10 Green Building Trends for 2011

What’s to come on the sustainability front in the new year

Green building is going mainstream, no doubt. But exactly how is building science evolving, and where are eco-minded builders and consumers likely to focus their attention in the year ahead, in light of current economic conditions? The nonprofit Earth Advantage Institute, which to date has certified more than 11,000 sustainable homes, makes some predictions for 2011 in its annual forecast of green building trends.

Affordable green. Many consumers typically associate green and energy-efficient homes and features with higher costs. However, the development of new business models, technologies, and the mainstreaming of high-performance materials is bringing high-performance, healthy homes within reach of all homeowners. Leading the charge are affordable housing groups, including Habitat for Humanity and local land trusts, now building and selling LEED for Homes- and ENERGY STAR-certified homes across the country at price points as low as $100,000 (in the case of land trusts, homeowners do not own the land their homes are built on). In the existing homes market, energy upgrades are now available through new programs that include low-cost audits and utility bill-based financing. Through such programs as Clean Energy Works Oregon, and Solar City’s solar lease-to-own business model, no up-front payment is required to take advantage of energy upgrades.

Sharing and comparing home energy use. As social and purchasing sites like Facebook and Groupon add millions more members, the sharing of home energy consumption data – for rewards – is not far behind. The website Earth Aid lets you track home energy usage and earn rewards for energy savings from local vendors. You can also elect to share the information with others on Earth Aid to see who can conserve the most energy. When coupled with other developments including home energy displays, a voluntary home energy scoring system announced by the Department of Energy, and programs such as Oregon and Washington’s Energy Performance Score, a lot more people will be sharing -- and comparing -- their home energy consumption.

Outcome-based energy codes. Existing buildings are responsible for most energy use and associated carbon emissions, but the prescriptive energy codes used in commercial remodels don’t encourage effective retrofitting. Compliance with energy codes is determined at permit time, using prescriptive or predictive models, and actual post-construction performance may never even be reviewed. Heating and cooling equipment could be faulty or improperly controlled, with significant energy and financial implications. Under outcome-based energy codes, owners could pursue the retrofit strategy that they decide is most effective for their building and its tenants, but they would be required to achieve a pre-negotiated performance target through mandatory annual reporting. The City of Seattle and the New Buildings Institute have teamed up with the National Trusts’ Preservation Green Lab to pioneer a framework for just such a code, for both new and existing buildings.

Community purchasing power. Neighborhoods interested in renewable energy will increasingly band together to obtain better pricing on materials such as solar panels and on installation costs. The Solarize Portland program was initiated by local neighborhood leaders who wanted to increase the amount of renewable energy generated in Northeast Portland by working together as a community. The program is structured so that the price of solar panel installation decreases for everybody as more neighbors join the effort. Group purchasing creates a 15-25% savings below current prices. This group discount, in addition to current available tax credits and cash incentives, gives participants a significant cost savings. In Philadelphia, the Retrofit Philly program leverages contests between residential blocks to get neighborhoods involved in energy upgrades.

“Grid-aware” appliances fuel convergence of smart grid and smart homes. While many residential smart meters have been installed, the customer interface that will allow homeowners to track energy use more accurately are not yet in place. In the meantime, manufacturers are increasingly introducing appliances that are “grid-aware.” These appliances are endowed with more sophisticated energy management capabilities and timers, offering homeowners machines that monitor and report their own electricity usage and that increase or decrease that usage by remote command. Many machines have timers and can already be manually programmed to run during off-peak hours. These developments will begin forging the convergence of a smart grid infrastructure and the control applications needed to manage energy savings in our buildings and homes.

Accessory dwelling units. Last year we discussed home “right-sizing” as a trend. However, with fewer people moving or building due to financial concerns, many have chosen to stay put in their favorite area and build accessory dwelling units (ADUs). These small independent units, which can be used for offices, studios, or in-law space, are the ideal size for energy savings and sustainable construction. As detached or attached rental units, they help cities increase urban density and restrict sprawl, while allowing homeowners to add value to their property. The cities of Portland, Oregon, and Santa Cruz, California, have waived administrative fees to encourage more ADU construction.

