Every Community a Powerhouse

Green Communities

CCBF and University of Hong Kong published a paper “Every Building a Powerhouse”  they missed the point and an opportunity.  I am afraid that the academic’s still don’t get it. What is needed is “community” scale,  a cluster of buildings, an estate, development or community these can yield cost effective low carbon solutions.  And it’s not a new concept, think about district heating – its has been tried and tested in Europe and USA for many decades. However, what I propose here is an expanded that concept, to go beyond district heating to use 21st century design ideas and technology, essentially a blueprint for a sustainable green community.

Ask an Engineer

Engineers spend a lot of their time struggling to match demand and supply profiles in a building. However, if we consider the wider picture in a community opportunities arise from diversity, the diversity amongst a number of buildings in a community. Think about an office block and a residential tower, during the day light hours the residents are in work and the building consumes little energy, whilst the office is occupied demanding air conditioning during the day.

Using Community Resources

Hong Kong is sadly lagging behind other first world nations in its handling of Municipal Solid Waste (MSW), every year another reminder is sounded the landfill sites are exhausted, yet the policies don’t change, MSW is collected and transported across the territory burning diesel fuel to the near bursting capacity landfill sites.

waste energy management kelcroft

The typical housing estate or development has opportunities municipal solid waste is only one, the sewerage, energy use, but these are invisible, hidden from people in our communities, and in my encouraging the NIMBY attitude.  We should know by now- throw it away! means get it away from me.  However, no single community or district should be forced to bear a huge portion of the environmental burden for the entire population of Hong Kong.

In areas like Hong Kong and Singapore, where land is scare, dump waste into landfills is simply not sustainable, government agencies are starting to recognise the problems, but the solution is not tackled.

A community based solution means the waste owners need to see the results of their own waste, in the energy sector we often say if it not measured is not managed, and the same is true for waste management. Its going the be difficult to encourage households to reduce or manage municipal waste whilst it remains hidden and silently moved to a distal landfill far from their own backyard. Instead, I propose these valuable waste streams should be used in the community for the community.  Where excess green electricity is generated it should earn a significant premium for the community generator from the utility companies. 

Waste used for local power generation, sewerage for local methane production, rainwater harvesting for local water use. The main advantage for local community based solutions, over the single building is that the supply and demand profiles are diverse, where one building requires more water, another building with lower usage can meet the demand.

On the topic of waste, we need to see the big picture, organic material from the countless garden and sitting out areas is collected by hand and stuffed into ubiquitous black plastic bags for disposal, presumably sent to the landfill. At the same time, tonnes of fresh organic material is imported for building new gardens, there is a very obvious disconnect, the necessary policy to manage environmental resources is missing. Waste food can be rapidly processed into compost also.

Chiller Load Profile – why install two air conditioning systems when one will do

Other past projects, including green buildings have shown that where people can be engaged the value of the investment increases,  making the community a more desirable location will also impact the real estate market significantly increasing property valuations.

We should have progressed further, yet the environment continues to provide “free” resources divorcing us from the true cost of materials, water, and energy.  There are kept  artificially low because nobody sends in a bill for polluted air, not a great incentive for recycling or effective management is it? It’s time for a change.

 

Water Conservation – sea water flushing

For more than 50 years seawater has been used for toilet and urinal flushing in Hong Kong, saving significantly quantity of fresh water. If you are near the coast, the process is straightforward, sea water is filtered, treated and then pumped to purpose built service reservoirs ready for use in residual and commercial buildings. Eighty percent of Hong Kong buildings are served by the sea water infrastructure.  In the year 2011, the potable water savings were 740 tonnes per day,  or more than 270,000 tonnes per year.

All new buildings by regulation mustbe provided with two separate water systems, potable and flushing water. The flushing water infrastructure must be designed to handle sea water.  in buildings uPVC is the material of choice for pipework serving all sanitary appliances.  WC cisterns are designed without any metal components exposed to the corrosive seawater.

WSD Distribution Diagram

Underground the pipework distribution utilises cement lined piping for sea water to the service reservoirs and buildings as shown in the above diagram (courtesy of Hong Kong Water Supplies Dept. https://www.whittonplumbing.com/24-hour-emergency-service/).

Having separate potable and sea water infrastructure has another advantage, in the event that one water service is shut-down for maintenance, that doesn’t stop all the water services. Furthermore, since the sea water provides part of the buildings water demand, the potable infrastructure is smaller and lower cost.

One of the major objections against using sea water is a concern that potable water and seawater piping could be cross-connected, in reality that’s an unlikely occurrence because the materials are different, its physically difficult to connect a cement lined pipe to PE piping.

China is starting to embrace sea water as a resource too.

Its obvious really, in coastal areas, why flush our precious potable fresh water down the toilet? The use of sea water is a low-tech solution to lower and conserve potable water usage, and very cost effective.

Update: John Herbert was appointed to the Hong Kong Green Building Council Faculty June 2012 and chairs the Water Aspects technical group.