Choose the Proper HVAC Equipment
Newly updated software published by the Portland Cement Association (PCA) allows builders to estimate heating and cooling system capacities for energy-efficient single-family concrete homes. The software calculates the system capacities based on the house dimensions, construction materials, air infiltration, location (U.S., Mexico, and Canada), and thermostat set point. To account for the thermal mass imparted by concrete walls, this software uses hourly weather data for a typical year.
The inherent energy-saving properties of insulated concrete walls often result in heating, ventilation, and air conditioning (HVAC) equipment being downsized by as much as 15% to 40% in concrete homes in comparison to identical wood-frame homes. Current widely used HVAC-sizing methods such as Manuals J and the ASHRAE Load Calculation Method do not account for the thermal mass, high levels of insulation and/or low air infiltration of the insulated concrete walls. This omission, and the fact that many builders and HVAC contractors' size HVAC equipment based on a "rule-of-thumb" developed for wood-framed homes that equate equipment size with square footage of living space, results an the installation of an inefficient HVAC system that typically is oversized.
An oversized HVAC unit will have a higher initial cost than a correctly sized system and consumes more energy than necessary. In addition, an oversized system will have a shortened "on" time, which can lead to larger temperature swings and reduced thermal comfort. Air conditioning systems with short "on" times do not remove enough moisture from the indoor environment, which can increase the probability of occupant respiratory problems.
The PCA software uses energy modeling software that is more representative of actual conditions in which the HVAC system will be operating. MS Excel version 97 or later required for operation of the program. Check out www.cement.org/bookstore for more information.
The New American Home 2009
The New American Home (TNAH) 2009 showcases the exceptional savings concrete systems provide homebuilders and homeowners. The exterior structural walls and basement foundation walls are built with insulating concrete forms, which sandwich concrete between two insulating layers of foam.
As the official show home of the National Association of Home Builders, the house debuts at the International Builders' Show in Las Vegas, Jan. 20-23, 2009. In addition to the high R-valued derived from the foam insulation, the thermal mass of the concrete walls helps the home achieve its high level of energy efficiency. The U.S. Department of Energy's Building America program estimates the home uses approximately 70% less energy for heating and 61% less energy for cooling than a comparably sized wood-frame home in a similar climate.
This level far exceeds the ENERGY STAR requirement of being at least 15% more energy efficient than a typical home. ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy designed to save money and protect the environment through energy efficient products and practices. The home is also applying for Emerald status under the newly established NAHB Green Building Standard.
To learn more about TNAH 2009, visit www.buildersshow.com
Builders Urge Congress About Housing Stimulus
The National Association of Home Builders (NAHB) launched an effort to make housing a centerpiece of the massive economic stimulus package that lawmakers are expected to complete by mid-February. More than 80 builders from across the country converged on Capitol Hill this January to meet with the congressional leadership and key members of the banking and tax writing committees to convey the message that a housing stimulus is urgently needed and that restoring demand for housing is the fastest and most effective way of reviving the economy.
The key ingredients to the recovery plan call for Congress to support enhancements to the home buyer tax credit, to provide below-market interest rates on 30-year fixed-rate mortgages, and to continue foreclosure prevention measures such as those advocated by Federal Deposit Insurance Corp. chairman Sheila Bair. Under Bair's plan, the federal government would provide $24 billion in loan guarantees that could help as many as 1.5 million home owners modify their existing mortgages and avoid foreclosure.
This year alone, NAHB chief economist David Crowe says the plan would result in 200,000 additional new home sales, 1 million more existing home sales, and a boost in expected housing starts from 649,000 to 908,000, on par with last year's level. In addition, the plan this year would create more than 539,000 jobs, generating $26 billion in wages and salaries, $21 billion in business income, and $28 billion in federal, state and local tax revenues.
A temporary, expanded home buyer tax credit is needed to reduce excess inventory and encourage fence sitters to enter the market. The Fix Housing First legislative proposal calls on Congress to enact a stimulus plan that would reduces mortgage interest rates to as low as 2.99% on 30-year fixed-rate conventional loans purchased between Jan. 1, 2009 and June 30, 2009. The interest rate would be 3.99% for contracts that close between July 1, 2009 and Dec. 31, 2009.
At the same time, lawmakers need to make the current $7,500 home buyer tax credit much bigger and better, eliminating its current recapture provision and making it available to all purchasers. The coalition is calling for a credit amounting to 10% of the home's price, capped at 3.5% of local FHA loan limits. This would range between $10,000 and $22,000.
To learn more about the coalition, go to www.fixhousingfirst.com.
EPA Proposes Stricter Stormwater Standards on Construction
On November 28, 2008, the Environmental Protection Agency (EPA) proposed a rule under the Clean Water Act entitled "Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category." The proposed non-numeric effluent limitations guidelines (ELGs) would require contractors, developers, and others conducting land-disturbing activities to implement specific minimum best management practices (BMPs) for erosion control, sediment control, and pollution prevention. Certain sites could be required to implement stormwater treatment processes in addition to BMPs in order to meet the new standards, and other large sites may have to meet numeric turbidity limits. Treatment and numeric limits would be a significant change from existing standards, which focus chiefly on BMPs. The proposed ELGs are intended to work in concert with state and local programs, establishing minimum requirements or a "floor" that would be applicable nationally. The ELGs, if promulgated, will be applied to construction and development sites as EPA, states, and tribes incorporate the new requirements into general and individual stormwater discharge permits. EPA has requested public comment on the proposed rule until Feb. 26, 2009.
In addition to requiring BMPs, the proposed ELGs mandate that construction sites disturbing 10 or more acres at a time also would be required to install sediment basins or approved alternatives to treat stormwater discharge. Also, certain large sites of 30 acres or more located in areas with high rainfall and with high clay content soils would have to comply with a numeric limit on the allowable level of turbidity. The turbidity limit would be set to remove fine-grained and slow-settling or nonsettleable particles contained in stormwater, since particles such as clays and fine silts contained in stormwater discharges typically cannot be effectively removed by conventional stormwater best management practices. To achieve this numeric limit of turbidity, many developers may have to treat and filter the stormwater discharge at their construction sites.
Industry officials have voiced concern over the proposed numeric discharge limit that potentially requires installation of expensive control technologies at large construction sites. In addition, some industry and trade groups oppose numeric standards generally in the context of stormwater regulation, preferring BMPs as more flexible and as adding less to the bottom line on construction projects compared to complying with numeric standards.
EPA estimates that the proposed rule will reduce the amount of sediment discharged from construction sites by up to 27 billion pounds each year, at a projected annual cost of $1.9 billion. EPA says that the benefits from the proposed rule include better protection of drinking water supplies, improvements in aquatic environments, and reduced need for dredging of navigation channels.
Visit www.cfawalls.org for more information.