Rethinking of residential heating and cooling. Advances in applied building science in the U.S. and abroad have resulted in homes that are so tightly sealed and insulated that furnace-less, ductless homes are now a reality. The increasingly popular “Passive House” standard, for example, calls for insulation in walls and ceiling that is so thick that the home is actually heated by everyday activity of the occupants, from cooking to computer use. Even in ENERGY STAR-certified homes, builders are now encouraged to bring all ductwork inside the insulated envelope of the house to eliminate excess heat or cooling loss, and to use only small but efficient furnaces and air conditioners to avoid wasting power. Geothermal heating and cooling, where piping loops are run through the ground to absorb warmth in the winter and cool air in the summer, are another option gaining broader acceptance.

Residential grey water use. With water shortages looming in many areas including the Southwest and Southern California, recycling of grey water – any household wastewater except toilet water – is gaining traction. Benefits include reduced water use, reduced strain on septic and stormwater systems, and groundwater replenishment. Although many cities have been slow to legislate on grey water use, some communities have increased the amount of allowable grey water use for irrigation. Systems can be as simple as a pipe system draining directly into a mulch field, or they can incorporate collection tanks and pumps.

Small commercial certification. A total of 95% of the commercial building starts in the U.S. are under 50,000 square feet, but most of the currently certified commercial buildings tend to be much larger. This is in part because of numerous “soft” costs--commissioning, energy modeling, project registration, and administrative time--can be prohibitively expensive for small building owners and developers. To encourage more small commercial projects to go green, alternative certification programs have sprung up, including Earthcraft Light Commercial and Earth Advantage Commercial, which have found significant appeal through fully subscribed pilot programs.

Lifecycle Analysis (LCA). We know quite a bit about the performance of certain materials used in the construction of high-performance homes and commercial buildings, but the industry has just begun to study the effects of these materials over the course of their entire lives, from raw material extraction through disposal and decomposition. Lifecycle analysis examines the impact of materials over their lifetime through the lens of environmental indicators including embodied energy, solid waste, air and water pollution, and global warming potential. LCA for building materials will allow architects to determine what products are more sustainable and what combination of products can produce the most environmentally friendly results.

Source:

www.builderonline.com

The 'Ark' Eco Building of the Future

The housing of the future as envisioned by Russian architect Alexander Remizov could be constructed quickly, withstand environmental disasters, and house 10,000 people at a time. Not bad if you don't mind living in a place that looks eerily similar to a hamster Habitrail. The eco-friendly dome, 'The Ark,' is designed to withstand biblical flood levels and can be built on land or sea.


Ark would be built with pre-fab frame

The Ark would be built with a pre-fab frame made from timber, steel, and high-strength ETFE plastic instead of glass. The foil is recyclable, self-cleaning, lighter, more durable and more economic than glass. The multi-use material is also set up to collect solar rays and rainwater from the roof's surface.


Clear roof allows for plants to grow inside


The Ark can be built to float on water, and can withstand rising tides and floods of biblical proportion.


The basic building starts as a tube-like shape



Then the framework of steel cables is added. The housing can also be constructed in earthquake zones. Its structure of ropes and arches distributes stress from temblors across the building.



For the Ark designed to float, half the building sits underwater.



The building is self-sufficient: The basement can store wind, thermal, and solar energy for up to six months, which can then turn into electricity.

