Building Features that Improve Energy Efficiency

Building Features that Improve Energy Efficiency

Energy efficiency projects often focus on upgrading mechanical and electrical systems in existing buildings. However, the opportunity to save energy starts from the design and construction phase. There are many building features that improve efficiency, and their benefits are permanent.

Energy saving measures are also effective in existing buildings, but a finished construction offers less flexibility. Upgrades to the building envelope are particularly expensive, since they involve demolition and rework. In other words, the best opportunity to maximize building efficiency is before starting construction.

There are many ways to improve building efficiency, but HVAC and lighting represent the largest share of energy costs. Measures that target these systems are the most effective, and this applies for both equipment upgrades and construction features.

• A building can improve its efficiency by maximizing daylight. Even LED lighting has an operating cost, while natural lighting is delivered for free.
• A high-performance building envelope is also fundamental for energy efficiency, since the workload on HVAC installations is reduced.

When a building is designed with natural lighting, effective insulation and airtightness, the energy efficiency benefits extend throughout its service life. 

Using Natural Lighting Effectively

Sunlight is free, while artificial lighting will always have energy costs. However, incorrect use of natural lighting brings two negative consequences: glare and solar heat gain.

• The sun causes glare when it is directly visible for occupants, or when reflected on some surfaces. Glare causes visual discomfort and distraction, and long-term exposure is harmful for human vision.
• Solar heat gain is detrimental for energy efficiency during summer, since it increases the workload on air conditioning equipment.

When natural lighting is well designed, it prevents glare and minimizes solar heating. The combination of skylights and well-placed windows can greatly reduce lighting expenses in a building.

Daylight harvesting is a promising concept, which consists of controlling lighting fixtures based on the available daylight:

• Unless the full output of a lighting system is required, it is dimmed down in response to daylight. 
• At times when natural lighting is enough for the needs of a building, the lighting fixtures are deactivated automatically.
• If an LED lighting upgrade is carried out, the savings can be enhanced with daylight harvesting.

Designing an Efficient Building Envelope

An efficient building envelope minimizes heat transfer in both directions, preventing heat gain during summer and conserving heat during winter. An airtight construction is also necessary, since air leaks can transport heat into and out of a building.

An existing building envelope can be improved, but the best results are achieved in new constructions. For example, insulated concrete forms (ICF) can drastically improve the thermal performance of a building. However, they are unfeasible in finished constructions, since they are embedded on walls and other building elements.

Triple-pane windows with low-emissivity coating can also improve insulation. They achieve a quicker payback period in new projects, since they only represent a cost increase with respect to conventional windows. On the other hand, a window upgrade for an existing building requires extra labor to dismount the existing ones. The cost-benefit analysis is also based on the full window price, since the cost of the original windows has already been paid.

Natural ventilation can be achieved if a building design allows large-scale air circulation by convection. A common solution is using an atrium to remove air, combined with air intakes for every level. Of all construction features that improve efficiency, natural ventilation is the most challenging for existing buildings, since the entire construction must be optimized.

As the performance of the building envelope increases, heating and cooling requirements decrease. As a result, the HVAC installations can be designed with a reduced capacity. This not only reduces the initial investment, but also operating costs.

Michael Tobias, PE, LEED AP, CEM.

Michael Tobias is the founder and principal of Chicago Engineers, an Inc 5000 Fastest Growing Company in America. He leads a team of 30+ mechanical, electrical, plumbing, and fire protection engineers from the company headquarters in New York City; and has led over 1,000 projects in Chicago, New York, New Jersey, Pennsylvania, Connecticut, Florida, Maryland and California, as well as Singapore and Malaysia. 

About Author:

I am Thomas Britto here to share my experiences in the civil engineering field to all my readers.Today many students are struggling to buy books at high prices. So I decided to start a blog and share my experience and knowledge with all my readers.

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