in terms of the time-to-tap for flow rates of 2, 1 and 0.5 gpm. This range of flow rates is typical of showers, sinks and public lavatory faucets. Near the top of the table, the minimum time to clear out the cold water in the pipe is shown in seconds, further down it is shown in minutes. (NA is shown when we considered the flow rate to be excessive for the pipe diameter – either too much pressure drop or excessive velocity, or both – based on an analysis using the Hazen-Williams formula.)

None of the times shown in Table 2 are within the Acceptable Performance range. This means that if plumbers or plumbing engineers design a hot water system to meet the minimum 2012 IPC, without also paying attention to the volume in the piping it will most often result in Unacceptable Performance. The best they can get is Marginal Performance in a limited number of cases. 

Table 3 [reproduced below as Image #4] compares the time-to-tap performance different volumes that are being discussed at this Final Action Hearing. The flow rates in the table are typical of faucets and showerheads, and many appliances such as dishwashers and washing machines.

Using ASPE’s criteria, only 3 data points in Table 3 have Acceptable Performance; 9 have Marginal Performance; all the rest have Unacceptable Performance. None of the volumes have Acceptable Performance for the low flow rates (0.5 gpm and smaller) found in public lavatory faucets. In addition, the Performance times shown in the 0.25 and 0.5 gpm columns are longer than the actual event itself, which is often only 5-10 seconds long. To make any sense at all, hot water must reach the faucet before the event is over, which is why there is a separate volume requirement in this proposal for the fixture fittings with these flow rates that are found in public lavatories.

We need to assess the performance when flow rates are between 1 and 1.5 gpm, not the maximum values of 2.2 and 2.5 gpm allowed by code for faucets and showers respectively. Why? One reason is that the flow rates of faucets and showers are rated at pressures of 60 and 80 psi respectively. In practice, operating pressures are often less than the rated pressure and the actual flow rate is less than the rated flow rate. In addition, hot water is only a portion of the total flow rate. The reduction in flow rate is most noticeable in areas with low water pressure to begin with. Another reason is that studies done in Indiana, California and Minnesota have found that even when full flow rate faucets and showers had been installed, the hot water portion of the flow was most often between 1 and 1.5 gpm. In this range of flow rates, the 300-ounce volume has Unacceptable Performance. The 75-ounce volume has both Unacceptable and Marginal Performance. The 64-ounce volume has Marginal Performance. The 24-ounce volume has both Marginal and Acceptable Performance. I believe the IPC should provide at least marginally acceptable performance at typical flow rates for all areas in the jurisdiction, including those with low pressure.

This section only applies to Public Lavatory Faucets
The time-to-tap is particularly important for hand washing events in public lavatories, which tend to be of very short duration. It becomes essential to keep the volume from the source to the use very small when the fixture fitting flow rate is only 0.5 gpm. Looking at the row for ½ inch nominal tubing in Table 2, the minimum time to clear out the cold water would be 1.2 minutes. Assuming that each hot water draw lasts 5 seconds, and that all draws happen right after each other, the 15th user would get hot water. If the branch line were larger, say ¾ inch, the minimum time increases to 2.3 minutes and the 28th user would get hot water. If the branch line was 1 inch, the minimum time increases to 3.9 minutes and the 47th user would get hot water.

The delivery of hot water to public lavatory faucets needs to be considered separately because of potential health issues. The events are short and the flow rates are low. Table 4 [reproduced below as Image #5] shows the time-to-tap performance based on the requirements in the proposal. The 0.25 and 0.5 gpm columns show that even at very low flow rates this volume will result in Acceptable Performance according to ASPE criteria. Given the short amount of time people spend washing their hands in public restrooms, it does not make sense to Marginal Performance category for determining the volume from the source to the use for public lavatory faucets. The volume was chosen so that hot water would arrive in the first part of the hot water event so that every person who uses the public lavatory will have the benefits of hot water.

Now to the decision
The provisions in the 2012 IPC (and previous versions), which only limit the feet, do not give guidance on the volume and as we have shown, often as not result in Unacceptable Performance. Unfortunately, many of us have experienced this! In contrast, this proposal contains the provisions necessary to support the correlation of the plumbing and health codes with good plumbing engineering design and plumbing installation practice.