Source: http://slumz.boxden.com/

GREEN BUILDING 101: Indoor Environmental Quality

Feeling good in our homes or offices isn’t just a matter of having a beautiful space. No matter how fabulous your furnishings, a poorly designed indoor environment can literally make you sick. Building green means considering not only the environmental impact of materials and construction, but also the physical and psychological health of the occupants.
The next phase of our series covers Indoor Environmental Quality (IEQ) — one of the criteria of the USGBC‘s LEED-H rating system. IEQ addresses the subtle issues that influence how we feel in a space. It’s not some airy-fairy concept; these are scientifically proven facts. Companies that make the move to green buildings have employees with lower turnover rates, fewer sick days and higher productivity; schools demonstrate higher test scores, lower absenteeism and heightened academic enthusiasm among students. At home, of course, these factors are vital, since the way we feel at home affects every area of our lives.Some can argue that it is not only desirable, but also a fundamental human right to live and work in spaces with healthy indoor environments. Buildings enhance people’s lives when they permit ample air circulation, maintain clean air and comfortable temperatures, and allow individuals to have a sense of control over their own indoor experience.

1) Design a sense of control over personal space.
People generally experience a greater sense of well being when they can make easy adjustments to their immediate space, such as through operable windows, skylights and sliding doors. Particularly in shared spaces, like family homes and offices, it’s important to feel that the indoor environment can meet your own needs. Climate controls designed into multiple rooms can also promote comfort and conserve energy by allowing temperature changes only where needed.Studies show that employees are actually far more productive in an office space that permits awareness of outside conditions. Isn’t it nice to be able to look out on a tree or garden — or better yet to step out for a few minutes for mid-day stress reduction? Various parts of Europe are planning to enact ‘blue-green’ laws, which will entitle all workers to a view of the sky and landscape. Perhaps policy makers in the States could boost the productivity of the American workforce by drawing from these ideas and others described in Towards Sustainable Architecture: European Directives and Building Design.
One of the greatest examples of promoting personal comfort in shared environments can be found in Shigeru Ban’s Naked House (2000), which “gives everyone freedom to have individual activities in a shared atmosphere.” The portable bedrooms sit atop castors, and can be rolled near air conditioning units on cold days or the heaters one cold ones. The house is lit by diffused natural light on all four sides and uses doors instead of windows to turn the bathroom (above) into a covered breezeway for natural ventilation and light. Ban’s “radical” design won Best House in the World at the World Architecture Awards.

The wide open indoor-outdoor desert house from Marmol Radziner

2) Help buildings breathe better.
Spaces that are closed up like hermetically sealed boxes can cause pollutants to accumulate to levels that can pose health and comfort problems and contribute to Sick Building Syndrome. Instead, naturally ventilate spaces as much as possible without compromising reasonable humidity levels. Variations in temperature are also important — spaces kept at a constant temperature do not mimic our natural internal fluctuations, and can cause a sense of malaise.The building envelope can provide cross ventilation through narrow floor plans and openings in floors and ceilings that allow vertical circulation. Solar chimneys and other types of stack ventilation draw heat up and move air even when there is no breeze outdoors.When using mechanical ventilation, make sure that the “exchange rate” is high, meaning that the majority of air in a space is coming from the outdoors, thereby reducing the amount of pollutants inside. Fan-powered ventilation is recommended to remove air from single rooms, such as bathrooms and kitchens, where the pollutant levels from human activity,cleaning agents and mold are high. Air handling systems use fans and ductwork to constantly remove indoor air and distribute filtered and conditioned air to strategic spaces throughout a building.

reSEAT manufactures their furniture with compositeboards made of discarded organic matter and soy.

