A Call for Permeable Paving

with permeable paving, stormwater doesn't all become surface runoff

With permeable paving, all stormwater doesn’t become surface runoff
Image Source: Flickr

I’ve said it before and I’ll say it again: urban dwellers have an obsession with paving every possible open space.

Housing society compound?
Pave it — we need to park our cars!

Open area where social interactions take place?
Pave it — our clothes get muddy!

Barely-used internal road?
Pave it — we get stuck in the monsoon and it’s hell on the tyres!

If we Must Pave, Let it be Permeable

Some of this paving may well be justified but, because it is done indiscriminately, it leads to a boatload of problems related to the water table, the health of the city’s trees and even the heat we’re subjected to. I’ve written all this in greater detail elsewhere on this site but this particular post is about a type of product that could help in such situations.

In late 2015, there was a buzz in the construction world as Lafarge UK showcased a super-porous asphalt that could guzzle an incredible 4000 litres of water in about a minute. Media started calling it “thirsty concrete” and truly, if you watch the video below, it does look like the water is vanishing into desert sands.

Permeable Concrete Video

I have never been a great fan of the wasteful use of concrete but, when it is required, the least we can do as architects is to try and use it correctly.  Unfortunately, at least as far as I can tell, this product and others like it are not readily available in India. In fact the only case I know of permeable concrete being used, is for a parking lot at Jaipur railway station.

Unless architects and engineers specify such products and create a market for them, there is no way that companies will manufacture them here. I do hope some of my brethren in the industry take up the call.

Reduce Hard Paving

In our urban environment we see numerous examples of open spaces with hard paving all over them. One of the reasons for this is our insatiable hunger for parking. The earth in our cities is starved of air and water — sacrificed at the altar of our rubber-shod tin cans.

“Ah”, but I hear you say, “we really do need that parking space!”.

Of course, if our city fathers were more enlightened and aimed for better public transportation instead of caving in to the cult of the car, we wouldn’t have reached this impasse in the first place. However, this page is not a rant about ineffective urban planning but about the effects of indiscriminate paving and what we can do about it.

When we pave over open spaces, a number of things happen.

The Water Table Drops Dramatically

This one is pretty obvious and hardly needs an explanation. If the ground is paved, there is no way that any more than a tiny fraction of rainwater will ever reach the soil. In Bombay, there was a time when one could dig a well and hit water not far below the surface. These days, the only reliable wells are the ones that adjoin large green spaces — like the maidans for example.

Other cities are not so lucky and those who live where borewells are common will tell you that the wells need to be dug deeper every year. The water they reach is also an increasingly fickle seam. The demand on the groundwater is constantly on the rise but all that paving never allows it to get recharged.

Egress of Saline Water in Coastal Areas

too much paving leads to a drop in the water table which allows egress of saltwater

Freshwater is lighter than saline water

Saltwater is denser than freshwater and forces its way inland below the latter. If the (fresh) water table drops, the boundary between them is pushed deeper inland. Salinity in the soil is not merely bad for plant life but also for construction.

Trees Find it Difficult to Survive

For plants — and especially trees — paving is doubly detrimental. Not only is there very little water in the soil to help them grow but their roots are also unable to breathe. As a result, the trees develop a weak rooting system; it is no wonder so many of them topple over during the monsoons. That many of the avenue trees in our cities are fast-growing exotics, doesn’t help very much either.

Drainage Systems are Overwhelmed

Kalyan Station under water July 2005

Kalyan Station under water
Image source: Wikipedia

When it rains in an urban area that is excessively paved, the runoff has to go somewhere! That somewhere, is the storm-water system which is frequently unable to cope. This leads to the all-too-familiar floods we see every year.

At best, flooding is an inconvenience but, as the last few years have shown us, it can also be deadly. Corrupt builders, politicians, and bureaucrats are responsible for the rampant encroachment on natural drainage channels in many of our cities. This results in the kind of devastation and loss of life we saw in Bombay (2005), and Madras (2015).

No doubt, in both cases there had been uncommonly heavy rainfall. We must remember, however, that climate change is causing an increased frequency of such extreme events, so it would be foolish to brush them aside as a freak events.

Worsening of the Urban Heat Island Effect

urban heat island

Temperatures are significantly higher in cities
Image source: Wikipedia

Paving is one of the major factors leading to the heat island effect — that phenomenon where an urban area is significantly hotter than its surroundings.

Unlike soil which cools off rapidly when the sun goes down, paving retains heat for longer and then emits it slowly through the night. One of the only ways to reduce this effect is to increase the area under plantation (including on roof terraces). However, as we have seen earlier, that is rather hard to do, when everything has been paved over. It’s a bit of a vicious cycle.