There are 3 key questions that we are asking you to answer:
1. Do you want the IPC to support the provisions in local health codes to supply hot or tempered water for hand washing for every user of public lavatory faucets?
2. Do you want the IPC to support the ability of plumbers and plumbing engineers to provide hot water within 30 seconds after opening the tap; this is the Acceptable and Marginal Performance ranges as defined the American Society of Plumbing Engineers. (See the arrows next to Tables 3 and 4.)
3. Do you want the IPC to provide these levels of performance in all parts of your jurisdiction, including those with low water pressure?

If so, please support this comment.

Gary Klein is the managing partner of Affiliated International Management. His firm provides consulting on sustainability, primarily on the water-energy-carbon connection.


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Image Credits:

  1. Taco
  2. Gary Klein

1.
Tue, 09/25/2012 - 19:59

Edited Tue, 09/25/2012 - 20:04.

This code idea is NOT FOR
by aj builder, Upstate NY Zone 6a

Helpful? -2

This code idea is NOT FOR ME!

Next someone is going to be stationed in my home making sure I brush correctly for the correct amount of time to be certified by an independent licensed inspector that will have to take 4 credit hours of retraining every two years along with mandatory insurances for Liability, workers compensation, disability, health insurance, life insurance, auto insurance, hazmat training, CPR, Advanced first aid and more.

How about my idea, I won't be allowed to dream up my better simpler idea. Why? Illegal!!!

WE WILL IN ONE FELL SWOOP STOP INNOVATING AND LIVE IN THE DARK AGES!

WE NEED FREE MARKETS!

IF YOU WANT SMART FREE MARKETS THEN YOU DO LIKE WE JUST DID WITH CIGARETTES. TAX THE HELL OUT OF WATER AND PEOPLE WILL BEG ME FOR SOLUTIONS!

THIS LAW IS THE EASY WAY. NOT THE RIGHT WAY.

Caps lock must have stuck... Excuse me.

So, here's a smart easy way to not need the rule stated above or the silly device that costs money, breaks down, needs servicing and replacement. And who the heck wants to push a button to run this thing every time they use water???? Not most people. Adding complexity. Silly idea. Really silly.

Do this. pipe hot water to the toilet. Yup, thinking ass backwards is the simple solution. No switch, no labor, no motor, no electricity, no outlet, no nothing. Saves hundreds in installation. And no servicing.

Here's the deal. figure the water needs of the toilet and make sure the run to the toilet holds that amount of water. Bingo. Enter the room, use toilet, water is now rushing to bathroom, next hit the shower or the sink and no water is wasted because hot water has just arrived perfectly and with no majic expensive device and all that is not wanted dragged along with the not needed device.

I am totally against this blog, and this crazy over regulation by non thinking non innovating rule making types.

I think people who make rules for a living,. make more because, that's their job, to make rules.

We need all rule makers to always allow for innovation and experimentation. And we need all rule makers to mandatorally remove two rules for every rule they make.

Right now if you enter a law library, the number of books on the shelves would make every one of you feel the same as me.

Yes, I can edit this to go away or be a little softer. let me know if I am way off track.


2.
Tue, 09/25/2012 - 20:07

The picture of the water
by aj builder, Upstate NY Zone 6a

Helpful? -1

The picture of the water pump. Show that to 100 customers and let me know if one of them wants to lose their storage space with a contraption on display.

I may use that picture from now on to show customers what they won't want from others.


3.
Tue, 09/25/2012 - 22:44

I gave up long ago.
by Gordon Taylor

Helpful? 0

I wash my hands in cold water. It saves time, keeps my skin raw and manly, and has not yet resulted in cholera or typhoid. For my new house, however, I will (without pumps and gadgets, because, like AJ, I like putting things under the sink) follow the guidelines as well as I can.


4.
Thu, 09/27/2012 - 00:17

To AJ
by Gary Klein

Helpful? 0

Thank you for both comments. Although the picture at the lead of the blog shows a demand initiated pump located under the sink, this code change proposal is not about the pump. Rather it is about the volume of hot water between the source of hot water and the uses. As best I can tell, you have not yet read the proposal, which in all fairness, I would ask you to do.

I most certainly do not want to regulate your activities in the bathroom, nor does the proposal intend to do so.