3) Reduce indoor air quality problems at the source.
Identify potential sources of indoor pollution that stem from design choices, existing conditions, and lifestyle activities. Moving into a new home, remodeling a space, and bringing in new furniture can expose inhabitants to abnormally high levels of volatile organic compounds (VOCs), which are the toxic gases, such as formaldehyde, released from everyday materials that are responsible for contributing to cancer, asthma, fatigue, and other ailments. Formaldehyde is found in household products and fuel-burning appliances, “permanent-press” clothing and draperies, and many paints, coatings and glues. The most significant source is pressed wood products for cabinetry, furniture, and subflooring.A smart designer will specify paints, adhesives, sealants, furniture, wood sealants and other products with a low or no VOC content to help ensure the health of the occupants. Last week’s Green Building 101 segment provided myriad examples of materials and resources to help create a healthy environment.
To control pollution already existing in a house, test basements for radon, and other spaces throughout for excessive dampness and mold. Prevent mold growth, which also contributes to asthma, fatigue, and other ailments, by preventing the accumulation of water at drainage systems and at areas where mechanical ventilation condensates. Also inspect the house for leaky pipes, windows, skylights and other areas to eradicate problems from mold. The Environmental Protection Agency’s website contains strategies for improving the quality of indoor air in your home.

4) Eliminate poisons and beware of harmful pest control substances
Use non-chemical methods of pest control when possible. If the roach won’t take to being led outside with a nudge from a newspaper, then be sure to ventilate the space well after using a pesticide. Natural pesticides have fewer harmful side effects and break down more quickly in the environment than synthetic chemicals do. Don’t forget that they are still poisons and harmful to humans. Try Poison-Free Ant & Roach Killer, which uses food-grade Mint Oil to kill bugs in seconds. It’s also a good habit to frequently wash indoor plantsand pets, which attract bugs indoors.

Source: inhabitat

Dr. Andrew Marsh PhD, B. Arch. (Hon)

Andrew is a graduate architect who specializes in the computer simulation of building performance, working as an environmental consultant, researcher and lecturer. He is a principal of Square One - Environmental Design Website compiled with Caroline Raines B. Arch. (Hon), B. Env. Des. and the Welsh School of Architecture at Cardiff University. This site provides free information for architects, building designers, students and anyone else interested in energy efficient and sustainable design.

In the following website, you can find some of his excellent simulations:

http://andrewmarsh.com

7 More London (First BREEAM ‘outstanding’ in London)

7 More London is one of the UK's first speculative offices to achieve a top BREEAM rating at design stage.

There is a new landmark on the banks of London’s River Thames. Alongside Tower Bridge and across the river from the Tower of London is a new office building called, modestly, 7 More London. Despite its unassuming title this conventional-looking corporate building is significant because it is one of the first major speculative office schemes in the UK to have been awarded a BREEAM Outstanding rating at design stage. It is now working to the target of following up the interim rating with a full rating post-construction.

Description

7 More London is the final and largest building to be constructed under the masterplan for the More London site. The 10 storey, 60 000 m² building incorporates 48 000m² of office space located above ground floor retail units. Construction of the building’s shell is complete; its glazed, symmetrical wings of offices open out to embrace the river revealing a hollow circular drum, housing the reception, at its core. Three curved bridges connect these two wings at levels two, five and eight, while at the rear the building’s southern elevation drops to seven storeys to respect the existing buildings along Tooley Street. Inside work is underway to fit out the offices ready for the building’s 6000 occupants, which will have moved in to their new home by May 2011.

The story of how 7 More London became one of the UK’s greenest office buildings started four years ago, when PricewaterhouseCoopers’ (PwC) decided to lease the ten storey office in order to consolidate its London operations. At the time, the building was still on the drawing board so it was regarded by PwC as having the potential to meet the firm’s sustainable vision. “We wanted this building to dispel some of the myths in the real estate world that occupiers are not interested in sustainable buildings, the so called ‘circle of blame’,” says Paul Harrington, real estate director at PwC. He says occupiers do want good sustainable buildings because “sustainability is good business practice”.

Sustainability was also seen as a differentiator between PwC and its competitors and Harrington was aware that most of the questions on the firm’s website relating to the move to new offices concerned what the organisation would be doing to enhance sustainability in its new offices. “The drive for sustainability was from the top down and the bottom up,” explains Harrington.