What We Need to do

Of course the very best thing to do is to avoid paving as far as possible. However, there are many situations when we really have no choice. At such times, the least we can do is to use materials and systems to mitigate the problems we cause.

Pervious Concrete Paving

permeable concrete

Permeable Concrete
Image Soure: Wikipedia

This is a type of concrete where the fine aggregate (sand) is missing so that the concrete becomes porous enough for water to percolate through. This means, of course, that it is not as solid as other concretes and cannot sustain the same heavy-duty usage. On the other hand, it is perfectly usable in areas where traffic density is low or, for example, in parking lots.

Some cities like Portland, Oregon in the USA have experimented quite extensively with permeable paving. Unfortunately, there is little sign of anything even remotely close being done here.

Perforated Paving Block or Grass Paver

grass paver blocks

Grass Pavers
Image Soure: Wikipedia

These are easily available here but not as commonly used as I wish they were. They are easy to lay and, to my eye, they make a space look much nicer than if were completely covered with a hard surface.

Permeability is excellent but, like porous concrete, it can only be used for low-traffic areas or parking lots.

Tree Guards

tree guard

Tree Guards
Image Soure: Flickr

If all else fails — and even if not, it is wise to have tree guards which allow the soil around the roots to breathe. This is something that is conspicuously lacking in our cities.Instead, we see a low brick wall made as close to the trunk as possible. Apart from being undersized and ugly, these are also tripping hazards for pedestrians.

It would be so simple, instead, to embed a cast iron tree guard that is level with the pavement. If the city authorities feel that the iron will be pilfered, they can do something similar in ferro-crete. It won’t look half as nice but at least it will be effective.

Green Roofs

green roof

Green Roof
Image Source: Wikipedia

While a green roof can’t do very much for the surface runoff and the storm-water systems, it can certainly be help reduce the urban heat island effect.

Planted roofs haven’t caught on too well here as yet. That will not change until waterproofing systems become much more reliable. People who have running battles with monsoon leakage are unlikely to tempt fate.

Conclusion

The situation is far from ideal but it isn’t a lost cause just yet. Given enough awareness and pressure from the general public, things can improve. Organisations like depave, for example, have done this very effectively. They have not only raised awareness in Portland but have even forced the local government to reverse past mistakes.

Maybe it’s time to start something like that in all our cities here as well.

Pro Bono Pledge

pro bonoIt’s almost a quarter century since I became a practising architect and, although I have been doing pro bono design work over the years, it has always been for people or organizations that know me directly. This way I do no more than a couple of days worth of pro bono work in the entire year.

Starting this April, I have decided to put aside one hundred hours every year for pro bono work. It could be any non-profit although priority will be given to assignments that are connected in some way to the environment or to education.

In the USA, there is an organization called 1+ which asks design houses to donate 1% of their time to non-profit work. That works out to about 20 hours per person each year. They then put people in need designing done in touch with those who do it.

Unfortunately this organization has no chapters in India so it looks like I’m on my own here and will have to rely on my friends, and the readers of this website to get the message out.

Ground Rules

There are a few things to remember and it is best to put them down so there is no confusion later.

  • The project and the organization undertaking it must genuinely be not-for-profit.
  • It must be for a good cause.
  • No single assignment will be allotted more than 40 hours.
  • If any travel is involved, it has to be paid for.
  • If any fancy presentations have to be made I will only provide the raw design. You do the rest.
  • If you want detailed estimates of cost, please get in touch with a builder / contractor. At best, I will be able to give you rule-of-thumb costings.
  • I will try and do the required work as quickly as possible but please understand that my paying clients have priority on my time.
  • Ultimately, the decision on whether to take up an assignment or not, rests with me.

Please share this page with people you think might be interested. If you do, someone, somewhere will be able to use the information. If it just sits here, nobody benefits.

ShKo Bungalow

Many people dream of leaving the city to lead a slower, more meaningful life outside it. Few, however, are able to live that dream. Just a stone’s throw from the [RaBV] bungalow here is a sustainable weekday home of a couple who come into the city on weekends.

Site Conditions

Satellite images of the site showing how the flood zone determined the final house location.

Satellite images of the site showing how the flood zone determined the final house location.

Much of this one-acre site is between 1.5 and 3m above the average water level of River Pej, so during the monsoon, the lower section of the plot is often flooded once or twice for a few hours at a time. The initial plan was to build almost touching the river but that would mean building on stilts. Instead—taking into consideration the high water mark of 2005 which saw the worst flood in living memory—we decided to build on a small rise at the other end of the plot. Thanks to climate change, such freak events as the cloudburst of 26th July 2005 are likely to happen with increasing frequency and we must understand and prepare for them instead of brushing these facts under the carpet.

Because of the sloping land we have a large basement

Because of the sloping land we have a large basement

The little rise is next to the access road so the approach to the car parking area is a little steep but, other than that, there are no disadvantages. There used to be a shed on this mound so there were no trees that needed to be designed around.

