Shapiro I.,Taitem Engineering
ASHRAE Journal | Year: 2011
A study was conducted to examine the efficiency of energy audits and the measures that can be taken to improve their outcomes. An audit had to have an improvement with savings more than twice as high as reasonable. The criterion for this problem was for a cost estimate to be less than half what might be reasonable for a specific improvement. The energy audit that recommended the long-payback wind turbine missed such common improvements as attic insulation, air sealing, lighting controls, and laundry improvements. Audits in single-family residential buildings are more likely to have problems, averaging almost 8.1 out of 10 types of problems per audit, compared to audits in commercial buildings that averaged only 4.6 types of problems per audit. Nine out of 10 common problems are evident in over 50% of energy audits, and the two most common problems appear in almost 80% of energy audits. The two biggest problems are unfortunately complementary.
Shapiro I.M.,Taitem Engineering
ASHRAE Journal | Year: 2012
Small office buildings run the risk of being overlooked and under served for energy improvements because of their size. Common traits between small and large offices include their main space types: primarily desk/office space, but also conference rooms, storage/filing, kitchenettes and break rooms, bathrooms, corridors, stairwells, copy/print areas, and computer rooms. Small office buildings typically do not have energy management systems, so control improvements need to be examined in a different way than for big buildings. Small office buildings also often use residential HVAC equipment, or small commercial equipment such as packaged rooftop units, almost all of which are direct-expansion cooling systems. Small offices also often tend to be integrated as part of a mixed-use building, for example, as one floor of an apartment building, or as one section of a strip mall. Small offices are also often just old houses, with features such as pitched roofs and basements. This brings us back to the importance of envelope energy losses and improvement opportunities, as well as to the important emerging improvements relating to reducing distribution losses.
Varshney K.,Taitem Engineering |
Poddar K.,Indian Institute of Technology Kanpur
Theoretical and Applied Climatology | Year: 2011
Accurate predictions of turbulent characteristics in the atmospheric boundary layer (ABL) depends on understanding the effects of surface roughness on the spatial distribution of velocity, turbulence intensity, and turbulence length scales. Simulation of the ABL characteristics have been performed in a short test section length wind tunnel to determine the appropriate length scale factor for modeling, which ensures correct aeroelastic behavior of structural models for non-aerodynamic applications. The ABL characteristics have been simulated by using various configurations of passive devices such as vortex generators, air barriers, and slot in the test section floor which was extended into the contraction cone. Mean velocity and velocity fluctuations have been measured using a hot-wire anemometry system. Mean velocity, turbulence intensity, turbulence scale, and power spectral density of velocity fluctuations have been obtained from the experiments for various configuration of the passive devices. It is shown that the integral length scale factor can be controlled using various combinations of the passive devices. © 2011 Springer-Verlag.
Varshney K.,Taitem Engineering |
Chang S.,Cornell University |
Wang Z.J.,Cornell University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2013
Falling parallelograms exhibit coupled motion of autogyration and tumbling, similar to the motion of falling tulip seeds, unlike maple seeds which autogyrate but do not tumble, or rectangular cards which tumble but do not gyrate. This coupled tumbling and autogyrating motion are robust, when card parameters, such as aspect ratio, internal angle, and mass density, are varied. We measure the three-dimensional (3D) falling kinematics of the parallelograms and quantify their descending speed, azimuthal rotation, tumbling rotation, and cone angle in each falling. The cone angle is insensitive to the variation of the card parameters, and the card tumbling axis does not overlap with but is close to the diagonal axis. In addition to this connection to the dynamics of falling seeds, these trajectories provide an ideal set of data to analyze 3D aerodynamic force and torque at an intermediate range of Reynolds numbers, and the results will be useful for constructing 3D aerodynamic force and torque models. Tracking these free falling trajectories gives us a nonintrusive method for deducing instantaneous aerodynamic forces. We determine the 3D aerodynamic forces and torques based on Newton-Euler equations. The dynamical analysis reveals that, although the angle of attack changes dramatically during tumbling, the aerodynamic forces have a weak dependence on the angle of attack. The aerodynamic lift is dominated by the coupling of translational and rotational velocities. The aerodynamic torque has an unexpectedly large component perpendicular to the card. The analysis of the Euler equation suggests that this large torque is related to the deviation of the tumbling axis from the principle axis of the card. © 2013 American Physical Society.
Shapiro I.,Taitem Engineering
ASHRAE Journal | Year: 2010
A report of high energy savings at a multifamily building in Ithaca, New York, US, resulting from the replacement of an old steam boiler with a new hot water boiler, led to a survey of similar completed projects in the city to assess their high energy saving potential. An evaluation of water use in steam-heated buildings was conducted and fifty buildings were surveyed for which water use records were available. Water use in steam-heated buildings was found to be 79% higher than in buildings not heated with steam, demonstrating more than the national average for residential water consumption per person. Preretrofit and post-retrofit utility bills were analyzed for seven multifamily residential buildings where old steam boilers were replaced and for which utility bills were available. Six of the seven buildings had participated in a program of the New York State Energy Research and Development Authority (NYSERDA).