At the time PwC decided to lease the building it had a planning requirement to achieve a minimum environmental rating of BREEAM Very Good (2006). Accordingly, PwC pushed the developer and its design team along with PwC’s fit-out designer BDP to target the highest level of environmental performance attainable at that time, BREEAM Excellent (2006). As work on the building’s engineering design commenced, however, details began to emerge of an upgrade to BREEAM and the release of BREEAM Offices 2008. This was a major blow to PwC’s vision because the changes included the addition of a new elite rating of BREEAM Outstanding to the classification system. The result of which was that as it stood, PwC’s new building would no longer be the sustainable differentiator it wanted.

PwC upped the ante and set a target for the building to achieve BREEAM Outstanding (2008), under the revised criteria. “This is a building for the future and a building that will last us for the next 20 years so it would seem crazy not to go for the ultimate category,” says Harrington. To achieve this rating the design would have to achieve a minimum of 85 out of a possible 100 environmental points. This was uncharted territory.

To stand any chance of getting close to the threshold of 85 points, collaboration between the developer’s and tenant’s design teams was essential so that tenants and developers design teams grasp every opportunity to tease every last credit out of the scheme. “It was important that both project teams were involved, without this joint effort we would never achieve what we wanted,” Harrington says.

Learning points

“The key to attaining the Outstanding rating was to start with a good base building;” says Stephen Runicles, environmental design director at BDP. Fortunately Roger Preston and Partners’ design for the base building already included many low energy and environmentally beneficial features. This included:

· A high performance building envelope, based on an argon-filled, low transmission glazing system fitted with extensive shading to minimise solar heat gains.

· A biofuel based tri-generation system to generate heat, power and cooling using absorption chillers (CCHP). The specification of the CHP engines was enhanced to enable them to run on any biofuel including used cooking oil. The system incorporated two engines each capable of developing 385kW of electricity along with 400 kW of heating and 416 kW of cooling.

· Plate heat exchangers were added to CCHP to units to increase the use of waste heat and extend the CCHP unit’s run time to enable it to provide up to 25% of the buildings total electricity demand.

· Also included in Roger Preston’s base-build design was a solar thermal hot water supply to the core’s toilet pods and a heat recovery ventilation system.

· To squeeze every extra credit out of the design a regenerative braking system was incorporated into the building’s 16 lifts.

· PwC were helped in their task of grabbing BREEAM points by the building’s structural designers Arup, who succeeded in using 80 per cent recycled aggregate for the first time in the building’s concrete structure; an achievement which merited the award of the first ever BREEAM point for innovation.

On the office floors, the enhancements to BDP’s design to achieve BREEAM Outstanding saw:

· The office fan-coil units replaced by active chilled beams. The amount of fresh air supplied to these units is minimised by linking it to CO₂ concentration in the offices.

· The building’s electric perimeter heating was replaced by low-grade hot water heating system fed from heat recovery units added to the building’s roof-mounted chillers. The units supply low grade hot water at 45°C but the addition of the heat recovery system also improved chillers’ efficiency by 35 per cent and earned the design team another BREEAM point for innovation.

· In addition, a sophisticated control system was also developed with extensive sub metering to monitor cooling, heating, power and lighting loads on a zone by zone basis.

· The offices are also being fitted with an ultra efficient, high frequency, fully-programmable low-energy lighting system which is daylight-linked. The system is IP addressable which will allow it to be controlled by the building’s occupants via their PCs, within strict boundary conditions, and will incorporate time clock control and presence detection for out of hours working.

· In hospitality areas, restaurant, cafes and corridors BDP has opted for high efficiency LEDs to help reduce maintenance and save energy

Outcomes

“We’ve looked sensibly at what we’ve invested in,” says Harrington. As a result there were some technologies PwC did not utilise because their payback would have been over 50 years. “Some technologies have a payback of up to 15 years, but that still makes good business sense on the basis of a 20 year lease,” explains Harrington. “You have to talk commercially about sustainability; the days of windmills on roofs are gone, we now need to deliver things that are practical and cost effective,” he says.