As the building is on a slope, the extra height at the bottom has been used to create two basements. One stores gardening and filtration equipment along with the rainwater harvesting tanks while the other has batteries, inverters and other electrical equipment for the photovoltaic solar panels.

The foundations and plinth of the bungalow being made of local black stone.

The foundations and plinth of the bungalow being made of local black stone.

Design Considerations for Sustainability

Climate data for the location which helped make a more responsive, passive solar design.

Climate data for the location which helped make a more responsive, passive solar design.

As with the [RaBV] bungalow, the climatic conditions to be considered were hot days and pleasant nights with a strong monsoon. We needed sufficient shade on the South and West sides and this was taken care of with deep verandahs. Air circulation and cross-ventilation were important to eliminate the build-up of hot air. For the most part, roofs are sloping with only a small fraction of flat terrace where the solar hot-water systems are placed.

ShKo Layout Plan

ShKo Layout Plan

Instead of a typical compact layout, this house was designed as a series of spaces with clear zoning of public and private. When seen from a distance–and a height–it looks like three houses in a cluster rather than just one. Central to all three spaces is the court and the open tank. This is not some amoeboid pool for people to float around with a cold beer but a straight 15m strip for exercise. Oh, and it’s a tank because, well, it’s a tank. Water from here goes to the vegetable garden and to many of the trees on this plot.

The clients, currently in their early 50s, want to spend the bulk of their time here exploring their creative side. Accordingly, one of the major spaces in the house is a workshop to be used for painting, stained-glass making and sliver-smiting. There is also a small study, two bedrooms, a utility room, a living/dining room and a very large kitchen.

Materials & Systems

Exposed brickwork, Mangalore roof tiles and windows made from reclaimed wood.

Exposed brickwork, Mangalore roof tiles and windows made from reclaimed wood.

The foundations were constructed from local basalt and the superstructure from local bricks.We discussed the possibility of using fly-ash bricks but the clients had reservations because of the debate over fly-ash being carcinogenic.

Many internal walls were left un-plastered and the roofs had a steel structure with Mangalore tiles on battens without any under-layer.

One of the old wooden pillars

One of the old wooden pillars on its granite-clad base.

Doors and windows were either beautiful old ones that were salvaged from demolished homes or were made anew from reclaimed old Burma teak. The credit for sourcing them all goes completely to the clients. They also purchased five lovely old wooden pillars during their travels, which were incorporated into the design. Since these were only 2.5m tall, we made a tapered concrete base which was then clad with the same grey granite as was used for the adjoining parapet walls.

Energy

All the lights are low-energy, mostly LEDs, while the fans and refrigerator are inverter-type so their energy consumption is also lower than average. As these fans are a relatively new product, it remains to be seen if they stand the test of time.

Bath and kitchen water is heated using one solar panel on each of the terraces. There are also twelve photovoltaic solar panels on the roof of the workshop which provide enough electricity to run all the lights and fans as well as some of the appliances.

Water

The rainwater harvesting filter

The rainwater harvesting filter

A good amount of the rainwater is harvested. Some of it is collected in tanks for drinking water throughout the year. This is necessary as the river, though perennial, sometimes contains urea washed in from fields upstream; even though the water is clean enough for bathing and washing, it is not advisable to use it for drinking or cooking. The remaining harvested rainwater is used for recharging a bore-well that is an emergency backup water-source. Whatever rainwater is not harvested either seeps into the ground or flows directly into the river.

Embedded dual cisterns flush the low-flow WCs and kitchen waste water is sent directly into a soak-pit from where it percolates into the ground.

And finally, some more images
 View through the brick jali  View of the curved verandah
 View of the Tank  View of the court at night

 

Project Participants

Consultants
Structural & Waterproofing Mr. Ratnakar Chaudhari
Contractors
Overall | Civil, Plumbing, Roofing, Painting Mr. Rajesh Phatak
Electrical Mr. Rafeek Shaikh
Carpentry & Joinery Mr. Ramashankar Mistri
Specialised Agencies
Solar Hot Water Solar World
Solar Photovoltaic | Panels, Batteries, Inverters Sunlit Future
Swimming Tank Filtration Oceanic Enviro Pvt. Ltd.

TERI and USGBC to join forces

TERI & USGBC to join forcesNow that was unexpected!

New Delhi, June 7: The Energy and Resources Institute (TERI) and the U.S. Green Building Council (USGBC) today announced a strategic collaboration to accelerate the development of high performance buildings in India and Southeast Asia.

Essentially, apart from lavishing praise on each other in their press-releases, they’re talking about making it easier for projects to have dual certification by “offering seamless pathways” to do so. However, what we still don’t know–and what they haven’t spelt out–is how they plan to reconcile their fundamentally different approaches to sustainable construction.