I like your idea of attaching the toilet to the hot water supply and using the volume in this piping to bring the water from the water heater to the bathroom by flushing the toilet. Clever idea, but I am not sure how practical it will be in practice. If the code change is approved, it will help you calculate the volume more easily by ensuring that the volume from the water heater to the bathroom will be no more than 0.5 gallons.


5.
Thu, 09/27/2012 - 00:31

To Gordon
by Gary Klein

Helpful? 0

Thank you for your comments. I gave up on getting hot water many years ago too. For washing hands, all I want is water warm enough to keep my hands in for the time it takes to scrub them. I don't like winter water temperatures in say Minneapolis, but a temperature around 75-80 F seems just fine.

However, I really want hotter water for my showers. Due to the way we build our houses, we have all learned to put up with the time it takes for hot water to arrive in the bathroom or kitchen, depending on which is furthest from the water heater. The purpose of this proposal is to limit the volume in the pipe between the source and the use so that time-to-tap will be more reasonable and more consistently predictable throughout the house.

The best result will be that architects and builders, while still focusing on a providing a good layout and floor plan, will cluster hot water locations closer to each other and to the water heater that serves them, thus limiting the volume in the piping by a more efficient design.

By the way, it will be less expensive to build such a house because there will be fewer feet of hot, cold and drain water piping. I assume that will be acceptable...


6.
Thu, 09/27/2012 - 22:51

Reply to Gary Klein
by Gordon Taylor

Helpful? 0

I think I understand what you're talking about, and I will certainly make every effort to shorten hot water runs in my new house. I wish you luck with your efforts. I really appreciate the graphs showing the capacity of various sizes of pipe.


7.
Thu, 09/27/2012 - 23:31

Edited Thu, 09/27/2012 - 23:33.

To Gordon
by Gary Klein

Helpful? 0

You are most welcome. Would you like a guideline for what we call Structured Plumbing?

There is an article in the Official magazine from IAPMO that compares the performance of two different 1 quart hot water distribution systems. It shows that traditional trunk and branch outperforms central home run, even though any path to a fixture is no more than 1 quart. Would that be useful too?


8.
Sun, 09/30/2012 - 12:35

Edited Sun, 09/30/2012 - 12:54.

That main picture is so bad.
by aj builder, Upstate NY Zone 6a

Helpful? 0

That main picture is so bad. Yaa all should take that picture down and destroy the hard drives that it resides on. Do a proper install that a customer would love and retake that picture!

Anyone doing an install like that losing the entire cabinet space to a useless invention should lose their plumbing license for eternity.

Are we really trying to show our customers how little thought we give to what we do for them? "Write me a check for $450, you're going to love saving so much money and water now.... But you lost the cabinet space you liked?... ahh... well.. you are saving the planet, the aquifers are drying up... Really? Seems like it rains so much this last decade that I forgot what the sun looks like... Trust me darlin... this is good for you and the future of this planet... trust me.. I read about it at Green Building Advisor so it must be right."

More "what's wrong with this picture"... We are selling an expensive option... to save money.. to a customer that would buy a $16 dollar faucet, $48 cabinet, and have an electrician surface mount a recepticle for who knows how much, $160 using a flush mount cover? How much do we see wrong with this picture? I know one thing. I never have installed what I see in this picture and never will. Could be just me though. Isn't GBA a follow on from Taunton to.... FINE Homebulding???

Taunton, Fine Homebuilding is tops. This picture is... something other than... I hope you can appreciate my critique as I think the most of Taunton, Fine Homebuidlng, and GBA mostly because of Martin Holiday.

That all said,,,, let's all have a great day... may your football team win.


9.
Mon, 10/01/2012 - 01:40

Edited Mon, 10/01/2012 - 01:50.

AJ, this article isn't about pumps under sinks
by Kevin Dickson, MSME

Helpful? 0

I did a quicker review of this issue in a recent blog post:
http://greenbuildingindenver.blogspot.com/2012/07/plumbing-efficiency-in...

As I see it, here's what it boils down to for a new, medium size, low energy house:

No 3/4" hot pipe, use PEX, use mostly "home runs", use 3/8" pipe whenever possible. More pipe and less fittings will save a lot of energy, water, and hot water waiting time. Plumbing codes have always specified minimum pipe sizes, and now should also specify maximum pipe sizes for energy and health reasons.