The building has even been future-proofed to allow further environmental enhancements when these become cost effective. This includes strengthening the building’s structure in key areas to enable rainwater storage tanks to be installed in the future. There is also provision for the future installation of a solar electric array on the building’s roof – should it become cost effective for PwC to do so.

The good news for the design team was that the building succeeded in achieving a BREEAM Outstanding rating based on its design. It was also awarded an EPC A rating. According to Runicles the building will achieve “a 70% improvement in CO2 emissions over current (2006) Building Regulations Part L2.

“When we set out we wanted to demonstrate that BREEAM Outstanding could be achieved at a sensible price,” says Harrington. The good news for PwC is that the estimated cost increase of taking the building from BREEAM Excellent to BREEAM Outstanding was minimal. “We estimate it cost at £2.25 per square foot on the base price to achieve BREEAM Outstanding, which proves that good sustainable buildings need not cost that much more money if they are properly planned and specified,” he says.

Having achieved BREEAM Outstanding for the design, the next challenge is to ensure construction waste targets are met and the scheme gets an Outstanding rating under the BREEAM post-construction review. “We’re not being complacent, we’re working hard with the contractors to ensure that they meet these very challenging targets,” says BDP’s Runicles.

The design team scored 8 out of a possible maximum of 10 innovation credits to achieve BREEAM Outstanding including:

- The building becomes a learning resource by displaying environmental performance data to staff and visitors

- 80 per cent recycled aggregate used in the building’s concrete

- Exemplar performance under the Considerate Constructors Scheme

- Recovering heat from the chillers that would normally be rejected to atmosphere and using this heat in the perimeter heating system

- Water sub-metering

- Involvement of expert accredited professional BREEAM advice from pre-stage C (2 credits)

- Use of multi-fuel CHP engines

Project Team Box: Shell and Core

Client: More London Developments

Architect: Foster + Partners

M&E consultant: Roger Preston & Partners

Structural engineer: Arup

Construction manager: Mace

Project team box: Tenant fit out

Client: PricewaterhouseCoopers

M&E and interior design: BDP

Project and cost management: Turner & Townsend

Fit out contractor: Overbury

Source: http://www.building4change.com

Introduction to Energy Efficient Building Design

1. INTRODUCTION

1.1 Importance of Building Energy Efficiency

• Buildings are significant users of energy and building energy efficiency is a high priority in many countries.
  
  
• Efficient use of energy is important since global energy resources is finite and power generation using fossil fuels (such as coal and oil) has adverse environmental effects.
  

• The potential for energy savings in the building sector is large.
  
  

1.2 Assumption

• Energy efficient building design is location-dependent. The local climate must be considered when selecting appropriate design strategies.
  
  
• A cooling-dominated climate is assumed here. However, some of the general principles are also applicable to other climate types.

2. BASIC PRINCIPLES

2.1 Climate and Site

• Climate has a major effect on building performance and energy consumption. Energy-conscious design requires an understanding of the climate.
• Buildings will respond to the natural climatic environment in two ways:
• Thermal response of the building structure (heat transfer and thermal storage).
• Response of the building systems (such as HVAC and lighting systems).
• To gain the maximum benefits from the local climate, building design must "fit" its particular climate.
• When faced with unfavourable climatic conditions, optimal siting and site design may solve all or part of the problems. Site elements to be considered include:
• Topography - slopes, valleys, hills and their surface conditions.
• Vegetation - plant types, mass, texture.
• Built forms - surrounding buildings and structures.
• Water - cooling effects, ground water, acquifiers.
• The six important aspects of architectural planning which will affect thermal and energy performance of buildings are:
• Site selection
• Layout
• Shape
• Spacing
• Orientation
• Mutual relationship
• Architectural and landscape designs should be closely integrated. If possible, should provide wind breaks in cold winter and access to cooling breezes in summer.