One wonders what compulsions made these two reach out to each other. Let’s not fool ourselves that it was an altruistic move for the betterment of all mankind. This was a hard business decision and there must be some powerful financial reasons behind it.

What will it mean for the future of GRIHA? Are they running scared because LEED certification has greater aspirational status and because India is already the third largest market for them outside of the USA? On the other hand, GRIHA is officially backed by the Indian government so, is LEED trying to stick a foot in that door now?

Time will tell of course but I can’t help feeling that TERI has made a blunder.

Press releases from TERI & USGBC

Edit: On request from TERI, the image in this post (which originally contained their logo) has been changed. Was I cutting too close to the bone?

The Changing Face of Lighting

LEDs are changing the face of lighting

LEDs are changing the face of lighting

My first encounter with LEDs was for a school project where I wanted to use one as a little red indicator. In those days, they were simply Light-Emitting Diodes, nothing more. The though that they would, one day, be used as a source of light didn’t even remotely cross my mind.

In the last few years, however, LED technology has taken giant strides and the early problems like inaccurate colour rendition and a limited light-cone have been, to a great extent, sorted out. Added to that, the costs–which used to be very high–have come down to relatively affordable levels. While they are not, still, competitive with fluorescent lights, the day is probably not far when LEDs will replace them.  Even at today’s prices, they are already more economical in the long term.

With their small size and favourable physical properties—they run cool, have a long life and are able to vary their colour—LEDs have made it possible for lighting designers to come up with some very original creations.

Image derived from | https://en.wikipedia.org/wiki/File:On-state_off-state_white_LEDs.jpg

Micro Houses

A photo feature on unconventional tiny houses got me thinking about why we never hear of architects designing them in India.  Is it because a very small house is much too readily associated with poverty that we, as a country, are trying to leave behind? Or do we insist on big weekend houses on the off-chance that extended family and friends will come visiting and need to be accommodated?

tiny footprint

Micro houses have a tiny footprint

Whatever the reason, the concept of micro-houses is rarely considered seriously here–although it should be–because because they costs a lot less to build or maintain and, more importantly, they reduce our carbon footprint in a very big way.

We have a long tradition of frugal construction and it’s about time we rediscovered it. Maybe one day, hopefully in the near future, someone will ask me to design one. Or a bunch of them.

The Gaming of LEED Ratings

We all know that the LEED system can be gamed but that it could be turned so completely on its head was news to me.

greenwashThe Bank of America building at One, Bryant Park, New York has a LEED Platinum rating and was the first skyscraper to ever be awarded this but now, it turns out, it uses more energy per square foot than other building of similar size in all of Manhattan. Wow.

It was hailed as a major achievement by none other than Al Gore who set up his offices there. The basic problem is that LEED is largely based on computerised energy models and “intent”. This makes it open to abuse because it’s easy to purportedly intend something at the design stage and then change the goalposts later on.

Coincidentally, just this morning, I was speaking to a couple of marketing guys who were trying to convince me to attend a “green summit” next month and one of their selling points was LEED. I declined, telling them exactly what I thought of LEED but I wish I’d seen this article just a few hours earlier:

Bank of America Tower and the LEED Ratings Racket via: ArchRecord

Glaring mistakes

conventional v/s curtain wall

In hot climates, the overall energy usage rises as you increase the glazed area. Curtain walls, therefore, are highly inappropriate.

I have ranted about glass façades for a long time and this editorial by Sunita Narain of DTE has inspired me to add a couple of paragraphs to the original one.  Among other things, she has written about a recent study by IIT-Delhi which found that, in our hot climate, the manufacturers’ claims of special coated glass or double/triple glazing being able to reduce heat gain are rather hollow.

One of the other specious arguments put forth in an attempt to portray glass curtain walls as green systems is to say that it reduces the electricity consumed for lighting. This is a half-truth. Leave aside the uncomfortable glare that people working inside such buildings have to put up with, let us make a simple comparison.

Consider a 10m² conventionally designed space. Assuming that we don’t take passive cooling techniques into account, the air-conditioning load will be in the region of 3,500W (1 ton).  Lighting the same space, on the other hand, will need just 50W with fluorescents or 40W if we’re using LED fittings.

Now, imagine a similar sized curtain-walled space. The maximum saving that can be achieved by reducing lighting is a puny 50W. However–and this is the big problem–air-conditioning requirements will probably have risen to a whopping 5,000W.  Even with all the specially coated and multi-layered of glass in the world, the total requirement is unlikely to be anything less than 4,500W.

So yes, we may not use as much electricity for lighting but, I’m afraid, the energy usage for cooling will go right through the roof and no amount of marketing spin can get around this simple fact.