Making a building more sustainable while completing the retrofit could attract more higher-paying tenants, which would cause a greater appreciation by the time the owners plan to sell. Properties with Energy Star certification have sold for 2-5% more than buildings without such certification.
Len Calderone for | AltEnergyMag
Existing buildings account for most of the energy used in the building sector, whereas new buildings use only a small percentage of energy. The energy use in commercial buildings is predicted to increase every year for at least two decades. Therefore, it is important to retrofit existing buildings to increase energy savings. This endeavor is very complicated with many considerations, such as maintaining historic features to controlling costs.
The U.S. and China uses 35% of all of the world's energy with China surpassing the U.S. to become the world’s largest energy consumer.
In the U.S., approximately 86% of current building construction expenditures are for the renovation of existing buildings while the remainder is for new construction. An estimated 150 billion square feet of existing buildings, which is about 50% of the entire building stock, will be renovated over the next 30 years.
Energy efficiency planning depends on the scale of opportunity for energy efficiency improvements in existing buildings. For most office buildings energy cost is $2–3 per square foot per year. Healthcare properties are one of the most expensive types, usually at $11. A typical building can cut energy use by up to 15% by implementing no and low cost measures and over 45% by implementing deeper retrofit measures. Such retrofit projects will reduce operating costs, and improve occupant comfort with a host of other benefits.
A building doesn’t have to be new to be efficient. Building owners are retrofitting buildings, converting them into archetypes of sustainability. While most building owners still follow individual technology improvements, smart owners package energy saving technologies to get serious savings through lower energy consumption and operating costs. Fundamentally, the improvements are paid for through energy savings over time.
A building can often be retrofitted for a lower cost than a new building. To accomplish this it's important to review the heating and air conditioning system, as well as lighting. The goal should be to create a high-performance building that ensures all of the design concepts are met. By accomplishing the design objectives, the building will be less costly to operate, increase in value, last longer and contribute to a healthier and more productive environment for the workers.
To reach optimum retrofit goals many factors must be considered. Energy and water systems should be upgraded to minimize consumption. During the retrofit, evaluation of where the employees work must be made, and then the use the daylight, HVAC and lighting should be maximized based on the tasks and functions of the occupied space. Natural ventilation and fresh air are alternatives that would reduce heating and air conditioning. Solar shading devices for windows will help reduce energy consumption, or replace existing windows with insulated windows. Insulated windows work well in high noise areas.
A cool or green roof could be cost-effective and help with rain runoff. A cool roof’s surface is painted with material that reflects part of solar radiation. As it can also reflect solar reflection in winter, heating energy consumption is decreased.
A green roof is covered by soil, which increases heat insulation through photosynthesis, transpiration, and shade against solar radiation. The soil itself provides thermal storage and retains water, allowing heat to be carried away through water evaporation. High-quality roof materials are needed to prevent structural failure and water permeation, which will increase the initial cost. Non-soil plant roofs replace soil with sawdust, rock wool or silica. This kind of roof reduces roof load and also significantly improves heat-insulation performance, reaching three times of that of soil plant roof.
To ensure that a newly retrofitted building continues to perform as designed, the operation of the building needs to be tracked on a methodical basis. To help with this, smart meters and sub-meters are used to monitor real-time consumption, demand and accountability. Sub-meters help to monitor the electrical consumption of individual pieces of equipment within a building. Green cleaning products and methods should also be used.
The use of exterior insulation is an effective way to enhance the overall thermal resistance of wall construction. Exterior insulation has other advantages, such as enhanced water management and increased air tightness of the building. Exterior insulation of 2- 8" will be needed on existing masonry walls, while wood furring strips should be used on wood framed walls.
In the past, retrofits of buildings typically involved the filling of framed cavity walls with insulation. The amount of insulation that could be used was limited by the depth of the existing stud cavity in wood framed walls. For masonry walls, the insulation material, usually fiberglass, mineral fiber or cellulose, is determined by the strapping depth.
To overcome these limitations, contractors add insulation to the exterior of existing buildings and achieve higher effective R-values. The benefits of this approach go beyond the added thermal resistance by increasing the building's durability and air tightness. Some of the materials used are expanded polystyrene (EPS) board thin plaster, EPS powder particle, EPS board in-situ concrete, EPS steel wire frame plate in-situ concrete, mechanical fixed EPS steel wire frame plate, XPS board thin plaster, polyurethane spray, or rock wool board. Among these systems, the greatest advantage of EPS board's external thermal insulation system is its low water absorption, which is around 3 percent and its long life.
Making a building more sustainable while completing the retrofit could attract more higher-paying tenants, which would cause a greater appreciation by the time the owners plan to sell. Properties with Energy Star certification have sold for 2–5% more than buildings without such certification. A deep energy retrofit can significantly increase the building efficiency and certainly achieve Energy Star certification. Achieving an Energy Star rating in the high 90s would afford the added advantage of enhanced community standing and marketing for the building. Therefore, a building owner should begin the course of action to start a deep energy retrofit to achieve a high Energy Star rating.
The Building Technologies Office of energy.gov provides resources that allow planners, designers, and owners to focus on energy-use goals from the first planning stages through post-retrofit monitoring. The Advanced Energy Retrofit Guides outline how to conduct an energy efficient retrofit. Energy Modeling Software helps identify the most impactful measures through simulations. And the Technology Portal can be accessed to make fact based procurement decisions during a retrofit.
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Len Calderone - Contributing Editor
Len contributes to this publication on a regular basis. Past articles can be found in the Article Library and his profile on our Associates Page
He also writes short stores that always have a surprise ending. These can be found at http://www.smashwords.com/profile/view/Megalen.
The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag
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