Figure 1 - Wind control in site analysis

2.2 Building Envelope

• Elements of the building envelope (= "protective skin"):
• Walls (exterior)
• Windows
• Roof
• Underground slab and foundation
• Three factors determining the heat flow across the building envelope:
• Temperature differential
• Area of the building exposed
• Heat transmission value of the exposed area
• The use of suitable thermal mass and thermal insulation is important for controlling the heat flow. Remember, the envelope components will respond "dynamically" to changing ambient conditions.
• Some people also consider the "embodied energy" (include energy for producing and transporting) of building materials when making the selection.

Figure 2 - Building envelope design that combines passive solar, daylighting and organic horticulture

2.3 Building Systems

• Heating, ventilation and air-conditioning (HVAC) systems are installed to provide for occupant comfort, health and safety. They are usually the key energy users and their design is affected by architecture features and occupant needs.
• While being energy efficient, HVAC systems should have a degree of flexibility to allow for future extensions and change.
• To achieve optimum energy efficiency, designers should evaluate:
• Thermal comfort criteria
• Load calculation methods
• System characteristics
• Equipment and plant operation (part-load)
• Lighting systems is another key energy user and additional cooling energy will be required to remove the heat generated by luminaires.
• Energy efficient lighting should ensure that:
• Illumination is not excessive.
• Switching is provided to turn off unnecessary light.
• Illumination is provided in an efficient manner.
• General design strategies for lighting design:
• Combination of general and task lighting.
• Electric lighting integrated with daylight.
• The use of energy efficient lamps and luminaires.
• Use light-coloured room surfaces.
• Other building services systems consuming energy include:
• Electrical installations
• Lifts and escalators
• Water supply systems
• Town gas supply system

3. Technologies

3.1 Passive Cooling and Sun Control

• Passive systems - internal conditions are modified as a result of the behaviour of the building form and fabric.
  
  
• General strategies for passive heating and cooling:
  
  
• Cold winters - maximise solar gain and reduce heat loss.
• Hot summers - minimise solar gain and maximise heat removal.
• Correct orientation and use of windows.
• Appropriate amounts of thermal mass and insulation.
• Provision for ventilation (natural).
  
  
• Strategies for shading and sun control:
  
  
• External projection (overhangs and side fins).
• External systems integral with the window frame or attached to the building face, such as lourves and screens.
• Specially treated window glass, such as heat absorbing and reflecting glass.
• Internal treatments either opaque or semi-opaque, such as curtains and blinds.
  
  
• For hot and humid climate like Hong Kong, extensive shading without affecting ventilation is usually required all year round. Shading of the east and west facades is more important.
  

3.2 Daylighting

• Daylight can be used to augment or replace electric lighting. Efficient daylighting design should consider:
  
  
• Sky conditions
• Site environment
• Building space and form
• Glazing systems
• Artificial lighting systems
• Air-conditioning systems
  
  
• The complex interaction between daylight, electric lights and HVAC should be studied carefully in order to achieve a desirable solution.
  
  

Figure 3 - Daylighting design in an atrium

• Advanced window technologies have been developed to change/switch the optical properties of window glass so as to control the amount of daylight. There are also innovative daylighting technologies now being investigated:
  
  
• Light pipe systems
• Light shelves
• Mirror systems
• Prismatic glazing
• Holographic diffracting systems
  
  

3.3 HVAC Systems

• Energy efficiency of many HVAC sub-systems and equipment has been improved gradually over the years, such as in air systems, water systems, central cooling and heating plants.
  
  
• Energy efficient HVAC design now being used or studied include:
  
  
• Variable air volume (VAV) systems to reduce fan energy use.
• Outside air control by temperature/enthalpy level.
• Heat pump and heat recovery systems
• Building energy management and control systems.
• Natural ventilation and natural cooling strategies.
  