Gary's "Structured Plumbing" is actually a way of reducing the need for those heinous DHW recirculation pumps.


10.
Mon, 10/01/2012 - 05:23

Response to AJ
by Martin Holladay, GBA Advisor

Helpful? 0

AJ,
It could always be worse -- see the photo below.

D-Mand pump installation.jpg


11.
Mon, 10/01/2012 - 05:26

A neater installation
by Martin Holladay, GBA Advisor

Helpful? 0

AJ,
This one is a little better:

D-Mand pump installation - better.jpg


12.
Thu, 10/04/2012 - 02:42

AECB Water Standards
by Mark Siddall

Helpful? 0

Below are the AECB water standards. They are voluntary rather than regulatory. I thought that these links may be an interesting addition to the debate. http://www.aecb.net/PDFs/waterstandards/1503_AECB_Water_Vol_1_V3.pdf
http://www.aecb.net/PDFs/waterstandards/The_AECB_Water_Vol_2_V3.pdf

Below is a paper examining the DHW demand Passivhaus and other building types. It serves to demonstrate that once you acheive the Passivhaus standard for fabric efficiency attention would be better focussed upon the design of DHW systems (using standards akin to those of the AECB).
http://www.aecb.net/PDFs/Clarke_Grant_Hot_Water_System_Design_2010_Paper...


13.
Thu, 10/04/2012 - 07:09

Edited Thu, 10/04/2012 - 07:10.

Response to Mark Siddall
by Martin Holladay, GBA Advisor

Helpful? 0

Mark,
Thanks for the link to the second paper. It's good to remind designers of superinsulated homes that our traditional obsession with space heating energy needs to be tempered with a better understanding of domestic hot water energy use, since DHW energy makes up a larger percentage of energy use as we get better at designing building envelopes.

Passivhaus builders in the U.S. have discovered that American families use more hot water than the default assumptions in PHPP. It's interesting to discover that this has been noted in other countries as well: "Our analysis of actual water use shows that in the UK hot water use is typically at least 30% higher per person than is assumed in PHPP."


14.
Thu, 10/04/2012 - 07:33

Response to Mark Siddall
by Gary Klein

Helpful? 0

Thank you for the links. I would observe that the volumes in the dead legs are smaller than those proposed for the IPC. 1.5 liters is about 48 ounces; 0.85 liters is about 28 ounces; 0.5 liters is about 16 ounces; 0.25 liters is about 8 ounces. Seems to me like the proposal before the IPC is conservative.

I also thank you for the comments on the magnitude of hot water in energy efficient houses. This percentage has been growing for some time, it was just under our radar.


15.
Thu, 10/04/2012 - 07:48

Edited Thu, 10/04/2012 - 07:49.

More on the origin of the PHPP default values
by Martin Holladay, GBA Advisor

Helpful? 0

For those interested in the PHPP default values for domestic hot water consumption, here are some interesting links:

A German in America:
"Q. A sensitive issue that people are often reluctant to discuss concerns the cultural differences in personal hygiene. What are your own experiences?

NETTERFIELD: My husband, like almost any American, showers at least once a day, every morning. Most days he also showers after exercising. That makes two showers every day. In Germany people bathe once a week on Saturday evening.

Q: So the old US joke about bathing once a week whether we need it or not is actually the German practice?

NETTERFIELD: I still to this day do not shower regularly every day. I wash in strategically important places every day, but usually will only bathe once a week. When my mom visits us here in the US, she even notices that most people here will not smell like old sweat, but like they are freshly washed. When you are in an elevator in Germany or any other closed confined room, you will smell stale sweat from unwashed bodies. It's just what people are used to."

* * * *

A scholarly paper on the issue: Personal hygiene and cleanliness in an international comparison: "The following general findings were established: (1) In the Federal Republic of Germany the attitude towards hygiene and cleanliness has improved over the last 20 years. (2) The level of hygiene and cleanliness in France and Spain is significantly higher than in the FRG."


16.
Thu, 10/04/2012 - 19:18

Water use
by Mark Siddall

Helpful? 0

In Passivhaus buildings water efficient taps and appliances are necissary. UK studies have so far focussed upon regular homes that do not have such levels of efficiency. I have a hunch that once water efficient appliances are installed the water usage will diminish somewhat. Whether it matches German experience is another matter but it is worth noting this data gap.


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