  

Figure 4- Waste heat recovery in a doule-bundle chiller plant

• Thermal storage systems (such as ice thermal storage) are also being studied to achieve energy cost saving. Although in principle they will not increase energy efficiency, they are useful for demand-side management.
  
  

3.4 Active Solar and Photovoltaics

• Solar thermal systems (active solar) provide useful heat at a low temperature. This technology is mature and can be applied to hot water, space heating, swimming pool heating and space absorption cooling.
  
  
• The system consists of solar collectors, a heat storage tank and water distribution mains. An integrated collector storage system has also been developed recently to eliminate the need for a separate storage tank.
  
  

Figure 5 - Schematic of a typical solar hot water system

• Photovoltaic (PV) systems convert sunlight into electricity using a semi-conductor device. The main advantages of PV systems include:
  
  
• Reasonable conversion efficiencies (6-18%).
• PV modules can be efficiently integrated in buildings, minimising visual intrusion.
• Their modularity and static character.
• High reliability and long lifetime.
• Low maintenance cost.
  
  
• In practice, PV technology can be used for central generation or building-integrated systems (BIPV). The systems can be of the standalone type, hybrid type or grid-connected type. Although the cost of PV is still high at present, it may become cost-effective in the hear future.
  
  

Figure 6 - Grid-connected solar photovoltaic system

4. Evaluation Methods

4.1 Bioclimatic Design

• The integration of design, climate and human comfort -- the bioclimatic approach to architectural regionalism -- was first proposed in mide-1950s by Victor and Aladar Olgyay.
  
  
• Their intention was to highlight the belief that architectural design should begin with understanding of the physiological needs of human comfort and take advantage of local climatic elements to optimise these requirements naturally and efficiently.
  
  
• Building design itself is conceived as a natural energy systems that restores environmental quality to its site.
  
  
• The aim is to creat a supportive and productive environment that ultimately can contribute to sustaining the regional and global environment.
  

4.2 Building Thermal and Energy Simulation

• Nowadays, building energy design often require the analytical power to study complicated design scenerio. Computer-based building energy simulation will provide this power and allow greater flexibility in design evaluation.
  
  
• The simulation method is based upon load and energy calculations in HVAC design. The purpose is to study and determine the energy characteristics of buildings and their building systems.
  
  
• The cost effectiveness of any energy conservation measures will be a compromise between initial, maintenance and energy costs. Simulation techniques can provide the tools for assessing different design options based on their energy performance and life cycle costs.
  

4.3 Building Energy Audits

• Building energy auditing can be defined as "measuring and recording actual energy consumption, at site, of a completed and occupied building (expressed in units of energy, not monetary value); fundamentally for the purposes of reducing and minimising energy usage".
  
  
• Energy audits identify areas where energy is being used efficiently or is being wasted, and spotlight areas with the largest potential for energy saving. They are useful for establishing consumption patterns, understanding how the building consumes energy, how the system elements interrelate and how the external environment affects the building.
  
  
• There are different approaches to conducting a full building energy audit, but the following stages are often adopted:
  
• Stage 1 - An audit of historical data
• Stage 2 - Survey
• Stage 3 - Detailed investigation and analysis
  
  
• A proper energy audit is useful for more than energy conservation goals. Energy audits can be employed to assist in areas such as:
  
• Establishment of data bank and consumption records.
• Estimating of energy costs.
• Determining of consumption patterns and utility rates.
• Establishment of an operational overview.

5. Conclusions

• Building energy design challenges building designers to think about climate, orientation, daylighting, and the qualities of environment as part of the initial design conception.
  
  
• It also requires the architectural and engineering disciplines to work as a team early in the design phase and to conceptualise the building as a system.
  
  
• Architects and engineers who incorporate energy design concepts and methods into their design projects can play a significant role in reducing energy consumption and achieving sustainable energy structure for our society.

Source:

http://www.arch.hku.hk